Androgens positively regulate follicle-stimulating hormone β-subunit mRNA levels in rat pituitary cells

Abstract

We have shown previously that androgens negatively regulate LH α and β-subunit mRNA levels, but have little or no effect on FSHβ mRNA levels in rats in vivo. In contrast, estrogen negatively regulates all three gonadotropin subunit mRNA levels in vivo. We have examined the effects of these sex steroids on gonadotropin subunit synthesis directly at the level of the pituitary gland by using cultured rat pituitary cells. Adult female and male rat pituitaries were dissected, dispersed enzymatically, and maintained in culture for 2 days. At that time, cells were treated for varying lengths of time with either medium alone or sex-steroid hormone treatments (estradiol or testosterone). Dose-response and time-course experiments were performed. Cells were then harvested and total RNA was extracted. Gonadotropin subunit mRNA levels were assessed by blot hybridization techniques. Sex-steroid hormones were added to achieve final concentrations ranging from 10-12 to 10-6 M for dose response experiments and 10-8 M for time-course experiments. Testosterone treatment (10-8 M) increased FSHβ mRNA levels 3-fold in females (P < 0.01) and males (P < 0.05), but had no effect on α or LHβ mRNA levels in either sex. Dose-related increases in FSHβ mRNA levels with increasing concentrations of testosterone were observed in both female and male pituitary cell cultures. Time-course studies revealed that the testosterone-stimulated increases in FSHβ mRNA levels are statistically significant by 12 h and 6 h after hormone addition in female and male cultures, respectively. We conclude that, in rats, 1) androgens positively regulate FSHβ mRNA levels but have no effects on α or LHβ mRNA levels, and that these effects can be observed directly at the level of the pituitary cell, and 2) estradiol does not have any direct effect on steady-state gonadotropin subunit mRNA levels in this system. Copyright © 1990 by The Endocrine Society.