GnRH secretion - Ochotona princeps (American pika)

Hypothalamic gonadotropin-releasing hormone (GnRH) neurons are key regulators of reproduction. They release GnRH into the portal circulation. In turn, GnRH stimulates the pituitary gland to secrete follicle-stimulating hormone and luteinizing hormone (LH) to regulate gonadal functions. Gonadal steroids provide feedback to regulate GnRH release. GnRH neurons express the kisspeptin receptor, GPR 54, and kisspeptins potently stimulate the release of GnRH by depolarising and inducing sustained action potential firing in GnRH neurons. It is also demonstrated that Kisspeptin-GPR54 system positively regulates the GnRH expression with a time course consistent with activation of Akt and MAP kinase signaling pathways.