Effect of dihydrotestosterone on pituitary follicle-stimulating hormone isoforms in adult male rats treated with a gonadotropin-releasing hormone antagonist.

The effect of androgens on the oligosaccharide structure of follicle-stimulating hormone (FSH) isoforms was studied in adult male rats treated with a potent gonadotropin-releasing hormone (GnRH) antagonist. Animals were castrated (Cx), and 24 h later were treated with physiological doses of either testosterone propionate (T) or dihydrotestosterone propionate (DHT) (0.25 mg/rat in corn oil, daily, s.c.) for 7 days. The antiandrogen flutamide (F; 5 mg/day/rat, twice a day, s.c.) was administered to either Cx-T or Cx-DHT rats to block androgen action. The GnRH antagonist Org 30276 (Ant; 1 mg/kg/day, s.c.) was injected to both Cx- and Cx-DHT treated rats. FSH serum levels reached normal values in Cx rats treated with either T or DHT, whereas those treated with F retained Cx conditions. Both Cx-Ant and Cx-Ant-DHT treated animals presented normal serum FSH levels. Concanavalin A affinity chromatography was used to isolate pituitary FSH isoforms according to their carbohydrate inner structure. An increased proportion of FSH isoforms bearing complex-type oligosaccharides was observed in Cx rats treated with T or DHT, whereas the proportion of these isoforms was reduced in Cx and Cx-T-F or Cx-DHT-F rats. These results demonstrate that functional androgens are needed to complete the oligosaccharide processing of FSH. In addition, the proportion of the different pituitary FSH isoforms after DHT replacement was equivalent to that found when GnRH action was blocked, indicating that androgens are involved in the regulation of carbohydrate incorporation to the FSH molecule by acting mainly at the pituitary level, independently of GnRH action.
(Copyright 2003 S. Karger AG, Basel)