Effect of pre-treatment of long-term ovariectomized rats with anti-LRH on the response of the pituitary gland in vitro to the analogue of LRH D-ser-(tBu)6-des-gly10-ethylamide-LRH (Buserelin).

Ovariectomized rats were injected iv with an antiserum against LRH or normal rabbit serum. Anti-LRH caused a decrease of plasma LH and FSH. After 24 or 48 h, the rats were decapitated and the pituitary glands incubated in the presence of an analogue of LRH which reacts minimally with anti-LRH (Buserelin). Pre-treatment with anti-LRH caused an increased response of pituitary LH release to Buserelin. Similar results were obtained with regard to FSH. In this case, however, basal release of FSH was lowered by pre-treatment with anti-LRH. Pituitary LH and FSH contents were not affected by anti-LRH, but synthesis of LH and FSH in vitro was smaller than in control glands obtained from rats pre-treated with normal rabbit serum.