| 1. |
- 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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| 2. |
- Wallén-Mackenzie, Åsa, et al.
(författare)
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Restricted cortical and amygdaloid removal of vesicular glutamate transporter 2 in preadolescent mice impacts dopaminergic activity and neuronal circuitry of higher brain function.
- 2009
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Ingår i: The Journal of neuroscience : the official journal of the Society for Neuroscience. - 1529-2401 .- 0270-6474. ; 29:7, s. 2238-51
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Tidskriftsartikel (refereegranskat)abstract
- A major challenge in neuroscience is to resolve the connection between gene functionality, neuronal circuits, and behavior. Most, if not all, neuronal circuits of the adult brain contain a glutamatergic component, the nature of which has been difficult to assess because of the vast cellular abundance of glutamate. In this study, we wanted to determine the role of a restricted subpopulation of glutamatergic neurons within the forebrain, the Vglut2-expressing neurons, in neuronal circuitry of higher brain function. Vglut2 expression was selectively deleted in the cortex, hippocampus, and amygdala of preadolescent mice, which resulted in increased locomotor activity, altered social dominance and risk assessment, decreased sensorimotor gating, and impaired long-term spatial memory. Presynaptic VGLUT2-positive terminals were lost in the cortex, striatum, nucleus accumbens, and hippocampus, and a downstream effect on dopamine binding site availability in the striatum was evident. A connection between the induced late-onset, chronic reduction of glutamatergic neurotransmission and dopamine signaling within the circuitry was further substantiated by a partial attenuation of the deficits in sensorimotor gating by the dopamine-stabilizing antipsychotic drug aripiprazole and an increased sensitivity to amphetamine. Somewhat surprisingly, given the restricted expression of Vglut2 in regions responsible for higher brain function, our analyses show that VGLUT2-mediated neurotransmission is required for certain aspects of cognitive, emotional, and social behavior. The present study provides support for the existence of a neurocircuitry that connects changes in VGLUT2-mediated neurotransmission to alterations in the dopaminergic system with schizophrenia-like behavioral deficits as a major outcome.
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| 3. |
- Lindberg, Frida A, et al.
(författare)
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Behavioral profiling of SLC38A10 knockout mice using the multivariate concentric square field™ test
- 2022
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Ingår i: Frontiers in Behavioral Neuroscience. - : Frontiers Media S.A.. - 1662-5153 .- 1662-5153. ; 16
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: SLC38A10 is a gene that encodes the SLC38A10 protein, also known as SNAT10. The SLC38 family is evolutionary old, and SLC38A10 is one of the oldest members of the family. It is ubiquitously expressed, and its substrates are glutamine, glutamate, alanine, aspartate, and serine. However, little is known about its biological importance.Methods: In the current study, an SLC38A10 knockout mouse was run in the multivariate concentric square field (TM) (MCSF) test. The MCSF test gives the mouse a choice of areas to explore; sheltered areas, elevated and illuminated areas, or open spaces, and a behavioral profile is obtained. The multivariate data obtained were analyzed (i) for each parameter, (ii) parameters grouped into functional categories, and (iii) with a principal component analysis.Results: In the trend analysis, knockout mice had a decreased exploratory behavior compared to controls but did not show a distinct grouping in the principal component analysis.Discussion: There was not a pronounced difference in the behavioral profile in SLC38A10 knockout mice compared to their wild-type controls, although subtle alterations in zones associated with exploratory behavior and risk assessment in female and male knockout mice, respectively, could be observed. These results imply that a loss of function of the SLC38A10 protein in mice does not drastically alter behavior in the MSCF test.
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| 4. |
- 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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| 5. |
- Roman, Erika, et al.
(författare)
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Short and prolonged periods of maternal separation and voluntary ethanol intake in male and female ethanol-preferring AA and ethanol-avoiding ANA rats
- 2005
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Ingår i: Alcoholism. - 0145-6008 .- 1530-0277. ; 29:4, s. 591-601
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Genetic as well as environmental factors can affect the propensity for psychopathology and/or drug dependence. Maternal separation represents an animal experimental model that is useful in studies of effects of early life experiences. The authors have established a protocol for short and prolonged periods of maternal separation to study adult neurochemistry, behavior, and ethanol intake and have previously reported alterations in ethanol intake in Wistar rats and ethanol-preferring rats. The aim of the current study was to more thoroughly study how early life experiences affect an inherited propensity for high and low ethanol intake, respectively, in male and female ethanol-preferring AA (Alko alcohol) and ethanol-avoiding ANA (Alko, Non-Alcohol) rats. METHODS: AA and ANA pups were assigned to one of three different rearing conditions: 15 min (MS15) or 360 min (MS360) of daily maternal separation in litters or normal animal facility rearing (AFR) during postnatal days 1 to 21. In adulthood, voluntary ethanol intake was investigated using the two-bottle free choice paradigm. RESULTS: In male ethanol-preferring AA rats, MS15 resulted in a lower intake and fewer high-preferring animals at 8% and 10% ethanol compared with MS360 rats. The male MS360 rats had a higher ethanol intake at 8% and 10% ethanol in comparison with AFR rats. In contrast, the female AA MS15 and MS360 rats had a lower ethanol intake and a lower preference for the 10% ethanol solution compared with the female AA AFR rats. In male and female ANA rats, no major separation-induced effects were found. CONCLUSIONS: The current results show that genetic inheritance can be affected by environmental manipulations in AA rats with an inherent high ethanol intake. The findings in female ethanol-preferring AA rats give further evidence of a differential outcome of maternal separation in male and female rats, as previously shown.
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| 6. |
- Lundberg, Stina, 1990-, et al.
(författare)
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Behavioral profiling in early adolescence and early adulthood of male Wistar rats after short and prolonged maternal separation
- 2020
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Ingår i: Frontiers in Behavioral Neuroscience. - : Frontiers Media SA. - 1662-5153 .- 1662-5153. ; 14
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Tidskriftsartikel (refereegranskat)abstract
- Early-life stress and its possible correlations to genes, environment, and later health outcomes can only be studied retrospectively in humans. Animal models enable the exploration of such connections with prospective, well-controlled study designs. However, with the recent awareness of replicability issues in preclinical research, the reproducibility of results from animal models has been highlighted. The present study aims to reproduce the behavioral effects of maternal separation (MS) previously observed in the multivariate concentric square fieldTM (MCSF) test. A second objective was to replicate the adolescent behavioral profiles previously described in the MCSF test. Male rats, subjected to short or prolonged MS or standard rearing, were subjected to behavioral testing in early adolescence and early adulthood. As seen in previous studies, the behavioral effects of MS in the MCSF were small at both tested time points. When tested in early adolescence, the animals exhibited a similar behavioral profile as previously seen, and the finding of adolescent behavioral types was also reproduced. The distribution of animals into the behavioral types was different than in the initial study, but in a manner consistent with developmental theories, as the current cohort was younger than the previous. Notably, the Shelter seeker behavioral type persisted through development, while the Explorer type did not. The lack of basal behavioral effect after MS is in line with the literature on this MS paradigm; the working hypothesis is that the prolonged MS gives rise to a phenotype predisposed to negative health outcomes but which is not apparent without additional provocation.
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| 7. |
- 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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| 8. |
- 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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| 9. |
- 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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| 10. |
- Palm, Sara, et al.
(författare)
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Effects of Rearing Conditions on Behaviour and Endogenous Opioids in Rats with Alcohol Access during Adolescence
- 2013
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:10, s. e76591-
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Tidskriftsartikel (refereegranskat)abstract
- Abstract: Causal links between early-life stress, genes and later psychiatric diagnoses are not possible to fully address in human studies. Animal models therefore provide an important complement in which conditions can be well controlled and are here used to study and distinguish effects of early-life stress and alcohol exposure. The objective of this study was to investigate the impact of rearing conditions on behaviour in young rats and if these changes could be followed over time and to examine interaction effects between early-life environment and adolescent alcohol drinking on behaviour and immunoreactive levels of the opioid peptides dynorphin B, met-enkephalin-Arg(6)Phe(7) and beta-endorphin. We employed a rodent model, maternal separation, to study the impact of rearing conditions on behaviour, voluntary alcohol consumption and alcohol-induced effects. The consequences of short, 15 min (MS 15), and long, 360 min (MS 360), maternal separation in combination with adolescent voluntary alcohol consumption on behaviour and peptides were examined. A difference in the development of risk taking behaviour was found between the MS15 and MS360 while the development of general activity was found to differ between intake groups. Beta-endorphin levels in the pituitary and the periaqueductal gray area was found to be higher in the MS15 than the MS360. Adolescent drinking resulted in higher dynorphin B levels in the hippocampus and higher met-enkephalin-Arg(6)Phe(7) levels in the amygdala. Amygdala and hippocampus are involved in addiction processes and changes in these brain areas after adolescent alcohol drinking may have consequences for cognitive function and drug consumption behaviour in adulthood. The study shows that individual behavioural profiling over time in combination with neurobiological investigations provides means for studies of causality between early-life stress, behaviour and vulnerability to psychiatric disorders.
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