Gonadotropin-releasing hormone 1 (GNRH1), also known as Luteinising-hormone releasing hormone (LHRH), is a peptide hormone responsible for the release of FSH and LH from the anterior pituitary. GNRH1 is synthesized and released by the hypothalamus.
At the pituitary, GNRH1 stimulates the synthesis and secretion of the gonadotropins follicle-stimulating hormone (FSH) and luteinizing hormone (LH). These processes are controlled by the size and frequency of GNRH1 pulses, as well as by feedback from androgens and estrogens. Low requency GNRH1 pulses lead to FSH release, whereas high frequency GNRH1 pulses stimulate LH release.
There are differences in GNRH1 secretion between males and females. In males, GNRH1 is secreted in pulses at a constant frequency, but in females the frequency of the pulses varies during the menstrual cycle and there is a large surge of GNRH1 just before ovulation.
GNRH1 secretion is pulsatile in all vertebrates, and is necessary for correct reproductive function. Thus, a single hormone, GNRH1, controls a complex process of follicular growth, ovulation, and corpus luteum maintenance in the female, and spermatogenesis in the male.