This is a R21 grant to determine if a slight elevation in circulating androgen levels during pubertal development, reminiscent of that observed in adolescent girls predisposed to polycystic ovarian syndrome (PCOS), leads to pathological characteristics of this disease in a primate model. The grant builds on promising preliminary data collected in a group of female rhesus monkeys who were treated with testosterone (T) for the past 3 years and are showing some neuroendocrine changes characteristic of PCOS. This grant would allow us to continue to study these valuable female monkeys for the next two years to determine if they develop additional symptomology associated with PCOS as they enter young adulthood. Development of this novel primate model of PCOS would be useful not only in improving our understanding of the etiology of PCOS but also in future studies to test new clinical treatments for PCOS. PCOS is a common disorder, occurring in 6-8% of premenopausal women and representing the most common cause of anovulatory infertility. Clinical symptoms include hirsutism, hyperandrogenism, menstrual irregularity, polycystic ovaries, an increased ratio of LH/FSH, increased pulsatile LH secretion, increased pituitary responsiveness to GnRH, and decreased sensitivity to progesterone negative feedback. There is an increased incidence of obesity, particularly abdominal obesity, as well as insulin insensitivity in PCOS, but not all individuals with PCOS have these metabolic symptoms. The causal mechanism(s) underlying the initiation of PCOS are not known, but there is growing evidence that hyperandrogenism represents a final common pathway for the development of PCOS. We have found that female monkeys exposed to mild hyperandrogenism during pubertal development, via sc T-filled silastic implants, now have increased pulsatile LH secretion and increased responsiveness to GnRH compared to control animals receiving cholesterol-filled implants. In the proposed project we will (1) determine the continued effect of a slight elevation in circulating androgen over pubertal development on (a) the central neural drive to the reproductive axis (by measuring pulsatile LH secretion, responsiveness to GnRH, and sensitivity to progesterone negative feedback), (b) ovarian follicular development and the presence of cystic follicles, (c) hormonal concomitants of PCOS (including decreased insulin sensitivity, increased antimullerian hormone) and (d) body fat distribution;(2) determine if the effects of pubertal androgen exposure can be reversed by decreasing circulating androgen levels in early adulthood, and (3) determine if a typical Western diet (with 30% of calories from fat) augments the development/severity of PCOS symptoms.
This project builds on promising preliminary data collected in a group of female rhesus monkeys showing that a slight elevation in circulating testosterone levels during puberty leads to neuroendocrine symptoms characteristic of polycystic ovarian syndrome. This project will examine further the neuroendocrine, ovarian and metabolic changes following androgen exposure to validate this primate model for studies on the etiology and treatment of PCOS.
