Efeito da dexametasona no comportamento sexual de ratos machos

Abstract

The study of sexual behavior in male rats involves the analysis of motivation and sexual performance. The distinction between them is seeking sexual contact and be able to perform the copulatory act. This behavior is required for preservation of the species and not to survival of the individual, as abstinence has not, the short-term adverse effects for the organism. Thus, it differs considerably from other spontaneous behaviors such as feeding, hydration, thermoregulation or respiration. Studies show that stress and consequent activation of the hypothalamic-pituitaryadrenal (HPA) and secretion of glucocorticoids can alter various hormonal and behavioral parameters. The aim of this study was to analyze the motivation and sexual performance of male rats and its possible changes in the face of acute and chronic administration of dexamethasone (DEXA), a synthetic glucocorticoid. We used Wistar rats, kept in groups with up to four animals per cage in light-dark cycle of 12h at 21 ± 1 ° C. For analyzes of sexual performance, sexually experienced adult male rats treated with vehicle or DEXA, acute and chronic, were exposed to receptive females, recording 40 minutes. The results of behavioral analysis and immunohistochemistry for c-Fos showed that acute administration improved parameters of sexual behavior and decreased the c-Fos neurons in BST, the MnPO d in MnPOv, PVN and SON. Moreover, the chronic administration did not affect any of the parameters of performance and increased the number of positive cells in the SON c-Fos. For assessment of sexual motivation, male rats, sexually inexperienced, treated with vehicle or DEXA, were placed in an apparatus where there was a receptive female (sexual incentives) and a sexually experienced male (social incentive), recording 20 minutes, treated treated with vehicle or DEXA. The results showed that the acute administration of dexamethasone increased sexual motivation, while the chronic administration did not modify this behavior. Together, these results suggest that acute administration of dexamethasone increased sexual motivation in male rats by inexperienced sexually mechanisms involved in suppression of the HPA axis. Furthermore, acute administration of DEXA improved sexual performance parameters by decreased neuronal activity in hypothalamic areas related to the neuroendocrine control of sexually experienced male rats.