Role of Serotonin in Mediating Stress-Induced Infertility

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DESCRIPTION (provided by applicant): The overall goal of this grant is to continue our studies to determine the mechanisms by which common life stresses (i.e., dieting, moderate exercise and psychological stress) impair activity of the reproductive axis and fertility. Female cynomolgus monkeys, which like women have 28-day menstrual cycles throughout the year, show individual differences in responsiveness to stress, with stress-sensitive animals rapidly developing stress-induced reproductive dysfunction, and stress-resilient animals maintaining normal menstrual cyclicity throughout stress exposure. The stress used for these studies is patterned after that documented in women with Functional Hypothalamic Amenorrhea (FHA; a clinical condition which accounts for as much as 30% of female infertility) in which monkeys are exposed to a mild psychological stress (moving to a new room) and a moderate metabolic stress (a 20% decrease in calorie intake and moderate running for an hour a day, 5 days a week). To date, we have studied monkeys in non-stressed conditions. We have found that stress-sensitive monkeys have lower physiological release of serotonin, a down regulation of function in the central serotonergic system [as indicated by lower tryptophan hydroxylase (THP) 2 gene expression, less serotonin transporter (SERT) gene expression, less 5HT-1A receptor gene expression, and less expression of genes degrading serotonin (MAO-A and MAO-B)], as well as an up-regulation of 5HT2A and 2C receptors in the hypothalamus, compared to more stress-resilient animals. We have preliminary data showing that treatment of stress-sensitive monkeys in a nonstressed condition with a serotonin reuptake inhibitor (SSRI) increases reproductive hormone secretion in a normal menstrual cycle. In this grant application we will test whether SSRI treatment can prevent stress-induced suppression of the reproductive axis and thus may be a novel therapy for treatment of stress-induced infertility. We will examine changes in central neural systems that occur with SSRI therapy. We will also run a small pilot clinical study to determine if SSRI therapy in women with FHA is able to increase reproductive hormone secretion. This collaboration between Drs. Cameron, Bethea and Berga represents an unique opportunity to test this potential new therapy for FHA both in an appropriate animal model in which we can examine neural systems, and in a small pilot clinical study.