Androgens promote insulin-like growth factor-I and insulin-like growth factor-I receptor gene expression in the primate ovary

Abstract

It has recently been shown that androgens increase the growth of immature follicles in the primate ovary. In the present study the effect of androgens on ovarian insulin-like growth factor I (IGF-I) and IGF-I receptor gene expression was investigated. The study groups included five follicular phase, placebo-treated controls, and four testosterone- and three dihydrotestosterone (DHT)-treated rhesus monkeys. The treatment period was 5 days. Both testosterone and DHT treatment resulted in significant, 3-4-fold increases in IGF-I mRNA concentration in granulosa, thecal and interstitial compartments. Likewise, both androgens induced significant increases in the amount of IGF-I receptor mRNA, most notably in thecal cells and less markedly in granulosa and interstitium (P < 0.05). These changes in amounts of IGF system mRNA were documented in growing follicles up to the small antral (</=1 mm diameter) stage. Larger follicles were too few in number for significant comparisons. By contrast, amounts of ovarian insulin receptor mRNA were not appreciably altered by androgen treatment. These data suggest that IGF-I and its cognate receptor may mediate androgen-induced ovarian follicular and thecal-interstitial growth.