Gonadotropin-releasing hormone (GnRH) was first isolated, characterized, and synthesized by Schally and Guillemin in 1971. 1, 2, 3 However, it was the classic work by Knobil and co-workers demonstrating (1) that the pulsatile secretion of GnRH by the hypothalamus is the primary process controlling the menstrual cycle, 4 and (2) that tonic GnRH stimulation causes downregulation of the pituitary ....