Nongonadal LH receptors, their involvement in female reproductive function and a new applicable approach.

Luteinising hormone (LH) and human chorionic gonadotropin (hCG) share a common receptor in gonadal cells. The receptors have also been detected in several nongonadal but reproduction-associated tissues of pigs, cattle, and other species including the uterus (myometrium, endometrium), oviduct, cervix, blood vessels, mammary gland and other tissues. The main role of LH/hCG receptors in the myometrium is stimulation of growth and hyperplasia, and relaxation of uterine motility; hCG also boosts blood flow in the uterine artery. LH and hCG can increase production of prostaglandins in the endometrium, oviduct, and blood vessels. We suggest that the preovulatory surge of LH plays an important role in controlling oviductal contractions. Awareness of LH binding to many tissues of the female reproductive tract and integration with embryonic factors may lead to the elaboration of new strategies for improved reproductive efficiency in domestic species. Mammary glands also possess LH/hCG receptors through which gonadotropins can affect the metabolism of steroid hormones and could play an inhibitory role in mammary carcinogenesis and in the growth of breast tumours. A novel approach to target and ablate carcinoma cells through LH receptors is described.