Neuroendocrine Regulation and Effects of Stress on the Reproductive Function of Female Rats

The knowledge of the control mechanisms of fertility has implications in social (e.g., the option of conception or anti-conception in humans, populational control, and therapeutic development), economic (e.g., improvement of the fertility of domestic or captive wild species to provide food and clothing) and environmental (e.g., maintenance or reestablishment of ecosystems equilibrium, environment repopulation) aspects. Natural reproduction depends on complex interactions of hormones produced in the brain, pituitary, gonads and other organs and tissues in order to prepare the gametes and induce sexual behavior to ensure fertilization. It is well known that fertility can be markedly influenced by stress, however the interaction between the hypothalamus-pituitary-gonadal axis (HPG) and stress system (hypothalamus-pituitary-adrenal axis, sympathetic system and neurotransmitters brain systems) remains poorly understood. Gonadotropin-releasing hormone (GnRH) neurones constitute the final output pathway of the neuronal network controling gonadotropins preovulatory surges and ovulation. This neuronal network depends on direct and indirect actions of several neuromediators whose specific roles are little known, and it is also a pathway through which the stressful stimuli may interfere on gonadotropins release and ovulation. This project investigates: 1) neural circuits and neuromediators (norepinephrine, angiotensin II, neuropeptide Y, nitric oxide, leptin, serotonin, oxytocin) involved in tonic and cyclic control of gonadotropins and prolactin secretion as well as their modulation by ovarian steroids; 2) the neuroendocrine and sympathetic control of ovarian function; and 3) the effects of stressor stimuli in the neonatal period or in adulthood on the control of reproductive functions. NEUROENDOCRINE REGULATION AND EFFECTS OF STRESS ON THE REPRODUCTIVE FUNCTION OF FEMALE RATS