Follicle-Stimulating Hormone Stimulates Ovarian Synthesis of Proteoglycans in the Estrogen-Stimulated Hypophysectomized Immature Female Rat*

Abstract

FSH [follicle stimulating hormone] stimulates antrum formation, but the mechanisms involved have remained obscure. Because antral fluid contains proteoglycans, the incorporation of 35SO4 into ovarian proteoglycans was studied in estrogen-primed hypophysectomized immature female rats [HIFR] in which antrum formation was stimulated by administration of ovine FSH, highly purified human FSH and/or hCG [human chorionic gonadotropin]. Two days after hypophysectomy and insertion of a silastic capsule containing diethylstilbestrol [DES], graded doses of ovine FSH (NIH S-11) were injected s.c. twice daily for 4 days. On day 4, 35SO4 (200-300 .mu.Ci) was given i.p. and the animals were sacrificed 24 h later. The ovaries were homogenized, the 100,000 .times. g supernatants filtered through 0.025 .mu.M Millipore filters and the non-filterable radioactivity determined. The non-filterable radioactivity was macromolecular proteoglycans, because incubation with chondroitinases AC or ABC (with or without papain pretreatment) resulted in a 75% decrease in non-filterable radioactivity, and the degradation products were principally derived from chondroitin-4-SO4 (63-92%) and chondroitin-6-SO4. Sulfate incorporation into ovarian proteoglycans was linearly related to the log dose of FSH over the range 100-1200 .mu.g FSH, with a maximal response of 18.5-fold. This biochemical change was accompanied by increased Alcian blue staining of follicular proteoglycans as seen by light microscopy. The response to FSH could be augmented by coadministration of hCG. hCG alone, in 100-fold higher doses, resulted in a similar parallel response in 35SO4 uptake. In vitro exposure to FSH stimulated a statistically significant increase of 35SO4 incorporation into a macromolecular fraction of granulosa cells in short term tissue culture. FSH stimulates a dose-dependent incorporation of radioactive sulfate into ovarian proteoglycans in the DES-primed HIFR.