Adolescence has been described as an important period to acquire social competences required for adult life. It has been suggested that early stress experiences could affect the development of the brain at different levels. These changes in the brain during adolescence may be related with the development of psychopathologies such as depression and social anxiety in adulthood. In the first experiment, we examined long-term effects of repeated social stress during adolescence on adult social approach-avoidance behavior. For that purpose, adolescent male Wistar rats were exposed twice at postnatal day (Pnd) 45 and Pnd48 to the resident-intruder paradigm followed by three times psychosocial threat with the same resident. Three weeks after the last psychosocial threat experience the animals were behaviorally tested in a social approach-avoidance test. Socially stressed animals spent less time in the interaction zone with an unfamiliar male adult rat. These data suggest that animals exposed to social stress during adolescence show a higher level of social anxiety in adulthood. In the second experiment, we investigated whether these long-term effects of social stress during adolescence on behavior draw a parallel with changes in brain monoamine content, biosynthesis and turnover. Using the same experimental design as in the first experiment, HPLC analysis of various brain regions showed that there were no differences in monoamine content, monoamine biosynthesis and monoamines activity in the prefrontal cortex, hippocampus, hypothalamus and striatum in adulthood. These results indicate that long-lasting changes in social behavior following social stress during adolescence are not accompanied by changes in brain monoamine content, biosynthesis and turnover.
In the present research the role of gender in MDMA-induced hyperthermia and serotonin depletion is studied by injecting male and female male rats with MDMA or saline 3 times (i.p.) with 3h interval at dosages of 0.3, 1, 3 or 9 mg/kg at an ambient temperature of 25°C. The acute hyperthermia following the higher dosages was much stronger in males than in females. After the highest dose, body temperature was even raised for several days. This effect was particularly present in males where nocturnal hyperthermia persisted the whole 4-week period of sampling. Despite the differences in the acute hyperthermic response, no significant gender differences were found in 5-HT depletion 4 weeks after MDMA (9 mg/kg) administration. A striking difference was present, however, in the concentration of the 5-HT metabolite 5-HIAA after MDMA administration. In males 5-HIAA levels decreased, whereas in females this metabolite was hardly affected, suggesting a lasting increase in 5-HT turnover in females following drug administration. When genders were matched for their acute physiological hyperthermic response by repeated injection of 9 mg/kg in female rats and 6 mg/kg in male rats, 5-HT depletion was only present in females. In this experiment with matched acute physiological responses 5-HIAA levels also decreased much stronger in males, suggesting an increased 5-HT turnover in females 4 weeks after MDMA administration. In conclusion, although male rats are clearly more susceptible for the acute as well as the lasting hyperthermic effects of MDMA than females, this is not reflected in levels of 5-HT depletion following administration of similar dosages of the drug. This may indicate that, in case of a similar thermogenic response, females have a higher 5-HT neurotoxicity following MDMA than males.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.