Pituitary concentration of luteinizing hormone in three types of "constant estrous" rats.

Abstract

compare the mechanisms involved in the production of persistent vaginal cornification, pituitary concentrations of LH were measured in rats made “persistent estrus” with hypothalamic lesions, testosterone injection at 5 days of age, or exposure to constant light. Pituitary LH was measured in pooled saline extracts, using the ovarian ascorbic acid depletion method, in all groups following 35–40 days of vaginal cornification and also after 10–13 days of cornification in constant light-and testosterone-treated rats. Pituitaries collected from normal animals during each of the days of the estrous cycle were used for reference; since testosterone-treated rats were younger than the other experimental groups at autopsy, glands from normal estrous litter mates were used for comparison. In normals, LH concentration was 2.45 μg/rag at proestrus and 1.19 μg/mg at estrus. Progressive increases in LH were found during the 3 days of diestrus. While glands from rats with constant light- and testosterone-induced “persist...