Abstract
Kisspeptin (Kp) is synthesized in the arcuate nucleus and preoptic area of the hypothalamus and is a regulator of gonadotropin releasing hormone in the hypothalamus. In addition, Kp may regulate additional functions such as increased neuropeptide Y gene expression and reduced proopiomelanocortin (POMC) gene expression in sheep. Other studies have found a role for Kp to release growth hormone (GH), prolactin and luteinizing hormone (LH) from cattle, rat and monkey pituitary cells. Intravenous injection of Kp stimulated release LH, GH, prolactin and follicle stimulating hormone in some experiments in cattle and sheep, but other studies have failed to find an effect of peripheral injection of Kp on GH release. Recent studies indicate that Kp can stimulate GH release after intracerebroventricular injection in sheep at doses that do not release GH after intravenous injection. These studies suggest that Kp may have a role in regulation of both reproduction and metabolism in sheep. Since GH plays a role in luteal development, it is tempting to speculate that the ability of Kp to release GH and LH is related to normal control of reproduction.
Highlights
Kisspeptin (Kp), known as metastin, was first discovered and noted for its role in the inhibition of cancer cell metastasis
Neuroendocrine control of reproduction in ruminants culminates in the secretion of luteinizing hormone (LH) from the anterior pituitary
Kisspeptin expression is regulated by steroids as the number of Kp positive cells in the ARC are increased following OVX compared to intact ewes, the opposite being found in the preoptic area (POA) Kp neurons [8]
Summary
Kisspeptin (Kp), known as metastin, was first discovered and noted for its role in the inhibition of cancer cell metastasis. Kisspeptin expression is regulated by steroids as the number of Kp positive cells in the ARC are increased following OVX compared to intact ewes, the opposite being found in the preoptic area (POA) Kp neurons [8]. Expression of the Kp receptor, Kiss1r, mRNA in GnRH neurons is higher during the nonbreeding season than during the breeding season in ewes, and Kiss1r mRNA expression in GnRH neurons is reduced by Kp-10 treatment of ewes during the non-breeding season but not by steroid treatment of OVX ewes [17] These results suggest alterations in Kp production or release is involved in the seasonal regulation of reproduction in sheep. Kisspeptin is released into the portal vein circulation of sheep [11] the timing of Kp pulses was concurrent with or follow the LH pulses This may suggest that Kp is regulating some pituitary function other than stimulating LH via GnRH action.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
