Antidepressants blunt the effects of inescapable stress on male mating behaviour and decrease corticotropin-releasing hormone mRNA expression in the hypothalamic paraventricular nucleus of the Syrian hamster (Mesocricetus auratus).

Abstract

Stress decreases sexual activity. However, emerging research suggests that the psychological aspect of control prevents the detrimental effects of stress on male mating behaviour. The present study examined the effects of chronic escapable/inescapable stress on mating behaviour in the male Syrian hamster. Additionally, the ability of the antidepressant clomipramine to prevent the adverse effects of stress on mating behaviour was explored. In this paradigm, two groups received the same electric footshock stress, but differed in the psychological aspect of control. Cohorts were divided into two groups. One group received clomipramine via a sugar water solution while the other received plain sugar water. Mating behaviour was quantified before and after 12 consecutive days of stress. The morning following the final stress and behaviour session, trunk blood and brains were collected to assess: (i) plasma concentrations of testosterone and glucocorticoids and (ii) corticotropin-releasing hormone (CRH) mRNA expression within the paraventricular nucleus of the hypothalamus (PVN). In the drug-free groups, several aspects of mating behaviour were disrupted by inescapable but not escapable stress, including anogenital investigation before the first ejaculation and time of first ejaculation. Additionally, both escapable and inescapable stress caused a decrease in total hit rate compared to the no-stress control group. Unlike the sugar-water treated animals, hamsters in either stress condition receiving clomipramine showed no differences in anogenital investigation, time of first ejaculation, hit rate, or any other aspect of mating behaviour measured, compared to the clomipramine no-stress control males. The stress-induced inhibition of mating behaviour could not be explained by changes in baseline plasma concentrations of testosterone or total glucocorticoids; these values did not vary between any of the six treatment groups. It was found that clomipramine lowers CRH mRNA expression in the PVN by 74%, regardless of stressor conditions. The results of the present study have broad implications for understanding the relationships between stress, depression and reproduction, and for the treatment of people and animals suffering from the adverse effects of stress.