Differential Control of Luteinizing Hormone and Follicle-Stimulating Hormone Secretion by Androgens in Rat Pituitary Cells in Culture: Functional Diversity of Subpopulations Separated by Unit Gravity Sedimentation*

Abstract

Monolayer cultures of dispersed pituitary cells derived from 14-day-old female rats were treated for 70 h with nanomolar concentrations of testosterone (T) or 5.alpha.-dihydrotestosterone (DHT), and the effect of these hormones on LHRH[luliberin]-stimulated FSH [follicle stimulating hormone, follitropin] and LH [luteinizing hormone, lutropin] release was tested. The effect of androgen treatment on FSH release depended critically on the concentration of LHRH; FSH release either was slightly stimulated, markedly depressed or not affected at all. In contrast, LH release was profoundly inhibited except at very high concentrations of LHRH. Various cell populations, separated according to size and density by gradient sedimentation at unit gravity, did not respond equally to DHT treatment. Inhibition of FSH release did not occur in all gonadotrophs and was seen only at critical LHRH concentrations. Stimulation of FSH release, observed at low LHRH concentrations, was found only in the fraction with the largest gonadotrophs; in the latter there was no concomitant change in LH release. FSH release from small gonadotrophs remained unchanged, but LH release was depressed. Apparently, LHRH can provoke selective FSH release without any change in LH release, and LH secretion can be inhibited without a concomitant fall in FSH. Such independent control may be mediated through separate subpopulations of functionally diverse gonadotrophs.