Gonadotropin-releasing hormone (GnRH) regulates the production of testosterone via the hypothalamic-pituitary-gonadal axis and testosterone, in turn, regulates the GnRH system via negative feedback. We compared testosterone regulation of GnRH mRNA expression in four anatomically defined GnRH cell groups in juvenile and adult male Syrian hamsters, including a rostral population of GnRH cells in ...

The immortalized GT1-7 cell line synthesizes and secretes GnRH, the key hormone of reproduction. However, GT1-7 cells lack the normal inputs from neurotransmitters, growth factors, and steroids, which are involved in the maturation and maintenance of GnRH neurons in the brain. We examined the effects of the neurotrophic factor insulin-like growth factor-I (IGF-I) on GnRH gene expression and the...

background: polycystic ovarian syndrome (pcos) patients are prone to premature lh surge and ovarian hyperstimulation syndrome (ohss). long gnrh analogue protocol and gnrh antagonist protocol are two methods utilized for induction ovulation in patients undergoing ivf/icsi. objective: the aim of this study was to compare the effects of gnrh agonists and antagonists in pcos patients. materials and...

In human beings, two forms of GnRH, termed GnRH-I and GnRH-II, encoded by separate genes have been identified. Although these hormones share comparable cDNA and genomic structures, their tissue distribution and regulation of gene expression are significantly dissimilar. The actions of GnRH are mediated by the GnRH receptor, which belongs to a member of the rhodopsin-like G protein-coupled recep...

Quantitative in vitro autoradiography was used to characterize and localize putative GnRH receptors in the anterior pituitary of the adult female sea lamprey, Petromyzon marinus. Pituitaries were sectioned at 20 microns and incubated for 3 h at 4 C with DAla6,Pro9 NEt mammalian GnRH as both the labeled and unlabeled ligand. Scatchard analysis revealed two classes of high affinity binding sites ...

The terminal nerve (TN)-gonadotropin-releasing hormone (GnRH) neurons project widely in the brain instead of the pituitary and show endogenous pacemaker activity that is dependent on the physiological conditions of the animal. We suggest that the TN-GnRH system may act as a putative neuromodulator that is involved in the regulation of many long-lasting changes in the animal's behavior. In the p...

Gonadotropin-releasing hormone (GnRH) signaling regulates reproductive physiology in mammals. GnRH is released by a subset of hypothalamic neurons and binds to GnRH receptor (GnRHR) on gonadotropes in the anterior pituitary gland to control production and secretion of gonadotropins that in turn regulate the activity of the gonads. Central control of reproduction is well understood in adult anim...

GT1-7 cells respond to treatment with the phorbol ester, phorbol 12-myristate 13-acetate (PMA), with an inhibition of transcription of the proGnRH gene and decreases in GnRH mRNA levels. However, the timing of this decrease in GnRH mRNA levels suggests that a decrease in GnRH mRNA stability may be involved in addition to an inhibition of transcription of the proGnRH gene. To address this possib...

Prader-Willi syndrome (PWS) is a complex genetic disorder characterized by hyperphagia, obesity and hypogonadotrophic hypogonadism, all highly suggestive of hypothalamic dysfunction. The NDN gene, encoding the MAGE family protein, necdin, maps to the PWS chromosome region and is highly expressed in mature hypothalamic neurons. Adult mice lacking necdin have reduced numbers of gonadotropin-relea...

GnRH is the master neuropeptide that coordinates and regulates reproduction in all vertebrates and in some nonvertebrate species. Sixteen forms of GnRH have been isolated in brain. In the vast majority of species, two or more forms occur in anatomically and developmental distinct neuronal populations. In mammalian brain, two GnRH forms, mammalian (GnRH-I) and chicken-II (GnRH-II), exist. The di...