The role of kisspeptin in the hypothalamic pituitary ovarian axis in buffalo cow reproduction

Abstract

Kisspeptin is a neuropeptide and is produced from the Kiss1 gene in hypothalamic nuclei found mainly in the preoptic area (POA) and the arcuate nucleus (ARC). It has been found to control the hypothalamic pituitary gonadal axis in mammals. Although in the last decade there have been many studies done on kisspeptin, and it remains a major topic in reproductive research, no studies have been done on kisspeptin in buffalo. This study investigated the role of kisspeptin in the hypothalamic pituitary ovarian axis in the cycling buffalo cows. In vitro research found evidence of Kiss1 mRNA using the in situ hybridization technique and kisspeptin protein using the immunohistochemistry technique in the hypothalamic nuclei (POA and ARC) of buffaloes. Moreover, structural interactions were found between kisspeptin receptors and gonadotropin releasing hormone (GnRH) neurons as revealed by double immunofluorescent in the same areas. Also, the localization and distribution of estrogen receptors and progesterone receptors in the POA and ARC as well as GnRH receptors in the anterior pituitary glands were detected by immunohistochemistry. In an in vivo study, the luteinizing hormone response to a single intravenous injection of kisspeptin-10 showed a variable response in early luteal phase buffalo cows and was less than the usual response to a GnRH intramuscular injection. These results suggest that kisspeptin is related to buffalo cow reproduction. This study indicates that kisspeptin may be involved in the HPO axis and may influence reproductive functions in buffalo cows.