Role of endogenous primate LH in maintaining corpus luteum function of the monkey

Abstract

Antiserum to human chorionic gonadotropin (Ayerst) was prepared by administering it in Freund's complete adjuvant to rabbits. Contaminating non-specific antibodies were absorbed with dilute normal human serum and a kaolin-acetone extract prepared from urine of children. Cross-reactivity of this material with human LH or monkey pituitary extract was established using the Ouchterlony double diffusion and competitive binding test. Biological testing involved the capacity of this material to neutralize the ovulation inducing activity of human LH and monkey pituitary extract. It was also able to compete with these two preparations in a modified radioimmunoassay using ¹²⁵I-labeled human LH. This LH specific antibody (CG A/S) was then injected (2 ml/day) on days 15 through 18 or 15 and 16 into normally cycling Macaca jascicularis. Blood samples were drawn on alternate days beginning on day 9 during the experiment and the serum assayed for progesterone. Progesterone values increased due to ovulation and were subsequently reduced by the injected CG A/S. Those animals receiving only 2 injections had progesterone levels which rebounded to normal levels upon withdrawal of injections. However, 4 injections prevented this rebound and animals so treated had menstrual cycles reduced by 5 to 9 days. The conclusion drawn from these observations is that LH has an important role in the maintenance of the continued function of the subhuman primate corpus luteum.