Immunocytochemical Detection of Kisspeptin Receptor and Its Association with Motility of Buffalo Bull (Bubalus bubalis) Spermatozoa

Kisspeptin is a powerful regulator of the hypothalamic-pituitary-gonadal axis. It acts through its receptor GPR54 to regulate sexual maturation, oogenesis, spermatogenesis and fertilization. The present research was implemented to evaluate the presence of kisspeptin receptor on various regions of buffalo bull spermatozoa and to decipher its relationship with different motility parameters of the fresh spermatozoa. Standard swim-up protocol was performed on fresh ejaculates from Nili-Ravi buffalo bulls to obtain three hypothetical layers, having spermatozoa with enhanced motility and normal morphology. The progressive sperm motility was measured in each layer by using phase contrast microscopy. Methanol fixed sperm smears from each layer were processed for standard immunocytochemistry procedure for the detection of kisspeptin receptor using specific antibodies. Maximum GPR54 immunoreactivity was observed in the upper regions (head, neck/midpiece) and moderate immunoreactivity was seen in the lower region (tail) of the spermatozoa in all the three layers. No significant difference in total GPR54 expression was observed in the spermatozoa from three layers and no relationship was observed between percentage motility and GPR54 like ir. Present findings suggest that the buffalo sperm motility is not influenced by GPR54 expression on different regions of the sperm. However, robust GPR54 expression in dorsal areas of buffalo sperm, would raise possibility of a covert function of kisspeptin in the bubaline sperm biology. (C) 2019 PVJ. All rights reserved