| 1. |
- Winberg, Svante, et al.
(författare)
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Effect of social rank on brain monoaminergic activity in a cichlid fish
- 1997
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Ingår i: BRAIN BEHAVIOR AND EVOLUTION. - : KARGER. - 0006-8977. ; 49:4, s. 230-236
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Tidskriftsartikel (refereegranskat)abstract
- In Haplochromis burtoni, an African cichlid fish, male sexual maturation is regulated via social interactions, and these effects are mediated by gonadotropin-releasing-hormone (GnRH)-containing neurons in the preoptic area of the brain. Since brain monoam
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| 2. |
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| 3. |
- Abbey-Lee, Robin N., et al.
(författare)
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The Influence of Rearing on Behavior, Brain Monoamines, and Gene Expression in Three-Spined Sticklebacks
- 2018
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Ingår i: Brain, behavior, and evolution. - Basel : S. Karger AG. - 0006-8977 .- 1421-9743. ; 91:4, s. 201-213
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Tidskriftsartikel (refereegranskat)abstract
- The causes of individual variation in behavior are often not well understood, and potential underlying mechanisms include both intrinsic and extrinsic factors, such as early environmental, physiological, and genetic differences. In an exploratory laboratory study, we raised three-spined sticklebacks (Gasterosteus aculeatus) under 4 different environmental conditions (simulated predator environment, complex environment, variable social environment, and control). We investigated how these manipulations related to behavior, brain physiology, and gene expression later in life, with focus on brain dopamine and serotonin levels, turnover rates, and gene expression. The different rearing environments influenced behavior and gene expression, but did not alter monoamine levels or metabolites. Specifically, compared to control fish, fish exposed to a simulated predator environment tended to be less aggressive, more exploratory, and more neophobic; and fish raised in both complex and variable social environments tended to be less neophobic. Exposure to a simulated predator environment tended to lower expression of dopamine receptor DRD4A, a complex environment increased expression of dopamine receptor DRD1B, while a variable social environment tended to increase serotonin receptor 5-HTR2B and serotonin transporter SLC6A4A expression. Despite both behavior and gene expression varying with early environment, there was no evidence that gene expression mediated the relationship between early environment and behavior. Our results confirm that environmental conditions early in life can affect phenotypic variation. However, the mechanistic pathway of the monoaminergic systems translating early environmental variation into observed behavioral responses was not detected.
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| 4. |
- Abreu, Murilo S., et al.
(författare)
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Monoaminergic levels at the forebrain and diencephalon signal for the occurrence of mutualistic and conspecific engagement in client reef fish
- 2018
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Ingår i: Scientific Reports. - : NATURE PUBLISHING GROUP. - 2045-2322. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Social interactions are commonly found among fish as in mammals and birds. While most animals interact socially with conspecifics some however are also frequently and repeatedly observed to interact with other species (i.e. mutualistic interactions). This is the case of the (so-called) fish clients that seek to be cleaned by other fish (the cleaners). Clients face an interesting challenge: they raise enough motivation to suspend their daily activities as to selectively visit and engage in interactions with cleaners. Here we aimed, for the first time, to investigate the region-specific brain monoaminergic level differences arising from individual client fish when facing a cleaner (interspecific context) compared to those introduced to another conspecific (socio-conspecific context). We show that monoaminergic activity differences occurring at two main brain regions, the diencephalon and the forebrain, are associated with fish clients' social and mutualistic activities. Our results are the first demonstration that monoaminergic mechanisms underlie client fish mutualistic engagement with cleanerfish. These pathways should function as a pre-requisite for cleaning to occur, providing to clients the cognitive and physiological tools to seek to be cleaned.
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| 5. |
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| 6. |
- Amcoff, Mirjam, et al.
(författare)
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Male Courtship Pheromones Affect Female Behaviour in the Swordtail Characin ( Corynopoma riisei)
- 2014
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Ingår i: Ethology. - : Wiley. - 0179-1613 .- 1439-0310. ; 120:5, s. 463-470
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Tidskriftsartikel (refereegranskat)abstract
- Pheromones constitute an important cue used by both males and females during courtship. Here, we investigate the effect of male pheromones on female behaviour in the swordtail characin (Corynopoma riisei), a species of fish where males have a caudal pheromone gland which has been suggested to affect female behaviour during courtship. We subjected female C.riisei to male courtship pheromones and investigated the effect on both female behaviour and brain serotonergic activity levels compared to a control group. While no difference in serotonergic activity was found, the pheromone-treated females showed lower stress levels compared to the control group. Furthermore, pheromone-treated females increased locomotor activity over time, while a decrease in locomotor activity was observed in the control group. These results suggest that the male courtship pheromones may serve to reduce female stress and increase female activity, possibly to aid males in gaining access to females and facilitating sperm transfer.
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| 7. |
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| 8. |
- Axling, Johanna, 1986-, et al.
(författare)
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Boldness, activity, and aggression : Insights from a large-scale study in Baltic salmon (Salmo salar L)
- 2023
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 18:7
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Tidskriftsartikel (refereegranskat)abstract
- Atlantic salmon (Salmo salar) display high levels of agonistic behavior in aquaculture farms, resulting in fin damage and chronic stress. Aggression affects fish growth and performance negatively and presents a serious welfare problem. Indeed, it would be beneficial to identify, separate or exclude overly aggressive individuals. Research on behavioral syndromes suggests that aggressive behavior may correlate with traits from other contexts, such as boldness and locomotory activity. We aimed to develop a high-throughput method to quantify and predict aggressive behavior of individual parr in hatchery-reared Baltic salmon (Salmo salar L.). We screened approximately 2000 parr in open field (OF) and mirror image stimulation (MIS) tests. We extracted seven variables from video tracking software for each minute of the tests; distance moved and duration moving (activity), the duration in and number of entries to the center of the arena (boldness), the distance moved in, and duration spent in the area adjacent to the mirror during the MIS test (aggressiveness) and head direction (lateralization). To investigate the relationship between activity, boldness, and aggression we first correlated the first six variables to one another. Second, we assigned individuals to high, medium, low or zero aggression groups based on the MIS test and quantified activity and boldness in each group. Third, we analyzed whether the fish viewed the mirror with the left or right eye. Our results show that medium and low aggressive fish were the most active, while highly aggressive fish showed average activity. Aggressive groups did not differ in boldness. Activity and boldness were positively correlated. Finally, we detected a preference for fish to view the mirror with the left eye. We conclude that although the OF may not accurately predict aggressive behavior, the MIS test can be used for large-scale aggression profiling of juvenile salmon
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| 9. |
- Axling, Johanna, et al.
(författare)
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Boldness in Zebrafish Larvae-Development and Differences between a Domesticated Lab Strain and Offspring of Wild-Caught Fish
- 2022
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Ingår i: Fishes. - : MDPI AG. - 2410-3888. ; 7:4
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Tidskriftsartikel (refereegranskat)abstract
- Zebrafish (Danio rerio) are becoming one of the most important model organisms in behavioural neuroscience. It has been shown repeatedly that different zebrafish strains show large behavioural differences. These divergent behavioural profiles may have a genetic basis, but environmental factors and previous experience are also known to greatly affect the behavioural phenotype of zebrafish. It could be expected that behavioural differences at the larval stage should be less affected by environmental factors and experience. In the present study, we screened larvae of zebrafish of the AB strain and offspring of wild-caught zebrafish for boldness, using an open field test. In order to follow the behavioural development, we studied larvae at the age of 5-, 7-, 12- and 30-days post fertilization (dpf). Behaviour, as well as behavioural development, clearly differed between the larvae of the different strains. Wild larvae showed larger total distance moved than AB larvae, both at light and dark conditions. These differences were already present at 12 dpf but became more pronounced with age. Wild larvae had a greater variance compared to AB larvae for most of the variables. We have previously shown that bold and shy adult zebrafish differ in the brain expression of dopamine and opioid receptors. The results of the current study show that wild larvae display significantly higher brain expression of drd2b than AB larvae at 30 dpf, a difference that could be related to differences in activity. We did not detect any differences in the expression of opioid receptors.
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| 10. |
- Axling, Johanna
(författare)
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Intraspecific divergence and phenotypic plasticity in behavioural profiles of teleost fish
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Behavioural differences between and within individuals can greatly affect the outcome of behavioural studies. In addition, behavioural interactions between individuals can compromise the health and welfare of captive fish. In paper I, I investigate the relationship between locomotory activity, boldness and aggressive behaviour in ~2000 hatchery-reared Baltic salmon parr (Salmo salar L), with the aim to predict aggression level from activity and boldness displayed in the open field test. We found that activity and boldness were positively correlated while they were not correlated with aggression level measured in the mirror stimulation test. Surprisingly, medium and low aggressive fish were the most active, while highly aggressive fish showed only average activity. We conclude that the open field test, although efficient, does not accurately predict aggressive behaviour. However, the mirror stimulation test can be used for high-throughput aggression profiling of juvenile salmon. In paper II, I tested a subset of the salmon parr for a second time, to quantify behavioural consistency between trials and to investigate if phenotypic plasticity was related to aggression level. Our results show that activity was the most stable behavioural variable between trials. Even though aggression was not consistent between tests, we found that the fish displaying a low level of aggression in the first test were less consistent in their behaviour than highly aggressive fish. In paper III, we compared the behavioural development of zebrafish larvae of two strains, the AB strain and 5th generation offspring of wild-caught zebrafish from India. Individual larvae were screened for activity and boldness at the age of 5-, 7-, 12- and 30-days post fertilization using an open field test with alternating light and dark cycles. Furthermore, we analysed mRNA expression of genes encoding serotonin, dopamine, galanin and opioid receptor subunits, as well the peptide neurotransmitter spexin in whole brain samples from juveniles, with the aim to investigate potential neuroendocrine mechanisms of divergent behavioural profiles. Our results show that larvae from the wild strain had higher activity and greater variance in their behaviour than AB larvae, under both light and dark conditions. Wild larvae also had significantly higher expression of dopamine receptor subunit drd2b at 30 days post fertilization, a difference that could be related to difference in activity. In conclusion, the results presented in this thesis contribute to our understanding of animal behavioural profiles, at both an intraspecific and intraindividual level.
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| 11. |
- Axling, Johanna, et al.
(författare)
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Locomotory activity is more consistent over trials than thigmotaxis and aggressive behaviour in sea-ranched Baltic salmon (Salmo salar L.)
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- In the current study we examined the behavioural consistency over time of activity, boldness and aggressive behaviour in Baltic salmon (Salmo salar L) parr. We performed a combined open field and mirror stimulation test on two test occasions, recording three behavioural variables: duration moving in the whole arena (activity), duration in centre zone (boldness) and distance between nose and mirror (aggression) during the mirror stimulation test. Of these behavioural variables activity proved the most consistent between trials. Moreover, the fish that displayed least aggressive behaviour in the first trial had the largest variance in their behavioural variables compared to highly aggressive fish, which showed more consistent levels of the behavioural variables. Overall, aggression level in the first test was a strong predictor of the other behavioural variables, in addition to significant effects of water temperature and body weight. In conclusion, our results show that juvenile Baltic salmon classified according to aggression level during the first test also differ in other aspects of their behavioural profile, and highly aggressive salmon are less phenotypically plastic compared to low aggressive fish.
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| 12. |
- Backstroem, Tobias, et al.
(författare)
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Social effects on AVT and CRF systems
- 2021
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Ingår i: Fish Physiology & Biochemistry. - : Springer Nature. - 0920-1742 .- 1573-5168. ; 47:6, s. 1699-1709
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Tidskriftsartikel (refereegranskat)abstract
- Stress and aggression have negative effects on fish welfare and productivity in aquaculture. Thus, research to understand aggression and stress in farmed fish is required. The neuropeptides arginine-vasotocin (AVT) and corticotropin-releasing factor (CRF) are involved in the control of stress and aggression. Therefore, we investigated the effect of agonistic interactions on the gene expression of AVT, CRF and their receptors in juvenile rainbow trout (Oncorhynchus mykiss). The social interactions lead to a clear dominant-subordinate relationship with dominant fish feeding more and being more aggressive. Subordinate fish had an upregulation of the AVT receptor (AVT-R), an upregulation of CRF mRNA levels, and higher plasma cortisol levels. The attenuating effect of AVT on aggression in rainbow trout is proposed to be mediated by AVT-R, and the attenuating effect of the CRF system is proposed to be mediated by CRF.
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| 13. |
- Backstrom, Tobias, et al.
(författare)
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Serotonin Coordinates Responses to Social Stress : What We Can Learn from Fish
- 2017
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Ingår i: Frontiers in Neuroscience. - : Frontiers Media SA. - 1662-4548 .- 1662-453X. ; 11
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Forskningsöversikt (refereegranskat)abstract
- Social interaction is stressful and subordinate individuals are often subjected to chronic stress, which greatly affects both their behavior and physiology. In teleost fish the social position of an individual may have long-term effects, such as effects on migration, age of sexual maturation or even sex. The brain serotonergic system plays a key role in coordinating autonomic, behavioral and neuroendocrine stress responses. Social subordination results in a chronic activation of the brain serotonergic system an effect, which seems to be central in the subordinate phenotype. However, behavioral effects of short-term acute activation of the serotonergic system are less obvious. As in other vertebrates, divergent stress coping styles, often referred to as proactive and reactive, has been described in teleosts. As demonstrated by selective breeding, stress coping styles appear to be partly heritable. However, teleost fish are characterized by plasticity, stress coping style being affected by social experience. Again, the brain serotonergic system appears to play an important role. Studies comparing brain gene expression of fish of different social rank and/or displaying divergent stress coping styles have identified several novel factors that seem important for controlling aggressive behavior and stress coping, e.g., histamine and hypocretin/orexin. These may also interact with brain monoaminergic systems, including serotonin.
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| 14. |
- Backström, Tobias, et al.
(författare)
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Anaesthesia and handling stress effects on pigmentation and monoamines in Arctic charr
- 2017
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Ingår i: Environmental Biology of Fishes. - : Springer. - 0378-1909 .- 1573-5133. ; 100:5, s. 471-480
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Tidskriftsartikel (refereegranskat)abstract
- Stress responsiveness differs between individuals and is often categorized into different stress coping styles. Using these stress coping styles for selection in fish farming could be beneficial, since stress is one main factor affecting welfare. In Arctic charr (Salvelinus alpinus) carotenoid pigmentation is associated with stress responsiveness and stress coping styles. Thus this could be an important tool to use for selection of stress resilient charr. However, anaesthetics seem to affect carotenoid pigmentation, and it would be better if the method for selection could be implemented during normal maintenance, which usually includes anaesthetics. Therefore, this study investigated how the use of anaesthetics affected carotenoid pigmentation, i.e. number of spots, over time compared to no-anaesthetic treatment. Additionally, the stress indicators monoamines and glucocorticoids were investigated. The results indicate that the anaesthetic MS-222 affects number of spots on the right side. This anaesthetic also increased dopaminergic activity in the telencephalon. Both brain dopaminergic and serotonergic activity was associated with spottiness. Further, behaviour during anaesthetization was associated with spots on the left side, but not the right side. Repetition of the same treatment seemed to affect spot numbers on the right side. In conclusion, this study shows that inducing stress in charr affects the carotenoid spots. Thus, it is possible to use anaesthetics when evaluating spottiness although careful planning is needed.
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| 15. |
- Backström, Tobias, et al.
(författare)
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Arginine-vasotocin influence on aggressive behaviour and dominance in rainbow trout
- 2009
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Ingår i: Physiology and Behavior. - : Elsevier BV. - 0031-9384 .- 1873-507X. ; 96:3, s. 470-475
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Tidskriftsartikel (refereegranskat)abstract
- The mammalian neuropeptide arginine-vasopressin (AVP) and its non-mammalian homologue arginine-vasotocin (AVT) are involved in social behavior including aggression in vertebrates. Juvenile rainbow trout (Onchorhynchus mykiss) are highly territorial and we tested the effect of two different doses each of AVT and Manning compound, an AVP V1A receptor antagonist, on aggressive behavior and the outcome of staged fights for social dominance in size matched pairs. Each pair consisted of one fish receiving AVT or Manning compound through an intracerebroventricular (icv) injection and one fish receiving a similar icv injection of saline. In addition, plasma cortisol and brain serotonergic activity were monitored. Fish receiving AVT at a dose of 200 ng became subordinate whereas AVT at a dose of 20 ng had no effect on the outcome of fights for social dominance. Further, Manning compound had no effect on the outcome of fights for dominance but at a dose of 200 ng it had an effect on fight duration. Fish receiving 200 ng Manning compound and losing dyadic fights appeared to take longer to become subordinate. Neither AVT nor Manning compound had any effects on plasma cortisol levels or brainstem serotonergic activity. The apparent inhibiting effect of AVT on aggression could be centrally mediated.
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| 16. |
- Backström, Tobias, et al.
(författare)
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Central corticotropin releasing factor and social stress
- 2013
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Ingår i: Frontiers in Neuroscience. - : Frontiers Media SA. - 1662-4548 .- 1662-453X. ; 7
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Forskningsöversikt (refereegranskat)abstract
- Social interactions are a main source of stress in vertebrates. Social stressors, as well as other stressors, activate the hypothalamic-pituitary-adrenal (HPA) axis resulting in glucocorticoid release. One of the main components of the HPA axis is corticotropin releasing factor (CRF). The neuropeptide CRF is part of a peptide family including CRF, urocortin 1-3, urotensin 1-3, and sauvagine. The actions of the CRF family are mediated by at least two different receptors with different anatomical distribution and affinities for the peptides. The CRF peptides affect several behavioral and physiological responses to stress including aggression, feeding, and locomotor activity. This review will summarize recent research in vertebrates concerning how social stress interacts with components of the CRF system. Consideration will be taken to the different models used for social stress ranging from social isolation, dyadic interactions, to group dominance hierarchies. Further, the temporal effect of social stressor from acute, intermittent, to chronic will be considered. Finally, strains selected for specific behavior or physiology linked to social stress will also be discussed.
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| 17. |
- Backström, Tobias, et al.
(författare)
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CRF and urotensin I effects on aggression and anxiety-like behavior in rainbow trout
- 2011
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Ingår i: Journal of Experimental Biology. - : The Company of Biologists. - 0022-0949 .- 1477-9145. ; 214:6, s. 907-914
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Tidskriftsartikel (refereegranskat)abstract
- Corticotropin-releasing factor (CRF) is central in the stress response but also modulates several behaviors including anxiety-related behaviors and aggression. In this study, juvenile rainbow trout (Oncorhynchus mykiss) were tested for competitive ability, determined during dyadic fights for dominance, after intracerebroventricular (i.c.v.) administration of CRF, urotensin I (UI), the non-specific CRF antagonist alpha-helical RF9-41 (ahCRF) or the CRF receptor subtype 1-specific antagonist antalarmin, when paired with a mass-matched con-specific injected with saline. In addition, isolated fish received the same substances. Plasma cortisol and brain monoamines were monitored in all fish. Most fish receiving CRF showed a conspicuous behavior consisting of flaring the opercula, opening the mouth and violent shaking of the head from side to side. When this occurred, the fish immediately forfeited the fight. Similar behavior was observed in most fish receiving UI but no effect on outcome of dyadic fights was noted. This behavior seems similar to non-ambulatory motor activity seen in rats and could be anxiety related. Furthermore, fish receiving CRF at a dose of 1000. ng became subordinate, whereas all other treatments had no effects on the outcome of dyadic fights. In addition, isolated fish receiving ahCRF had lower brain stem concentrations of 5-hydroxyindoleacetic acid, serotonin, 3,4-dihydroxyphenylacetic acid and dopamine. In conclusion, CRF seems to attenuate competitive ability, and both CRF and UI seem to induce anxiety-like behavior.
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| 18. |
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| 19. |
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| 20. |
- Backström, Tobias, 1976-
(författare)
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Roles of Arginine-Vasotocin and Corticotropin-Releasing Hormone in Stress Responses and Agonistic Behaviour of Rainbow Trout
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The neuropeptides arginine-vasotocin (AVT) and corticotropin-releasing hormone (CRH) are involved in the hypothalamic-pituitary-interrenal (HPI) axis. During stress, the HPI axis is activated and cortisol is released into the blood. In addition to their role in the HPI axis, AVT and CRH also have behavioural effects. The roles of AVT and CRH in stress responses and agonistic behaviour were studied in this thesis, using two different models. In the first model, two strains of rainbow trout (Onchorhynchus mykiss) divergent in stress-induced release of cortisol were investigated. This was done by observing behaviour and stress responses under different conditions. These strains were found to have divergent stress coping strategies based on the observed behaviour and levels of plasma cortisol. This divergence in behaviour could be associated with the CRH system, since the mRNA levels of CRH differed between the strains during stress. However, no differences between strains were observed in AVT or its receptor expressions. In the second model, non-selected rainbow trout were paired and the effect of intracerebroventricular (icv) injections of an active substance (AVT, CRH or the CRH related peptide Urotensin-I (UI)) on fights for dominance was investigated. One fish of the pair received the active substance icv and the other received saline icv. Fish receiving AVT became subordinate in accordance with the suggestion that AVT attenuates aggression in territorial vertebrates. Fish receiving CRH became subordinate whereas UI showed no effect on fights for dominance. Further, both CRH and UI induced an anxiety-related behaviour similar to non-ambulatory motor activity in rats. In addition, CRH appeared to affect the dopaminergic and serotonergic systems. In this thesis, it is suggested that CRH is involved in the behavioural modulation of the stress coping strategies in teleost fish. Further, AVT and CRH seem to act inhibitory on aggressive behaviour.
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| 21. |
- Backström, Tobias, et al.
(författare)
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Social stress effects on pigmentation and monoamines in Arctic charr
- 2015
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Ingår i: Behavioural Brain Research. - : Elsevier BV. - 0166-4328 .- 1872-7549. ; 291, s. 103-107
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Tidskriftsartikel (refereegranskat)abstract
- Pigmentation often signals status and in general melanin-based pigmentation is indicative of aggression and stress resilience in vertebrates. This is evident in the salmonids Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss) where more melanin spotted individuals are more stress resilient. However, in the salmonid Arctic charr (Salvelinus alpinus) it seems as if it is carotenoid-based pigmentation that signals aggression and stress resilience. In our study, social stress effects on carotenoid-based spots, and behavioural and physiological stress responses were investigated. Socially stressed individuals have more spots, and behavioural stress responses were associated with spots. Some of the results concerning physiological stress responses, such as plasma cortisol levels and monoaminergic activity, are associated with spottiness. Further, the earlier proposed lateralization of spots, with left side connected to stress responsiveness and right side to aggression, is to some extent validated although not conclusively. In conclusion, this study provides further evidence that more stressed charr have more carotenoid spots, and for the first time monoaminergic activity is shown to be connected with carotenoid pigmentation.
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| 22. |
- Backström, Tobias, et al.
(författare)
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Stress effects on AVT and CRF systems in two strains of rainbow trout (Oncorhynchus mykiss) divergent in stress responsiveness
- 2011
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Ingår i: Hormones and Behavior. - : Elsevier BV. - 0018-506X .- 1095-6867. ; 59:1, s. 180-186
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Tidskriftsartikel (refereegranskat)abstract
- The aim for this study was to examine whether the F4 generation of two strains of rainbow trout divergent in their plasma cortisol response to confinement stress (HR: high responder or LR: low responder) would also differ in stress-induced effects on forebrain concentrations of mRNA for corticotropin-releasing factor (CRF). arginine vasotocin (AVT). CRF receptor type 1 (CRF-R1). CRF receptor type 2 (CRF-R2) and AVT receptor (AVT-R). In addition, plasma cortisol concentrations, brainstem levels of monoamines and monoamine metabolites, and behaviour during confinement were monitored. The results confirm that HR and LR trout differ in their cortisol response to confinement and show that fish of these strains also differ in their behavioural response to confinement. The HR trout displayed significantly higher locomotor activity while in confinement than LR trout. Moreover, following 180 min of confinement HR fish showed significantly higher forebrain concentrations of CRF mRNA than LR fish. Also, when subjected to 30 min of confinement HR fish showed significantly lower CRF-R2 mRNA concentrations than LR fish, whereas there were no differences in CRF-R1. AVT or AVT-R mRNA expression between LR and HR fish either at 30 or 180 min of confinement. Differences in the expression of CRF and CRF-R2 mRNA may be related to the divergence in stress coping displayed by these rainbow trout strains.
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| 23. |
- Basic, Dean, et al.
(författare)
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Changes in regional brain monoaminergic activity and temporary down-regulation in stress response from dietary supplementation with L-tryptophan in Atlantic cod (Gadus morhua)
- 2013
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Ingår i: British Journal of Nutrition. - 0007-1145 .- 1475-2662. ; 109:12, s. 2166-2174
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Tidskriftsartikel (refereegranskat)abstract
- The brain monoamines serotonin (5-hydroxytryptamine; 5-HT) and dopamine (DA) both play an integrative role in behavioural and neuroendocrine responses to challenges, and comparative models suggest common mechanisms for dietary modulation of transmission by these signal substances in vertebrates. Previous studies in teleosts demonstrate that 7 d of dietary administration with L-tryptophan (Trp), the direct precursor of 5-HT, suppresses the endocrine stress response. The present study investigated how long the suppressive effects of a Trp-enriched feed regimen, at doses corresponding to two, three or four times the Trp levels in commercial feed, last in juvenile Atlantic cod (Gadus morhua) when the fish are reintroduced to a diet with standard amino acid composition. We also wanted to determine whether Trp supplementation induced changes in brain monoaminergic neurochemistry in those forebrain structures innervated by DA- and 5-HTergic neurons, by measuring regional activity of DA and 5-HT in the lateral pallial regions (Dl) of the telencephalon and nucleus lateralis tuberis (NLT) of the hypothalamus. Dietary Trp resulted in a dose-dependent suppression in plasma cortisol among fish exposed to confinement stress on the first day following experimental diet; however, such an effect was not observed at 2 or 6 d after Trp treatment. Feeding the fish with moderate Trp doses also evoked a general increase in DA and 5-HT-ergic activity, suggesting that these neural circuits within the NLT and Dl may be indirectly involved in regulating the acute stress response.
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| 24. |
- Basic, D., et al.
(författare)
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Context-dependent responses to novelty in Rainbow trout (Oncorhynchus mykiss), selected for high and low post-stress cortisol responsiveness
- 2012
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Ingår i: Physiology and Behavior. - : Elsevier BV. - 0031-9384 .- 1873-507X. ; 105:5, s. 1175-1181
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Tidskriftsartikel (refereegranskat)abstract
- Previous studies in a rainbow trout model, selectively bred for high (HR) and low (LR) post stress plasma cortisol levels, have yielded data that are indicative of contrasting stress coping styles. Fish from the HR line have been suggested to display a more diverse behavioral repertoire in challenging situations than the LR counterpart. The present study addressed whether such variation in behavioral flexibility traits was evident in different experimental settings using these selection lines. The fish were subjected to three sets of challenges (novel object test, resident-intruder test and confinement stressor test), all which were repeated a week later. Introducing a novel object evoked a divergent behavioral response in association with feeding: fish from the LR line displayed consistently suppressed feed intake while the HR fish remained unaffected. This observation was found to be repeatable along with attack latency and movement activity from the resident-intruder and confinement stressor tests. These results indicate that the behavioral responses in this animal model are context-dependent and shed new light on the expression of behavioral flexibility.
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| 25. |
- Basic, Dean, et al.
(författare)
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Short- and long-term effects of dietary L-tryptophan supplementation on the neuroendocrine stress response in seawater-reared Atlantic salmon (Salmo salar)
- 2013
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Ingår i: Aquaculture. - : Elsevier BV. - 0044-8486 .- 1873-5622. ; 388, s. 8-13
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Tidskriftsartikel (refereegranskat)abstract
- The essential amino acid L-tryptophan (Trp) is the immediate precursor of the neurotransmitter serotonin (5-HT). Supplementing Trp through diet has been shown to suppress the neuroendocrine stress response in vertebrates including teleosts. In salmonid fish, adjusting to the social environment as well as habituation to seawater involves the neuroendocrine stress response, suggesting that such environmental factors may modulate the stress-reducing effects of Trp. To date, studies that have investigated the neuroendocrine effects of dietary Trp have only been conducted in rainbow trout (Oncorhynchus mykiss), a salmonid species, under conditions featuring social isolation in the freshwater environment. Here, we address the effects of dietary Trp on post-stress plasma cortisol and hypothalamic monoamines in seawater-adapted Atlantic salmon (Salmo salar), reared at densities relevant for aquaculture. Fish were given feed containing 1, 2, 3 or 4 times the Trp content in normal feed for one week. Subsequently, the fish were reintroduced to feed containing the lowest Trp level, corresponding to standard commercial feed for a number of days prior to exposure to an acute confinement stressor. Basal plasma cortisol levels were lower among non-stressed fish at 1 and 10 days post dietary Trp supplementation. By comparison, stressed fish displayed stimulatory post-stress plasma cortisol responses at 1 and 2 days after the Trp regimen was terminated. However, a reversed pattern was observed among these fish at 10 days after Trp treatment. The overall effects of dietary Trp were more pronounced in dopamine (DA) neurochemistry compared to 5-HT in the hypothalamus. The results demonstrate both short-and long-term effects of elevated dietary Trp on the neuroendocrine stress response. These findings suggest that hypothalamic DA may be more involved than 5-HT in the stress reducing effects of Trp in seawater-adapted Atlantic salmon, reared at densities relevant for aquaculture.
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| 26. |
- Behere, Anish, 1993-, et al.
(författare)
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Visualization of early oligomeric α‐synuclein pathology and its impact on the dopaminergic system in the (Thy‐1)‐h[A30P]α‐syn transgenic mouse model
- 2021
-
Ingår i: Journal of Neuroscience Research. - : John Wiley & Sons. - 0360-4012 .- 1097-4547. ; 99:10, s. 2525-2539
-
Tidskriftsartikel (refereegranskat)abstract
- Aggregation of alpha-synuclein (alpha-syn) into Lewy bodies and Lewy neurites is a pathological hallmark in the Parkinson ' s disease (PD) brain. The formation of alpha-syn oligomers is believed to be an early pathogenic event and the A30P mutation in the gene encoding alpha-syn, causing familial PD, has been shown to cause an accelerated oligomerization. Due to the problem of preserving antigen conformation on tissue surfaces, alpha-syn oligomers are difficult to detect ex vivo using conventional immunohistochemistry with oligomer-selective antibodies. Herein, we have instead employed the previously reported alpha-syn oligomer proximity ligation assay (ASO-PLA), along with a wide variety of biochemical assays, to discern the pathological progression of alpha-syn oligomers and their impact on the dopaminergic system in male and female (Thy-1)-h[A30P]alpha-syn transgenic (A30P-tg) mice. Our results reveal a previously undetected abundance of alpha-syn oligomers in midbrain of young mice, whereas phosphorylated (pS129) and proteinase k-resistant alpha-syn species were observed to a larger extent in aged mice. Although we did not detect loss of dopaminergic neurons in A30P-tg mice, a dysregulation in the monoaminergic system was recorded in older mice. Taken together, ASO-PLA should be a useful method for the detection of early changes in alpha-syn aggregation on brain tissue, from experimental mouse models in addition to post mortem PD cases.
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| 27. |
- Bell, Alison M., et al.
(författare)
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Variable neuroendocrine responses to ecologically-relevant challenges in sticklebacks
- 2007
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Ingår i: Physiology and Behavior. - : Elsevier BV. - 0031-9384 .- 1873-507X. ; 91:1, s. 15-25
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Tidskriftsartikel (refereegranskat)abstract
- Variable neuroendocrine responses to ecologically-relevant challenges in sticklebacks. PHYSIOL BEHAV 00(0) 000-000, 2006. Here, we compare the behavioral, endocrine and neuroendocrine responses of individual sticklebacks exposed to either an unfamiliar conspecific or to a predator. We found that the two stressors elicited a similar hypothalamic–pituitary–interrenal response as assessed by whole-body concentrations of cortisol, but produced quite different patterns of change in brain monoamine and monoamine metabolite content as assessed by concentrations of serotonin (5-HT), dopamine (DA), norepinephrine (NE) and the monoamine metabolites 5-hydroxyindole acetic acid (5-HIAA), homovanillic acid (HVA) and 3-4-dihydroxyphenylacetic acid (DOPAC). For example, relative to baseline levels, NE levels were elevated in individuals exposed to a predator but were lower in individuals confronted by a challenging conspecific. Levels of monoamine neurotransmitters in specific regions of the brain showed extremely close links with behavioral characteristics. Frequency of attacking a conspecific and inspecting a predator were both positively correlated with concentrations of NE. However, whereas serotonin was negatively correlated with frequency of attacking a conspecific, it was positively associated with predator inspection. The data indicate that the qualitative and quantitative nature of the neuroendocrine stress response of sticklebacks varies according to the nature of the stressor, and that interindividual variation in behavioural responses to challenge are reflected by neuroendocrine differences.
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| 28. |
- Berg, Cecilia, et al.
(författare)
-
Developmental exposure to fluoxetine modulates the serotonin system in hypothalamus
- 2013
-
Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:1
-
Tidskriftsartikel (refereegranskat)abstract
- The selective serotonin reuptake inhibitor (SSRI) fluoxetine (FLU, Prozac®) is commonly prescribed for depression in pregnant women. This results in SSRI exposure of the developing fetus. However, there are knowledge gaps regarding the impact of SSRI exposure during development. Given the role of serotonin in brain development and its cross-talk with sex hormone function, we investigated effects of developmental exposure to pharmacologically relevant concentrations of FLU (3 and 30 nM (measured)) on brain neurotransmitter levels, gonadal differentiation, aromatase activity in brain and gonads, and the thyroid system, using the Xenopus tropicalis model. Tadpoles were chronically exposed (8 weeks) until metamorphosis. At metamorphosis brains were cryosectioned and levels of serotonin, dopamine, norepinephrine, and their metabolites 5-hydroxyindoleacetic acid, 3,4-dihydroxyphenylacetic acid, and homovanillic acid were measured in discrete regions (telencephalon, hypothalamus and the reticular formation) of the cryosections using high-performance liquid chromatography. Exposure to 30 nM FLU increased the concentration of 5-hydroxyindoleacetic acid in hypothalamus compared with controls. FLU exposure did not affect survival, time to metamorphosis, thyroid histology, gonadal sex differentiation, or aromatase activity implying that the effect on the serotonergic neurotransmitter system in the hypothalamus region was specific. The FLU concentration that impacted the serotonin system is lower than the concentration measured in umbilical cord serum, suggesting that the serotonin system of the developing brain is highly sensitive to in utero exposure to FLU. To our knowledge this is the first study showing effects of developmental FLU exposure on brain neurochemistry. Given that SSRIs are present in the aquatic environment the current results warrant further investigation into the neurobehavioral effects of SSRIs in aquatic wildlife.
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| 29. |
- Bikovski, Lior, et al.
(författare)
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Lessons, insights and newly developed tools emerging from behavioral phenotyping core facilities
- 2020
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Ingår i: Journal of Neuroscience Methods. - : Elsevier BV. - 0165-0270 .- 1872-678X. ; 334
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Forskningsöversikt (refereegranskat)abstract
- Scientific investigations, in general, and research in neuroscience, in particular, are becoming ever more complex and require the integration of different techniques. Behavioral assays, which are among the most frequently used methodologies in neuroscience, nowadays rely on advanced, sophisticated technologies that require proficient application. Therefore, behavioral core facilities are becoming essential support units, as they provide the specialized expert research services needed to conduct advanced neuroscience. We here review the lessons learned and insights gathered from managing behavioral core facilities in different academic research institutes. This review addresses several issues, including: the advantages of behavioral core facilities, considerations for establishing a behavioral core facility, and the methodological advances made through calibration and standardization of assay protocols and the development of new assays. Collectively, the review highlights the benefits of both working within and collaborating with behavioral core facility units and emphasizes the potential progress in neuro-phenotyping that such facilities provide.
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| 30. |
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| 31. |
- Brelin, Daniel, et al.
(författare)
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Divergent stress coping styles in juvenile brown trout (Salmo trutta)
- 2005
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Ingår i: ANNALS OF THE NEW YORK ACADEMY OF SCIENCES: TRENDS IN COMPARATIVE ENDOCRINOLOGY AND NEUROBIOLOGY. ; 1040, s. 239-245
-
Tidskriftsartikel (refereegranskat)abstract
- Two distinct stress coping styles, proactive and reactive, have been stated in various animal studies. This divergence in coping has also been indicated in salmonid fish. Here, we test the hypothesis that divergent stress coping styles are identifiable in a sea-ranched brown trout population. To that end, we used a series of tests on individual juvenile brown trout, with each test including a common key aspect of the two different coping styles. Using a clustering method (SAS: PROC FASTCLUS), two groups that clearly differed both in blood chemistry (noradrenalin and adrenalin levels) following confinement and in behavior during hypoxia were identified.
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| 32. |
- Brelin, Daniel, et al.
(författare)
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Frequency distribution of coping strategies in four populations of brown trout (Salmo trutta)
- 2008
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Ingår i: Hormones and Behavior. - : Elsevier BV. - 0018-506X .- 1095-6867. ; 53:4, s. 546-556
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Tidskriftsartikel (refereegranskat)abstract
- In a challenging situation some animals respond by active avoidance, aggression and an activation of the sympathetic nervous system whereas others respond by immobility, low levels of aggression and a predominant adrenocortical stress response. When consistent over time and across situations such inter-individual differences in behaviourul and physiological stress responses are referred to as stress coping strategies. In a previous study we reported the existence of two distinct stress coping strategies in a sea-ranched brown trout (Salmo trutta) population. Using the same method, we here show that four brown trout populations with different origin, but reared under identical conditions, differ in their endocrine stress response, behaviour during hypoxia and aggression. Further more, if individuals are classified as high- and low responsive based on post-stress blood plasma noradrenalin levels (indicator of sympathetic reactivity) the frequency distribution shows that populations with hatchery origin are biased towards having higher frequencies of high responsive individuals. However, the number of high responsive trout ranges from 14-48% in the different populations which shows that generally the frequency is biased towards lower levels of high responsive individuals. We discuss different frequency-dependent mechanisms that maintain multiple phenotypes in populations and speculate about differences in selection regime among the studied populations.
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| 33. |
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| 34. |
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| 35. |
- Brelin, Daniel, 1975-
(författare)
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Stress Coping Strategies in Brown Trout (Salmo Trutta): Ecological Significance and Effects of Sea-Ranching
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Two distinct stress coping strategies, proactive and reactive, have been stated in various animal studies, each associated with a set of behavioural and physiological characteristics. In a given challenging situation, proactive animals show more aggression, a higher general activity and a predominant sympathetic reaction. In contrast, the reactive copers respond more with immobility and avoidance, and a predominant parasympathetic/hypothalamic activation. This divergence in coping has also been indicated in salmonid fish. Interestingly, many of the differences reported between sea-ranched and wild fish resembles characteristics that differentiate proactive and reactive copers. In the present thesis it is shown that individuals with divergent stress coping styles are identifiable in several brown trout (Salmo trutta) populations. Further, the results show that the distribution of individuals displaying these distinct stress coping strategies differs between populations. This strongly indicates that these traits are heritable and that the variation in selection regime in the native rivers influences these traits. In addition, the results show that populations with hatchery origin are biased towards having higher frequencies of trout displaying a proactive style than populations having wild origin. Also, even though the frequency of early sexual maturation, known as a viable alternative life history in salmonids, differs between populations of brown trout, no link between stress coping strategy and early sexual maturation were found. However, this thesis show that maternal contribution, in the form of egg size, is of major importance whether the progeny will sexually mature early and that it also might be of importance for stress coping strategy. Further, correlations of traits commonly associated with stress coping strategies and behavioural syndromes across context and over time is investigated. The results show that individuals with a strong sympathetic reactivity are more prone to change their behaviour than others.
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| 36. |
- Cocco, Arianna, et al.
(författare)
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Characterization of the gamma-aminobutyric acid signaling system in the zebrafish (danio rerio hamilton) central nervous system by reverse transcription-quantitative polymerase chain reaction
- 2017
-
Ingår i: Neuroscience. - : Elsevier BV. - 0306-4522 .- 1873-7544. ; 343, s. 300-321
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Tidskriftsartikel (refereegranskat)abstract
- In the vertebrate brain, inhibition is largely mediated by raminobutyric acid (GABA). This neurotransmitter comprises a signaling machinery of GABA(A), GABA(B) receptors, transporters, glutamate decarboxylases (gads) and 4-aminobutyrate aminotransferase (abat), and associated proteins. Chloride is intimately related to GABAA receptor conductance, GABA uptake, and GADs activity. The response of target neurons to GABA stimuli is shaped by chloride-cation co-transporters (CCCs), which strictly control Cl- gradient across plasma membranes. This research profiled the expression of forty genes involved in GABA signaling in the zebrafish (Danio rerio) brain, grouped brain regions and retinas. Primer pairs were developed for reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The mRNA levels of the zebrafish GABA system share similarities with that of mammals, and confirm previous studies in non-mammalian species. Proposed GABAA receptors are alpha(1)beta(2)gamma(2), alpha(1)beta(2)delta, alpha(2b)beta(3), alpha(2b)beta(3)delta, alpha(4)beta(2)gamma(2), alpha(4)beta(2)gamma, alpha(6b)beta(2)gamma(2) and alpha(6b)beta(2)delta. Regional brain differences were documented. Retinal hetero- or homomeric rho-composed GABAA receptors could exist, accompanying alpha(1)beta(y)gamma(2), alpha(1)beta(y)delta, alpha(6a)beta(y)gamma(2,) alpha(6a)beta(y)delta. Expression patterns of alpha(6a) and alpha(6b) were opposite, with the former being more abundant in retinas, the latter in brains. Given the stoichiometry alpha(6w)beta(y)gamma(z), alpha(6a-) or alpha(6b)-containing receptors likely have different regulatory mechanisms. Different gene isoforms could originate after the rounds of genome duplication during teleost evolution. This research depicts that one isoform is generally more abundantly expressed than the other. Such observations also apply to GABAB receptors, GABA transporters, GABA-related enzymes, CCCs and GABAA receptor associated proteins, whose presence further strengthens the proof of a GABA system in zebrafish.
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| 37. |
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| 38. |
- Cocco, Arianna, 1989-, et al.
(författare)
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Neural expression patterns and protein modeling of the GABAA receptor ζ subunit in the adult zebrafish (Danio rerio Hamilton, 1822)
- 2018
-
Ingår i: Zebrafish. - 1545-8547 .- 1557-8542.
-
Tidskriftsartikel (refereegranskat)abstract
- The zebrafish has a repertoire of twenty-six GABAA receptor subunits, including the paralogues π and ζ, homologous to the mammalian π. The brain mRNA levels of the π subunit are low, but the ζ gene is actively transcribed in D. rerio central nervous system and retinas. With a combined quantitative and qualitative gene expression profiling approach, this research characterized the distribution of the ζ transcript in the brain and eyes of the adult zebrafish. It was demonstrated that there are regional brain differences in the production of this transcript, with the stratum periventriculare of the tecta mesencephali having the highest mRNA levels for ζ. In the adult zebrafish retinas the bipolar cell layer presented staining for the ζ transcript. The three-dimensional structure of the ζ subunit of the GABAA receptor in zebrafish was also calculated in this study, with the human β3 as template. It presented four transmembrane α-helices and an amino-terminal β-loop framed into a disulfide bridge. It was therefore possible to place ζ in the superfamily of Cys-loop membrane proteins, to which GABAA receptor subunits belong. The current study presented a thorough characterization of a unique fish GABAA receptor subunit, which might have specific functions only typical of fish.
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| 39. |
- Cocco, Arianna
(författare)
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The γ-aminobutyric acid and proton signaling systems in the zebrafish brain : Characterization and effect of stress
- 2018
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The central nervous system of vertebrates is continuously processing sensory information relayed from the periphery, integrating it and producing outputs transmitted to efferents. In the brain, neurons employ an array of messenger molecules to filter afferent information and finely regulate synaptic transmission. The γ-aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the adult vertebrate central nervous system, synthesized from α, L-glutamate by the glutamate decarboxylases (GADs). GABA promotes fast hyperpolarization of target cells mediated by the ionotropic, chloride-conducting type A GABA (GABAA) receptors. Those channels are homo- or heteropentamers and, in the zebrafish, at least twenty-three genes encode for putative GABAA receptor subunits.The present PhD thesis presents the expression levels of the almost complete panel of the GABA signaling machinery in the adult zebrafish brain and retinas. The results point toward GABA signaling modalities in zebrafish strikingly similar to those observed in mammals. The most common GABAA receptor subunit combinations in the whole brain were proposed to be α1β2γ2 and α1β2δ, and region-specific GABAA channels were also inferred. Those included telencephalic α2bβ3γ2, α2bβ3δ, α5β2γ2, α5β3γ2 and cerebellar α4β2γ2 and α4β2δ. A tissue specific expression was documented for the paralogues α6a and α6b; the former was abundantly transcribed in the retinas, the latter in the cerebellum. Proposed retinal GABAA receptors were α1βxγ2, α1βxδ, α6aβxγ2 and α6aβxδ, with either β2 or β3.Focus was also placed on functional aspects of the GABA signaling system in the adult zebrafish brain, and specifically on the effects of stress on GABAA receptor subunits expression. Treated animals experienced social isolation and repeated confinement, and depicted increased mRNA levels of several GABAA receptor monomers. It was deduced that a higher number of extrasynaptic, tonic-current-mediating GABAA channels was synthesized in the brain following stress. As synaptic transmission promotes extracellular acidification, interest was also placed on the acid-sensing ion channel (ASIC) subunits. The overall results presented in this PhD thesis point toward GABA and proton signaling systems in the zebrafish brain that have many common points with those of mammals. Thus, fundamental signaling pathways appear to be conserved across vertebrates.
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| 40. |
- Cubitt, K. Fiona, et al.
(författare)
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Social hierarchies, growth and brain serotonin metabolism in Atlantic salmon (Salmo salar) kept under commercial rearing conditions
- 2008
-
Ingår i: Physiology and Behavior. - : Elsevier BV. - 0031-9384 .- 1873-507X. ; 94:4, s. 529-535
-
Tidskriftsartikel (refereegranskat)abstract
- Monitoring social interactions between individuals in large, high-density groups poses several challenges. Here we demonstrate that relative concentrations of serotonin (5-Hydroxytryptamine, 5-HT) and its principal catabolite 5-Hydroxyindoleacetic acid (5-HIAA) in brain tissue of individual fish reflect social organisation in large groups of farmed Atlantic salmon. In the central nervous system of vertebrates, the monoamine neurotransmitter/neuromodulator 5-HT is critical for maintaining adaptive physiological, cognitive and emotional processes. In both teleost fish and mammals it has previously been shown that social interactions in small groups lead to elevated 5-HT release and/or metabolism in subordinate individuals, as indicated by the 5-HIAA/5-HT concentration ratio. In the current study, evidence is presented of non-linear dominance hierarchies in farmed Atlantic salmon (Salmo salar) kept at high rearing densities. The physiological effect of these hierarchies was decreased when food resources were abundant, although some subordinate fish still showed altered brain serotonergic activity and failed to grow even feed was available in excess. The largest effect of decreased feed rations was seen in fish of intermediate size, where competition appeared to increase with reduced access to feed. The largest individuals in each rearing unit showed low 5-HIAA/5-HT ratios independent of feeding regime. A novel observation, with respect to previous studies, was that elevated brain 5-HIAA/5-HT ratios resulted from decreased 5-HT concentrations rather than elevated 5-HIAA in small fish. Thus, in light of the serotonin deficit hypothesis of depression, it cannot be excluded that social stress is important for animal welfare even in large, relatively homogenous groups of animals reared in captivity.
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| 41. |
- Dahl, Emma, et al.
(författare)
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Geographic variation in corticosterone response to chronic predator stress in tadpoles
- 2012
-
Ingår i: Journal of Evolutionary Biology. - : Wiley. - 1010-061X .- 1420-9101. ; 25:6, s. 1066-1076
-
Tidskriftsartikel (refereegranskat)abstract
- Chronic stress often affects growth and development negatively, and these effects are often mediated via glucocorticoid hormones, which elevate during stress. We investigated latitudinal variation in corticosterone (CORT) response to chronic predator stress in Rana temporaria tadpoles along a 1500-km latitudinal cline in Sweden tadpoles, in a laboratory experiment. We hypothesized that more time-constrained high-latitude populations have evolved a lower CORT response to chronic stress to maintain higher growth under stressful conditions. Southern tadpoles had higher CORT content in response to predators after 1 day of exposure, whereas there was no increase in CORT in the northern populations. Two weeks later, there were no predator-induced CORT elevations. Artificially elevated CORT levels strongly decreased growth, development and survival in both northern and southern tadpoles. We suggest that the lower CORT response in high-latitude populations can be connected with avoidance of CORT-mediated reduction in growth and development, but also discuss other possible explanations.
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| 42. |
- Dahl, Emma, et al.
(författare)
-
Is growth hormone expression correlated with variation in growth rate along a latitudinal gradient in Rana temporaria?
- 2011
-
Ingår i: Journal of Zoology. - : Wiley. - 0952-8369 .- 1469-7998. ; 285:2, s. 85-92
-
Tidskriftsartikel (refereegranskat)abstract
- In ectotherms, decreasing season length and lower temperature towards higher latitudes often favour higher growth and developmental rates. However, the underlying physiological mechanisms and particularly the hormonal correlates of clinal variation remain unexplored. The growth hormone (GH) plays a crucial role in growth of all vertebrates and high expression of GH is associated with rapid growth in many species. We tested the hypothesis that GH expression is correlated with a latitudinal gradient in growth in Scandinavian Rana temporaria tadpoles. Using quantitative polymerase chain reaction, we measured GH and growth hormone receptor (GHR) expression at two time points from laboratory-raised tadpoles originating from eight populations collected along the latitudinal gradient. To explore latitudinal differences in stress-induced changes in GH expression, we also compared GH expression in tadpoles raised with and without predators. In accordance with previous studies we found a clear latitudinal gradient in growth. There were no latitudinal effects, or predator-induced effects on GH or GHR expression. However, there was some indication for among-population variation in GH expression. The lack of a latitudinal pattern in GH and GHR expression may be due to that the growth promoting effects of GH is dependent on other factors including insulin-like growth factor-I (IGF), IGF-binding proteins or prolactin. Further studies on these factors may provide insight on the proximal mechanisms of differences in growth in R. temporaria tadpoles.
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| 43. |
- Dahlbom, Josefin, et al.
(författare)
-
Boldness predicts social status in zebrafish (Danio rerio)
- 2011
-
Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 6:8
-
Tidskriftsartikel (refereegranskat)abstract
- This study explored if boldness could be used to predict social status. First, boldness was assessed by monitoring individual zebrafish behaviour in (1) an unfamiliar barren environment with no shelter (open field), (2) the same environment when a roof was introduced as a shelter, and (3) when the roof was removed and an unfamiliar object (Lego® brick) was introduced. Next, after a resting period of minimum one week, social status of the fish was determined in a dyadic contest and dominant/subordinate individuals were determined as the winner/loser of two consecutive contests. Multivariate data analyses showed that males were bolder than females and that the behaviours expressed by the fish during the boldness tests could be used to predict which fish would later become dominant and subordinate in the ensuing dyadic contest. We conclude that bold behaviour is positively correlated to dominance in zebrafish and that boldness is not solely a consequence of social dominance.
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| 44. |
- Dahlbom, S. Josefin, et al.
(författare)
-
Aggression and monoamines : Effects of sex and social rank in zebrafish (Danio rerio)
- 2012
-
Ingår i: Behavioural Brain Research. - : Elsevier BV. - 0166-4328 .- 1872-7549. ; 228:2, s. 333-338
-
Tidskriftsartikel (refereegranskat)abstract
- Social defeat is a common model for studies on depression. However, such models are most often used to study aggression in males and sex differences in depression may therefore be overseen. This study investigated the potential of the zebrafish (Danio rerio) as a model for male and female aggression. In addition, effects on the brain serotonergic and dopaminergic neurotransmitter systems after agonistic interaction are well studied in many species, but not in zebrafish. We wanted to explore whether the zebrafish follows the same patterns as many other species. Therefore, the effects of agonistic interaction on brain monoaminergic activity were studied in adult male and female wild-type zebrafish. The fish interacted in pairs with one of the same sex for five days during which agonistic behaviour was quantified daily. Clear dominant/subordinate relationships developed in all pairs, both in males and females. The frequency of aggressive acts increased over time but did not differ between male and female pairs. Further, we found that dyadic agonistic interaction resulted in elevated brain serotonergic activity in subordinate zebrafish, as indicated by elevated hindbrain 5-hydroxyindoleacetic acid to serotonin ratios (5-hydroxyindolacetic acid (5-HIAA)/5-hydroxytryptamine (5-HT) ratios). We also observed a sex difference in forebrain dopamine levels and forebrain 5-HIAA/5-HT ratios, with females displaying higher concentrations of dopamine but lower 5-HIAA/5-HT ratios than males. These results suggest that zebrafish is a suitable model for studies on female aggression and sex differences in brain monoaminergic neurotransmission.
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| 45. |
- Dahlbom, S Josefin
(författare)
-
Bully or Bullied? : The Zebrafish as a Model for Social Stress and Depression
- 2013
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The zebrafish is evaluated as a model for social stress, depression and anxiety. I conclude that it is suitable, especially for studies of sex differences. In humans, women are more prone to depression but most animal studies are performed in males. A popular way to study depression is by means of social stress, which is often a contributing factor to depression. However, social stress in female rodents is difficult to study since female aggression is mostly limited to maternal defence. Thus, there is a need for models to study depression and anxiety in females, as well as sex differences in these disorders.As personality is a risk factor for developing depression, I aimed at exploring correlated behaviours that together characterise personalities. My work confirmed that zebrafish, as numerous other species, show strong correlations between boldness and aggression on the one hand, and neurobiological reactions to social stress on the other. In general, males were bolder than females, but there were no differences in aggressive behaviours between the sexes. It was also confirmed that both acute and chronic social stress activates the dopamine and serotonin systems in the brain, and that subordinate individuals appear to be more stressed, based on serotonergic activity.Further, I studied the consequences of altered levels of serotonin during development, such as would be the case when antidepressants are used during pregnancy. Zebrafish embryos were treated with drugs that affect the serotonin system by increasing or decreasing serotonin levels. Depletion of serotonin increased the expression of several serotonin-related genes but had no effect on morphology. In contrast, increasing serotonin levels only showed small effects on gene expression, but increased the length of the myotomes in the spinal cord. Together with other studies, my results indicate that fluvoxamine might be a suitable choice for treatment of depression during pregnancy.In conclusion, my results show that the zebrafish is a valid model organism for studying social stress, depression and anxiety disorders and it should therefore be considered when developing new animal models for depression. It will especially be beneficial in studies of sex differences.
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| 46. |
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| 47. |
- de Abreu, Murilo S., et al.
(författare)
-
Dopamine and serotonin mediate the impact of stress on cleaner fish cooperative behavior
- 2020
-
Ingår i: Hormones and Behavior. - : ACADEMIC PRESS INC ELSEVIER SCIENCE. - 0018-506X .- 1095-6867. ; 125
-
Tidskriftsartikel (refereegranskat)abstract
- Stress is known to modulate behavioral responses and rapid decision-making processes, especially under challenging contexts which often occur in social and cooperative interactions. Here, we evaluated the effects of acute stress on cooperative behavior of the Indo-Pacific cleaner wrasse (Labroides dimidiatus) and the implications of pre-treatment with monoaminergic compounds: the selective serotonin reuptake inhibitor - fluoxetine, the 5-HT1A receptor antagonist - WAY-100,635, the D-1 receptor agonist - SKF-38393, and the D-1 receptor antagonist - SCH-23390. We demonstrated that stress decreased the predisposal to interact and increased cortisol levels in cleaners, which are alleviated by fluoxetine and the dopaminergic D-1 antagonist. Overall, our findings highlight the crucial influence of stress on cooperative behavior.
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| 48. |
- de Abreu, Murilo S., et al.
(författare)
-
The variable monoaminergic outcomes of cleaner fish brains when facing different social and mutualistic contexts
- 2018
-
Ingår i: PeerJ. - : PEERJ INC. - 2167-8359. ; 6
-
Tidskriftsartikel (refereegranskat)abstract
- The monoamines serotonin and dopamine are important neuromodulators present in the central nervous system, known to be active regulators of social behaviour in fish as in other vertebrates. Our aim was to investigate the region-specific brain monoaminergic differences arising when individual cleaners face a client (mutualistic context) compared to when they are introduced to another conspecific (conspecific context), and to understand the relevance of visual assessment compared to the impact of physical contact with any partner. We demonstrated that serotoninergic activity at the diencephalon responds mostly to the absence of physical contact with clients whereas cerebellar dopaminergic activity responds to actual cleaning engagement. We provide first insights on the brain's monoaminergic (region-specific) response variations, involved in the expression of cleaner fishes' mutualistic and conspecific behaviour. These results contribute to a better understanding of the monoaminergic activity in accordance to different socio-behavioural contexts.
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| 49. |
- Dimitriadou, S., et al.
(författare)
-
Brain monoaminergic activity during predator inspection in female Trinidadian guppies (Poecilia reticulata)
- 2023
-
Ingår i: Behavioural Brain Research. - : Elsevier. - 0166-4328 .- 1872-7549. ; 436
-
Tidskriftsartikel (refereegranskat)abstract
- To understand the processes underpinning social decision-making, we need to determine how internal states respond to information gathered from the social environment. Brain monoamine neurotransmitters are key in the appraisal of the social environment and can reflect the internal state underlying behavioural responses to social stimuli. Here we determined the effects of conspecific partner cooperativeness during predator inspection on brain monoamine metabolic activity in Trinidadian guppies (Poecilia reticulata). We quantified the concentration of dopamine, serotonin and their metabolites across brain sections sampled immediately after ostensibly expe-riencing cooperation or defection from social partners whilst inspecting a predator model, using a familiar object as a control condition. Our results indicate dopaminergic and serotonergic activity differs with the coopera-tiveness experienced; these different neurotransmission profiles are likely to affect the expression and regulation of downstream behaviours that ultimately contribute to the patterning of cooperative interactions among in-dividuals in a population.
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| 50. |
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