A Model of LHRH “Self-Priming” at the Pituitary

Abstract

Luteinising hormone (LH) is secreted from specialised cells (gonadotrophs) in the anterior pituitary gland, and regulates ovarian follicular development and ovulation. The secretory pattern of LH changes throughout the reproductive cycle (the menstrual cycle in women, the oestrous cycle in other female mammals). In all female mammals, a large preovulatory surge in the release of LH is the main trigger for ovulation to occur; at other times LH is released into the systemic circulation in small intermittent pulses, the frequency and amplitude of which are critical for follicular development. LH is packaged into large secretory granules within the gonadotrophs, and these granules are released from the pituitary gland in response to the secretion of LH-releasing hormone (LHRH) from neurones in the hypothalamus. As a consequence of electrical activation of LHRH neurones, LHRH is released into blood vessels which link the hypothalamus and pituitary.