Gonadotropin-Releasing Hormone in the Ovary

Abstract

Gonadotropin-releasing hormone (GnRH) plays a pivotal role in the physiology of reproduction in mammals. GnRH acts by binding to the GnRH receptor (GnRHR). In humans, only 1 conventional GnRH receptor subtype (type I GnRH receptor) has been found. In the human genome, 2 forms of GnRH have been identified, GnRH-I (mammal GnRH) and GnRH-II (chicken GnRH II). Both forms and their common receptor are expressed, apart from the hypothalamus, in various compartments of the human ovary. Gonadal steroids, gonadotropins, and GnRH itself controls the regulation of the GnRH/GnRHR system gene expression in the human ovary. The 2 types of GnRH acting paracrinally/autocrinally influence ovarian steroidogenesis, decrease the proliferation, and induce apoptosis of ovarian cells. In this review, the biology of GnRH/GnRHR system in humans, the potential roles of GnRH, and the direct effects of GnRH analogues in ovarian cells are discussed.

Gonadotropin releasing hormone antagonists suppress aromatase and anti-Müllerian hormone expression in human granulosa cells

“…Most vertebrate species possess at least two and usually three forms of GnRH (43)(44)(45). In humans, in addition to GnRH-I, GnRH-II has been identified (45)(46)(47)(48)(49).…”

“…In humans, in addition to GnRH-I, GnRH-II has been identified (45)(46)(47)(48)(49). The most prominent difference in the tissue distribution of GnRH-I and GnRH-II in humans is that the latter is expressed at the highest level outside the brain while GnRH-I is expressed mainly in the brain (44). The GnRHR belongs to a member of the rhodopsin-like G protein-coupled receptor superfamily, which responds both to GnRH-I and GnRH-II (50).…”

Thymic Involution: Where Endocrinology Meets Immunology

“…LHRH binds LHRH receptors (LHRH-R) in the anterior pituitary gland [34] . Upon stimulation, the pituitary gland then produces luteinizing hormone (LH) and folliclestimulating hormone (FSH).…”

“…These in turn regulate the production of the sex steroids testosterone, progesterone and oestrogen. Each of these steroids has a negative impact on the thymus and the bone marrow [34] and their production is controlled by a negative feedback loop. Accordingly LHRH has been a major target for clinical intervention and this has now been achieved safely and efficaciously via agonist and antagonist LHRH variants [36] .…”

The effect of human cumulus cells on the maturation and developmental potential of immature oocytes in ICSI cycles

“…For the in vitro maturation of human oocytes, the media has been supplemented with HMG [25], pregnant mare serum gonadotropin [3], HCG [3,21], FSH and LH [15,21], and E2 [3,21]. However, the receptors for many of these molecules are on the CCs [5,20], which implies that the supplements may not play a full role for cumulus-free oocytes. Based on this opinion, HTF medium supplemented with 10% SSS, without additional supplements, was used to culture immature oocytes.…”