Gonadotropin-releasing hormone (GnRH) is a decapeptide that is synthesized and released from specific neurons in the hypothalamus. It is responsible for the pituitary expression of the gonadotropins, luteinizing hormone, and follicle-stimulating hormone. In turn, these gonadotropins 1) signal the gonads to synthesize and release estrogen or testosterone and 2) stimulate gametogenesis. Complex feedback mechanisms operate at the level of the hypothalamus and pituitary. The molecular mechanisms that translate environmental and metabolic cues into changes in GnRH expression are beginning to be elucidated. Many studies have contributed to our understanding of the control mechanisms for the expression of hypothalamic GnRH. The advent of transformed cultured GnRH-expressing cell lines has certainly spirited the field forward, and the ability to use molecular techniques to study GnRH gene expression in vivo has further advanced the field. Studies in infertile patients have identified genes that may be important in GnRH gene expression and that, therefore, may play an etiologic role in hypothalamic hypogonadism.
Section on Reproductive Endocrinology, Division of Endocrinology, Children’s Hospital, Boston, MA, USA .
Correspondence to Sally Radovick, MD, Division of Endocrinology, Children's Hospital, Enders 4, 300 Longwood Avenue, Boston, MA 02115, USA; e-mail: firstname.lastname@example.org