Thesis, COLLÉGIALITÉ

Abstract

Chronic stress is an increasing cause for concern in modern society. Stress is an evolutionary mechanism allowing adaptation to urgent situations. However, in western lifestyle, stress has become a burden, which is often associated to disease, including mental and behavioral disruption. Additionally, stress seems having a wide range of effects that could impact the offspring as well. For instance, impaired reproduction and sexual behavior have been reported to be the possible result of exposure to prenatal stress. Based on this, we aimed to investigate the permanent effects of prenatal stress on female and male offspring’s sexual behavior. To induce prenatal stress, pregnant dams were submitted to restrain stress from the second to delivery day. Thereafter, pups were not undisturbed until they reached adulthood (8 weeks) where they were finally tested. Mice were put through elevated plus maze test and blood sampling, to assess for the behavioral and physiological manifestations of stress. Blood samples were collected in two conditions, home cage and 30 min following the EPM test to evaluate the functioning of the HPA axis with assessment of corticosterone and DHEA. Vaginal smear assay was performed on female to investigate their estrous cycling. Sexual performance was tested on both virgin females and males, then partner preference test was performed on both sexes to assess for the sexual preference. Our results show that anxiety and the level of stress hormones were not particularly altered in prenatally stressed females, while the males seemed to have developed resistance and reduced reactivity to stress. In fact, we observed low corticosterone response upon exposure to EPM test and low basal DHEA levels. Regarding sexual behavior, prenatally stressed females and males demonstrated similar sexual performance compared to control groups. Also, we noted that prenatal stress significantly impacted sexual preference in both female and male. These observations not only show that prenatal stress impacted male and female offspring but also that some effects were sexually dimorphic. In conclusion, prenatal stress is an increasingly wording issue that has generational repercussions. In our study we chose to evaluate the impact of prenatal stress in female and male offspring. While anxious behavior and sexual performance were affected only in males, sexual preference seemed altered in both sexes.