Regulation of LH beta subunit mRNA in the sheep pituitary gland during different feedback states of estradiol

Abstract

The feedback effects of gonadal steroids on the amounts of in vitro translated luteinizing hormone (LH) beta subunit were examined using cell-free assays. These amounts were then correlated with serum and pituitary concentrations during various feedback states. RNA was prepared, translated and products identified by immunoprecipitation and gel electrophoresis. The amounts of beta subunit varied in a pattern similar to that observed for alpha subunit. In ovariectomized ewes, the amounts of beta were 2–3X those seen in negative feedback groups and slightly more than those seen in animals exhibiting an LH surge. The pituitary LH concentration in ovariectomized ewes was also higher than those seen in the other groups, however, the serum concentrations in the positive feedback group were the highest of all groups. These results provide evidence for: 1) a separate, but coordinate, control of gonadotropin subunit synthesis; and 2) a contribution of subunit synthesis to the effects of positive and negative steroid feedback on pituitary LH amounts.