Effects of Early Maternal Separation on Subsequent Reproductive and Behavioral Outcomes in Male Rats

Abstract

To investigate effects of maternal separation on reproductive and behavioral outcomes, male Wistar rats were separated from their mothers daily for 3 hr (maternal separation; MS) or 0 hr (control) from postnatal day (PND) 1 to 14. Timing of puberty, reproductive parameters, hormone levels, and aggressive behaviors in juvenile and adult rats were examined. Contrary to expectations, there was no effect of maternal separation on any measure of aggression. However, maternal separation altered peripubertal testosterone secretion and increased mean day of preputial separation. In addition, adult MS males demonstrated less total sexual behavior. There was no difference in sperm counts or testosterone levels at necropsy on PND 56 or in adulthood, but seminal vesicle weights were increased in adult MS rats. These results suggest that early life stress may influence hypothalamic-pituitary-gonadal axis development in males, at least during peripuberty.

Cognitive impairment effects of early life stress in adolescents can be predicted with early biomarkers: Impacts of sex, experience, and cytokines

“…During puberty, testosterone has been shown to promote IL-10 expression in males (Zhang et al, 2007); therefore the observed drop in IL-10 in MS males during puberty suggests that the reduced testosterone reported here, and observed by others (Bodensteiner et al, 2014), in adolescent MS males could have a modulatory role of IL-10 levels in these rats. Notably, we did not observe an effect of MS on the timing of puberty in males as measured by balano-preputial separation; therefore it does not appear that decreased testosterone levels affected the timing of pubertal development.…”

“…Since MS has not been shown to affect baseline estradiol levels in female rats but can alter peripubertal testosterone secretion (Bodensteiner et al, 2014), we also assessed plasma testosterone concentrations from blood samples at P35 using ELISA (R&D, Minneapolis, US). The mean minimum detectable dose was 0.030 ng/mL.…”

Early‐life stress increases the survival of midbrain neurons during postnatal development and enhances reward‐related and anxiolytic‐like behaviors in a sex‐dependent fashion

“…Additionally, Bodensteiner et al (2014) have recently shown that MS males displayed a delay in puberty and decreased testosterone levels on PND 42. As adults, MS males have been shown to display a lower number of sexual behaviors, despite the observation of similar levels of testosterone in MS and control rats (Bodensteiner et al, 2014). Therefore, we cannot rule out the possibility that MS‐induced changes in peri‐ or postpubertal levels of sex hormones are also responsible for the sex‐related differences in our study.…”

Effects of early adolescent environmental enrichment on cognitive dysfunction, prefrontal cortex development, and inflammatory cytokines after early life stress

“…However, during puberty testosterone has been shown to promote an anti‐inflammatory profile in males (Zhang, Xing, He, & Wang, ); therefore, the observed pro‐inflammatory profile in MS‐exposed adolescent males suggests that testosterone modulation of cytokines may be diminished in these rats. Indeed, adolescent male rats exposed to MS have been shown to display reduced testosterone levels (Bodensteiner, Christianson, Siltumens, & Krzykowski, ). Although we did not assess gonadal hormones in the present study, the differential influence of hypothalamic–pituitary–gonadal axis development on immune function in males and females may contribute to sex‐dependent effects of MS and requires further study.…”