| 1. |
- Titulaer, Joep
(författare)
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Finding improved drug strategies for schizophrenia : Preclinical studies on lumateperone and sodium nitroprusside
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Schizophrenia is a severe psychiatric disorder affecting approximately 20 million people worldwide. The disease consists of positive symptoms e.g. hallucinations, negative symptoms such as anhedonia, and cognitive deficits, e.g. impaired episodic memory. Most of the currently available treatment options for schizophrenia only target the positive symptoms, possess severe side effects and do not work for a large group of patients. In this thesis, the unique antipsychotic drug lumateperone and adjunctive treatment of sodium nitroprusside (SNP) to sub-maximal doses of conventional antipsychotic drugs are investigated in preclinical tests as novel treatment options for schizophrenia In paper I we showed that SNP enhances the antipsychotic-like effect of a sub-effective dose of risperidone in the conditioned avoidance response (CAR) test in rats. Moreover, by using microdialysis we showed that SNP significantly enhances risperidone-induced dopamine release in the rat medial prefrontal cortex (mPFC) but not in the nucleus accumbens, indicating that adjunct SNP could be used to improve the efficacy of antipsychotic drugs, while reducing their dose and subsequently lower the risk of side effects.In paper II we used microdialysis combined to the behavioral novel object recognition test in rats to show that the release of both dopamine and norepinephrine is increased in the ventral hippocampus in response to a novel object, suggesting that dopamine and norepinephrine may play a crucial role in recognition memory. In paper III we showed that SNP significantly enhanced the antipsychotic-like effect of sub-effective doses of olanzapine in the CAR test, but not of clozapine, this could be explained by the developed tolerance towards clozapine after repeated administrations.In paper IV we used enzyme-coated microelectrode arrays to show that lumateperone significantly increased cortical glutamate release in the mPFC of anaesthetized rats. By using electrophysiology, we also show that lumateperone facilitates NMDA and AMPA-mediated currents in a dopamine D1 dependent manner in layer V/VI pyramidal neurons in the mPFC of rats. Moreover, lumateperone increases dopamine release in the mPFC of freely moving rats as shown by using microdialysis. These mechanisms may improve cognitive deficits and contribute to the clinically demonstrated antidepressant effects of lumateperone. Taken together, these results show that lumateperone is a promising novel treatment option for schizophrenia, and that adjunct SNP treatment may allow for improved efficacy at maintained or even reduced dosage of conventional antipsychotic medication.
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| 2. |
- Karlsson, Oskar, 1980-
(författare)
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Distribution and Long-term Effects of the Environmental Neurotoxin β-N-methylamino-L-alanine (BMAA) : Brain changes and behavioral impairments following developmental exposure
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Many cyanobacteria are reported to produce the nonprotein amino acid β-N-methylamino-L-alanine (BMAA). Cyanobacteria are extensively distributed in terrestrial and aquatic environments and recently BMAA was detected in temperate aquatic ecosystems, e.g. the Baltic Sea. Little is known about developmental effects of the mixed glutamate receptor agonist BMAA. Brain development requires an optimal level of glutamate receptor activity as the glutamatergic system modulates many vital neurodevelopmental processes. The aim of this thesis was to investigate the developmental neurotoxicity of BMAA, and its interaction with the pigment melanin. Autoradiography was utilized to determine the tissue distribution of 3H-labelled BMAA in experimental animals. Behavioral studies and histological techniques were used to study short and long-term changes in the brain following neonatal exposure to BMAA. Long-term changes in protein expression in the brain was also investigated using matrix-assisted laser desorption ionization (MALDI) imaging mass spectrometry (IMS). A notable targeting of 3H-BMAA to discrete brain regions e.g. hippocampus and striatum in mouse fetuses and neonates was determined by autoradiography. BMAA treatment of neonatal rats on postnatal days 9–10 induced acute but transient ataxia and hyperactivity. Postnatal exposure to BMAA also gave rise to reduced spatial learning and memory abilities in adulthood. Neonatal rat pups treated with BMAA at 600 mg/kg showed early neuronal cell death in the hippocampus, retrosplenial and cingulate cortices. In adulthood the CA1 region of the hippocampus displayed neuronal loss and astrogliosis. Lower doses of BMAA (50 and 200 mg/kg) caused impairments in learning and memory function without any acute or long-term morphological changes in the brain. The MALDI IMS studies, however, revealed changes in protein expression in the hippocampus and striatum suggesting more subtle effects on neurodevelopmental processes. The studies also showed that BMAA was bound and incorporated in melanin and neuromelanin, suggesting that pigmented tissues such as in the substantia nigra and eye may be sequestering BMAA. In conclusion, the findings in this thesis show that BMAA is a developmental neurotoxin in rodents. The risks posed by BMAA as a potential human neurotoxin merits further consideration, particularly if the proposed biomagnifications in the food chain are confirmed.
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| 3. |
- Lundberg, Stina, 1990-
(författare)
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Adolescent behavior : Links to early-life stress and alcohol in male and female rats
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Adolescence is an important developmental phase with large changes in behavior, physiology and neurobiology, which transform an individual from immature child to independent adult. Due to these changes, adolescence is a sensitive period for exposure to environmental factors such as stress and drug exposure; it is also a common age of onset for alcohol consumption as well as several psychiatric disorders. Despite these factors, less is known about this developmental period than regarding adult individuals. Behavior is regulated by the central nervous system and can be used as a lens to study these processes as well as for examination of associations between individual differences, early-life stress and alcohol. The aim of this thesis was to experimentally examine adolescent behavior and its links to early-life stress and alcohol in adolescent male and female rats. Different behavioral tests were used to profile adolescent animals together with animal models of early-life stress, voluntary alcohol consumption and alcohol exposure. In addition, stress responsiveness after early-life stress and the impact of alcohol exposure on endogenous opioid peptide levels as well as blood alcohol concentrations were examined. The adolescent behavioral profile in the multivariate concentric square field™ (MCSF) was characterized and validated against the elevated plus maze and open field tests. The main finding was subgroups based on individual variation that revealed three distinct behavioral types: Explorers, Shelter seekers and Main type animals. This pattern was replicated in an additional, independent cohort. Early-life stress, modelled by prolonged maternal separation, showed small effects on behavior in the MCSF and on social play behavior. However, an effect on stress responsiveness in males but not females subjected to prolonged maternal separation was discovered. Predisposition for high alcohol consumption did not have a shared behavioral profile among selectively bred rat lines. However, a subgroup of high drinking individuals in an outbred cohort showed behavioral similarities to one of the selectively bred lines. Alcohol exposure showed small, but sex-dependent, effects on behavior and endogenous opioid peptide levels. Together, these studies provide new information about adolescent behavior and associations to early-life stress and alcohol in males and females, relationships not extensively studied in adolescence.
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| 4. |
- Granholm, Linnea
(författare)
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Neurobiological Consequences of Social Conditions and Alcohol Exposure in Adolescent rats
- 2015
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Adolescence represents a time of extensive reorganisation and maturation of brain circuits involved in emotions, motivation and cognition and it is a period particular sensitive for external stimuli. External stimuli can be both socio-environmental factors and exposure to exogenous compounds such as drugs of abuse (e.g. alcohol). If these stimuli are of an adverse nature the probability of develop neuropsychiatric diseases or addiction is increased. To study the neurobiological consequences of adverse events during adolescence animal models are crucial since they give the opportunity of providing an environment where the exposure of the stimuli is controlled and also enable a detailed analysis of the effects in the brain. The overall aim of in this thesis was to investigate how environmental factors, social conditions or alcohol exposure, during adolescence affect the brain and/or drug-taking in rats. Rats are very sensitive for dis- turbances in their social conditions and to induce an adverse social environment, early adolescent rats where single-housed for either a short or prolonged time. A short period of single housing induced an acute stress response and increased levels of nociceptin/orphanin FQ in brain areas associated with stress. Prolonged single housing reduced the levels of Met-enkephalin-Arg6Phe7 in several brain areas. Rats exposed to alcohol during adolescence had an altered dopamine response in dorsal striatum after an am- phetamine challenge but displayed similar amphetamine intake-behaviour as water controls. However, animals exposed to a combination of adolescent alcohol exposure and subsequent amphetamine intake had a more efficient removal of dopamine in dorsal striatum after an amphetamine challenge. This thesis demonstrates how two different environmental stimuli are able to alter the neurobiology in adolescent rats. The results further support the notion that environmental conditions are of importance for normal brain maturation and provide new evidence that endogenous opioids are severely affected by social dis- turbances during adolescence. Furthermore, additional information is provided to the existing literature of how alcohol exposure during adolescence affects dopamine dynamics and drug-taking behaviour. In the literature, the majority of the studies of adolescent alcohol exposure have focused on the nucleus accum- bens, a brain area important in the processing of rewards. The results herein provide evidence that dorsal striatum, a brain area involved in the transition into habitual drug use is also affected by adolescent alco- hol exposure. An altered drug response in dorsal striatum may affect habit formation and contribute to a heightened susceptibility for high drug consumption later in life.
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| 5. |
- Granholm, Linnea, 1986-
(författare)
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Stress, Drugs and Neuroscience : Neurobiological Effects of Social Stressors and Drug Exposure in Young and Adolescent Rats
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Experiences early in life or during adolescence modulate neuronal networks in the immature brain and consequently lay the foundation for future susceptibility or resilience towards psychiatric disorders. The objective in this thesis is to understand, in part, how the surrounding environment shapes the brain of a young individual. Three types of negative life events were studied, in an animal model, for their effects on the brain reward system (i.e., endogenous opioids and dopamine) and voluntary drug intake. These were: disruption of maternal care, disruption of interaction with peers, and exposure to drugs. Stress, in the form of maternal separation, altered expression of opioid genes in the dorsal striatum and amygdala, and the response to subsequent alcohol intake on these genes was dependent on early life conditions. Basal levels of endogenous opioids were also dependent on how the animals were housed in early adolescence. Short single housing (30 minutes) caused an acute stress response as evidenced by increased serum corticosterone and nociceptin/orphanin FQ in brain areas associated with stress. A prolonged single housing resulted in a marked decrease of Met-Enk-Arg6-Phe7 (i.e., a marker of enkephalins) in several brain areas. The endogenous opioids were also affected by repeated exposure of ethanol during adolescence; ethanol intoxication increased the accumbal levels of Met-Enk-Arg6-Phe7 and decreased those of β-endorphin. Residual effects of the adolescent ethanol exposure were found in Met-Enk-Arg6-Phe7 levels in the amygdala, ventral tegmental area, and substantia nigra. Furthermore, rats exposed to ethanol as adolescents had alterations in the dopamine dynamics in the dorsal striatum. Both endogenous opioids and dopamine are essential in mediating rewarding properties. Alterations of these systems, caused by environmental disturbances and alcohol exposure, presented herein could explain, in part, the increased susceptibility for alcohol- and substance use disorders later in life.
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| 6. |
- Lindberg, Frida A.
(författare)
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The Biological Importance of the Amino Acid Transporter SLC38A10 : Characterization of a Knockout Mouse
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The biggest group of transporters, the solute carriers (SLCs), has more than 400 members, and about 30% of these are still orphan. In order to decipher their biological function and possible role in disease, there is a need for characterization of these. Around 25% of SLCs are estimated to have amino acids as substrates, including transporters belonging to the SLC38 family. The SLC38 members are sometimes referred to their alternative name: sodium-coupled neutral amino acid transporters (SNATs). One of these transporters, SNAT10 (or SLC38A10), has been characterized as a bidirectional transporter of glutamate, glutamine, alanine and aspartate, as well as having an efflux of serine, and is ubiquitously expressed in the body. However, its biological importance is not yet understood. The aim with this thesis was to characterize a mouse model deficient in SNAT10 protein in order to find the biological importance of this transporter. In paper I, this is done by using a series of behavioral tests, including the open field test, elevated plus maze, rotarod and Y-maze, among others. The SNAT10 knockout mouse was found to have an increased risk-taking behavior, but no motor or spatial working memory impairments. Furthermore, the knockout mouse was found to have a decreased body weight. In paper II, an additional behavioral characterization was performed by using the multivariate concentric square field™ (MCSF) test. The MCSF test is an arena with different zones associated to different behavioral traits, which generates a behavioral profile depending on where the mouse spends its time. The result from this test implies that the SNAT10 deficient mouse has a lower explorative behavior than its wild type littermates. In paper III, gene expression was studied in whole brain and some genes related to cell cycle regulation and p53 expression were found to be differentially expressed in the knockout brain. Additional gene expression was studied in kidney, liver, lung and muscle, but no changes were found. Plasma levels of histidine and threonine were altered in males, but no altered amino acid levels were found in knockout females, suggesting a possible sex-specific effect. These studies together imply that SNAT10 might be involved in processes related to risk-taking and explorative behavior in the open field and MCSF tests. SNAT10 deficiency also affected amino acid levels in plasma, indicating a disrupted amino acid homeostasis.
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| 7. |
- Tjernström, Nikita, 1992-
(författare)
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Strategies in the rat gambling task : Individual differences in decision-making and associations to behavior, neurobiology and human strategies
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Gambling disorder (GD) is a behavioral addiction characterized by persistent and recurrent gambling behavior that disrupts personal, social or professional life. Studies have revealed that GD shares many features with alcohol and substance use disorders, but little is known about potential unique features in GD and to what extent characteristics are shared. One shared feature is reward-related decision-making and individuals with GD display deficits in decision-making. The rat gambling task (rGT) has been developed to enable preclinical studies of reward-related decision-making and underlying neurobiological mechanisms.The aim of this thesis was to explore individual differences in decision-making strategies in the rGT and underlying behavioral phenotypes and neurobiology.Paper I: three groups with different decision-making strategies in the rGT were identified: the strategic, risky and safe group. The rGT strategies were shown to be stable over time, even after multiple interruptions and other behavioral testing. Rats with risky rGT strategies had higher voluntary alcohol intake but not elevated sexual behavior. Naltrexone treatment resulted in an overall lowered motivation in the rGT but had no effect on choice behavior.Paper II: individual differences in gambling strategies were found in the rGT and corresponding strategy groups were replicated from Paper I. Moreover, brain functional connectivity was assessed using resting-state functional Magnetic Resonance Imaging. Differences in rGT strategies were associated with connectivity in regions in or associated with brain reward networks.Paper III: levels of neurotransmitters and metabolites were explored using matrix-assisted laser desorption/ionization mass spectrometry imaging in selected brain regions. The strategy groups were revealed to differ in levels of neurotransmitters and metabolites in regions of importance for decision-making and reward.Paper IV: decision-making strategies in humans, using the Iowa gambling task, and in rats, using the rGT, were explored. Results showed that most humans and rats learned to favor the advantageous choices and showed similar variability in individual choice preferences during end performance.This thesis has provided new information about individual decision-making strategies in the rGT and associations with other reward-related behaviors as well as neurobiology. Characterization of the strategy groups indicates a shared underlying mechanism between rGT strategies and alcohol intake but not natural rewards. Neurobiological differences in regions important for reward processing were also revealed. Lastly, similar variability in individual choice preference was found in humans and rats and it is concluded that both clinical and preclinical research would benefit from more detailed analyses on individual variations in decision-making.
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| 8. |
- Daoura, Loudin
(författare)
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Early Environment and Adolescent Ethanol Consumption : Effects on Endogenous Opioids and Behaviour in Rats
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Excessive and compulsive ethanol drinking is one of the most serious public health issues. Therefore, it is vital to increase the knowledge about risks and protection for alcohol use disorders (AUD) to optimize prevention and treatment strategies. Ethanol consumption commonly initiates during adolescence when extensive neuronal maturation and development also occurs. Early exposure to ethanol is a risk factor for AUD, but the effects of adolescent drinking and the basis for the individual susceptibility to AUD are not fully understood. The interactions between genotype and environmental factors determine the individual risk for AUD and this thesis aimed to examine the environmental impact. The specific aims were to investigate 1) how early-life conditions affect adolescent voluntary ethanol drinking, behavioural profiles, endogenous opioids and response to treatment with an opioid antagonist (naltrexone), and 2) whether alterations detected in the offspring may be mediated by variations in maternal behaviour. A rodent maternal separation (MS) model was used to mimic a protective and risk-inducing early-life environment, respectively, with the use of 15 min (MS15) or 360 min (MS360) of daily MS. The main findings were 1) the MS360, but not the MS15 rats, responded to naltrexone following adolescent ethanol drinking; all adolescent rats had a high voluntary ethanol intake independent of early environmental conditions whereas in the adult groups the MS360, but not the MS15 rats, increased their ethanol intake and preference over time; adolescent ethanol exposure resulted in higher dynorphin levels in hippocampus and higher Met-enkephalin-Arg6Phe7 in the amygdala, independently of rearing conditions, 2) behavioural profiling using the multivariate concentric square field™ test showed: the young MS360 rats had increased risk assessment and risk taking behaviour compared to the young MS15 rats; the young MS15 rats increased, whereas the young MS360 rats decreased, their risk assessment and risk taking behaviour over time; differences in pup-retrieval strategies where the MS360 dams retrieved some pups into a safe area but as compared to MS15 rats they left more pups in a risk area; increased risk assessment behaviour in the MS360 dams immediately after weaning. Taken together, early-life environmental conditions alter adult but not adolescent drinking, the response to naltrexone, and behaviour in dams and offspring. Adolescent rats consumed more ethanol independent of rearing conditions and displayed increased opioid levels in brain areas related to cognition and addiction.
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| 9. |
- Fanni, Giovanni, et al.
(författare)
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Effects of gastric bypass surgery on brain connectivity responses to hypoglycemia
- 2023
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Ingår i: Endocrine. - : Springer Nature. - 1355-008X .- 1559-0100 .- 0969-711X. ; 79:2, s. 304-312
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Tidskriftsartikel (refereegranskat)abstract
- IntroductionRoux-en-Y gastric bypass (RYGB) leads to beneficial effects on glucose homeostasis, and attenuated hormonal counterregulatory responses to hypoglycemia are likely to contribute. RYGB also induces alterations in neural activity of cortical and subcortical brain regions. We aimed to characterize RYGB-induced changes in resting-state connectivity of specific brain regions of interest for energy homeostasis and behavioral control during hypoglycemia.MethodTen patients with BMI > 35 kg/m2 were investigated with brain PET/MR imaging during a hyperinsulinemic normo- and hypoglycemic clamp, before and 4 months after RYGB. Hormonal levels were assessed throughout the clamp. Resting-state (RS) fMRI scans were acquired in the glucose-lowering phase of the clamp, and they were analyzed with a seed-to-voxel approach.ResultsRS connectivity during initiation of hypoglycemia was significantly altered after RYGB between nucleus accumbens, thalamus, caudate, hypothalamus and their crosstalk with cortical and subcortical regions. Connectivity between the nucleus accumbens and the frontal pole was increased after RYGB, and this was associated with a reduction of ACTH (r = −0.639, p = 0.047) and cortisol (r = −0.635, p = 0.048) responses. Instead, connectivity between the caudate and the frontal pole after RYGB was reduced and this was associated with less attenuation of glucagon response during the hypoglycemic clamp (r = −0.728, p = 0.017), smaller reduction in fasting glucose (r = −0.798, p = 0.007) and less excess weight loss (r = 0.753, p = 0.012). No other significant associations were found between post-RYGB changes in ROI-to-voxel regional connectivity hormonal responses and metabolic or anthropometric outcomes.ConclusionRYGB alters brain connectivity during hypoglycemia of several neural pathways involved in reward, inhibitory control, and energy homeostasis. These changes are associated with altered hormonal responses to hypoglycemia and may be involved in the glucometabolic outcome of RYGB.
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| 10. |
- Gustafsson, Lisa, 1975-
(författare)
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Endogenous Opioids and Voluntary Ethanol Drinking : Consequences of Postnatal Environmental Influences in Rats
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Genetic and environmental factors interact to determine the individual vulnerability to develop ethanol dependence. The neurobiological mechanisms underlying these processes are not fully understood. Endogenous opioid peptides have been suggested to contribute. Brain opioids mediate ethanol reward and reinforcement via actions on the mesocorticolimbic dopamine system. This thesis focuses on environmental factors and investigates the impact of the early-life environment on adult voluntary ethanol consumption. The possible involvement of opioid peptides in environmental influences on adult ethanol consumption was examined using an experimental animal model. Maternal separation with short 15 min separations (MS15) was used to simulate a safe environment whereas prolonged 360 min separations (MS360) simulated an unsafe environment. Control rats were subjected to normal animal facility rearing (AFR). The separations were performed daily from postnatal day 1 to 21. Long-term ethanol consumption was registered using a two-bottle or a four-bottle free-choice paradigm in adult male and female ethanol-preferring AA (Alko, Alcohol), ethanol-avoiding ANA (Alko, Non-Alcohol) and non-preferring Wistar rats. In addition, analyses of immunoreactive Met-enkephalin-Arg6Phe7 (MEAP), dynorphin B (DYNB) and nociceptin/orphanin FQ (N/OFQ) peptide levels were performed after maternal separation as well as after voluntary ethanol drinking. In male rats, MS15 was related to lower ethanol consumption and these rats preferred lower concentrations, whereas MS360 was associated with an increased risk for higher consumption and/or preference for higher ethanol concentrations. Differences in basal opioid levels were observed in MS15 and MS360 rats. Furthermore, the ethanol-induced effects on opioid peptides in adults were dependent on the early environment. Female rats, on the other hand, were less affected or unaffected by maternal separation both in terms of ethanol consumption and neurobiological effects. Taken together, voluntary ethanol drinking, preference for low or high ethanol concentrations and opioid peptides in brain areas related to reward and reinforcement, motivation and stress were influenced by postnatal maternal separation in a sex dependent manner. The early environment thus had profound impact on the adult brain and the individual propensity for high ethanol drinking. A deranged endogenous opioid system contributed to these effects and may act as a mediator for long-term environmental influence on voluntary ethanol consumption.
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| 11. |
- Lundberg, Stina
(författare)
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Examining Female Resilience to Early Environmental Influences : Short- and long-term consequences on behaviour, HPA axis activity and alcohol intake after prolonged maternal separation
- 2017
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Early-life experiences are an important factor influencing further development of the individual. Adverse experiences early in life, such as various kinds of abuse or neglect, are types of early-life stress that can adversely affect an individuals health, as well as contribute to the development of an array of disorders later in life. Most prominent is the increased risk for psychiatric disorders, primarily depression, anxiety-related and substance use disorders. Many of the implicated disorders also exhibit sex-dependent differences in prevalence and severity. Thus, it is important to consider sex-dependent effects when modeling early-life stress and its consequences. A common animal model for early-life stress is prolonged maternal separation (MS). MS is an umbrella term for different manipulations of the early environment of rodent pups. In this thesis, a prolonged MS condition with separation of rat litters from their dams for six hours per day during the first three weeks of life (MS360) was used. In male offspring MS360 have been associated with early-life stress and negative effects apparent during both adolescence and adulthood. The literature regarding female offspring is not as substantial as for the males, but it seems that females’ exhibit less pronounced or no effect after prolonged MS independent of separation time. In addition, the studies that have examined female offspring have done so in adulthood and thus, short-term consequences of prolonged MS possibly present during adolescence have not been investigated. The aim of this thesis is to provide a broad investigation into the consequences of prolonged MS in female offspring, in both adolescence and adulthood. As stated above, MS360 was used as the adverse rearing condition in this thesis. As control, daily short MS (15 min; MS15) was used; this ensured that all animals were handled equally, except for the length of separation. Any detected differences are thus due to the length of separation only. Three categories of assessments were used to evaluate short- and long-term consequences: 1) hypothalamus-pituitary-adrenal (HPA) axis assessments, 2) behavioral assessments and 3) assessment of voluntary alcohol consumption. HPA axis reactivity was assessed in adolescent and adult offspring by blood sampling before and after challenge. HPA activity was also evaluated after long-term alcohol consumption by measurement of the fecal corticosterone content. Behavior was assessed in adolescence by registration of social play behavior and in adulthood by generation of behavioral profiles in the multivariate concentric square fieldTM (MCSF). Alcohol consumption was evaluated using the modified intermittent alcohol access schedule with the two- (20% alcohol) and three- bottle (5% and 20% alcohol) free-choice paradigms. Female offspring did not differ depending on rearing condition in HPA reactivity in adolescence or adulthood. However, after the long-term alcohol intake, MS360 females had increased levels of corticosterone in their feces compared to MS15 females. No difference was detected in adolescent social play among female offspring and only a minor alteration was detected in the adult behavioral profile, where MS360 females had increased risk assessment compared to MS15 females. No effect of rearing condition was seen during the two-bottle choice paradigm of alcohol intake, while whole- group differences over time were discovered. Alcohol intake and preference were highest the first week of access and directly after a two-week deprivation period, apart from those time-points, intake and preference were maintained on a stable level. In the three-bottle choice, an interaction with rearing condition was revealed for the total alcohol preference, however this only translated to a minor group-dependent difference. In conclusion, females reared under a prolonged MS paradigm exhibited no or only minor basal changes in HPA axis reactivity, behavior and alcohol consumption. However, after long-term alcohol intake females subjected to prolonged MS had increased corticosterone excretion into feces. That differences only emerge after long-term perturbation can be a sign that females have higher buffering capabilities than males after early-life adversity, as modeled through prolonged MS, and thus require additional challenges before consequences become apparent. This thesis highlights the importance of considering sex when studying the impact of early-life stress, and that the choice of animal model needs to be considered carefully in relation to the research question posed.
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| 12. |
- Momeni, Shima
(författare)
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Individual differences in behavior, neurochemistry and pharmacology associated with voluntary alcohol intake
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Alcohol use disorder is a worldwide public health problem and is a disorder with substantial individual variation. There are suggested links between various behavioral traits, comorbid psychiatric diseases and excessive alcohol consumption. Moreover, the endogenous opioid system is involved in alcohol reward and reinforcement, and implicated in the action of alcohol. However, less is known about the complex associations between individual differences in behavior, alcohol consumption, pharmacotherapy response and related neurochemical mechanisms. Experimental animal models are critical for understanding the neurobiological underpinnings of alcohol use disorder.The overall aims of this thesis were: i) to study the association between behavior and voluntary alcohol intake in outbred rats; ii) to study the association of voluntary alcohol intake, behavior, opioid receptor density and response to naltrexone; and iii) to obtain detailed behavioral characterizations of the animals on the basis of their voluntary alcohol intake.The results revealed that the multivariate concentric square fieldTM (MCSF) test was a complementary method for understanding mechanisms underlying various mental states. The MCSF broadened the perspective on risk-related behaviors, including aspects of risk assessment. Individual differences in alcohol intake using the modified intermittent access paradigm enabled analyses of drinking patterns in high and low alcohol-drinking rats. There was an alcohol deprivation effect in high-drinking animals only. The behavior profiling of high alcohol drinking- rats before and after alcohol access suggested that this subgroup was consuming alcohol for its anxiolytic properties. Long-lasting changes were found in the mu and the delta opioid receptors after long-term, intermittent voluntary alcohol intake; some of these changes are in line with findings in humans. The voluntary alcohol consumption and the concomitant response to naltrexone were different for Wistar rats from different suppliers. Moreover, the Rcc Wistar rats may be more suitable for studies of alcohol use disorders due to increasing alcohol intake and the presence of a high-drinking subpopulation with increasing alcohol intake over time. The high-drinking subpopulation showed pronounced effects of naltrexone on alcohol intake.In conclusion, studies of individual differences increase understanding of variability in behavior, pharmacotherapy response and factors involved in vulnerability of alcohol use disorders.
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| 13. |
- Roman, Erika, 1974-
(författare)
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Maternal Separation in Rats : An Experimental Model for Long-Term Effects of Early Life Experiences on Neurochemistry, Voluntary Ethanol Intake and Exploration and Risk Assessment Behavior
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The period of early life is important for the development of individual brain function and behavior. Human studies have shown altered vulnerability to develop psychopathology and/or excessive drug intake, possibly leading to dependence, as a consequence of early life experiences. In the present thesis, maternal separation (MS), an experimental model for studies of early environmental influences, was used to investigate long-term effects on neurochemistry, voluntary ethanol intake and exploration and risk assessment behavior in rats. Rat pups were assigned to one of three different rearing conditions: daily 15 min (MS15) or 360 min (MS360) of MS and normal animal facility rearing (AFR) during the first three weeks of life. Measurements of adult endogenous opioid peptide levels, opioid- and dopamine receptor density revealed minor MS-induced effects on the opioid system whereas interesting alterations were found in dopamine receptor density. Long-term effects on voluntary ethanol intake showed distinct MS-induced alterations in male Wistar and ethanol-preferring AA (Alko, Alcohol) rats. Female Wistar rats were unaffected, indicating sex differences in the effects of MS on ethanol intake. Male MS15 rats generally had a slower acquisition phase and a low subsequent ethanol intake whereas male MS360 rats had a high ethanol intake. MS15 is therefore suggested to protect against a high voluntary ethanol intake in male rats whereas MS360 may serve as a risk factor. The recently established concentric square field test indicated alterations in risk assessment as well as an increased exploratory drive and somewhat higher risk-taking behavior in adult MS360 rats, while minor effects were seen in MS15 rats. Altogether, these results demonstrate that environmental influences during the period of early life can have long-term effects on neurochemistry and behavior. Of special interest is the finding that MS altered the inherited high ethanol intake in adult ethanol-preferring AA rats.
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| 14. |
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