ACTION OF STEROIDS ON LH-RH PROVOKED GONADOTROPIN RELEASE

Abstract

The action of mesterolone (1 .alpha.-methyl-17 .beta.-hydroxy-5 .alpha.-androsten-3-one) mesterolone cypionate, testosterone, 17 .alpha.-methyl-testosterone, 17 .beta.-hydroxy-5 .alpha.-androstane-3-one, cyproterone acetate and D-norgestrel on basal and LH-RH [luteinizing hormone-releasing hormone] stimulated gonadotropin release was studied in vitro. Hemi-gland preparation of the [rat] anterior pituitary were incubated in the presence or absence of steroids and/or LH-RH. Steroid hormones were added to a concentration of 25, 5 and 1 .mu.g/ml medium. Basal levels of LH [luteinizing hormone] and FSH [follicle stimulating hormone] discharge were not influenced by mesterolone; inhibition of LH-RH stimulated gonadotropin release was noted at 25 .mu.g mesterolone/ml medium. Addition of mesterolone cypionate to the incubation medium did not change basal FSH levels; an inhibition of LH-RH provoked FSH discharge was noted. Basal LH release was stimulated by the presence of 1 .mu.g mesterolone cipionate/1 ml medium. LH-RH stimulated LH release in the presence of 25, 5 and 1 .mu.g mesterolone cipionate/1 ml medium was indistinguishable from control levels. Basal levels of LH and FSH were not affected by testosterone; an impaired gonadotropin response to LH-RH was observed in the presence of testosterone. At 1 .mu.g testosterone/1 ml medium only LH response to LH-RH was found. Basal gonadotropin levels in the presence of 17 .alpha.-methyl-testosterone were indistinguishable from control values. The only inhibition of LH-RH action was found for stimulation of LH release at 25 .mu.g 17 .alpha.-methyl-testosterone/ml medium. 17 .beta.-Hydroxy-5 .alpha.-androstane-3-one stimulated basal LH and FSH discharge, and LH-RH actions were not impaired. Cyproterone acetate stimulates basal pituitary gonadotropin discharge at high concentration, without blunting responses to LH-RH. No action of D-norgestrel on basal and LH-RH stimulated gonadotropin release was observed. Steroids apparently modulate LH-RH actions at the pituitary level. The fine control of gonadotropin release resides at the adenohypophysis, whereas the coarse control of LH and FSH discharge is at the hypothalamus and/or other centers of the CNS.