Vol. 11, Special Issue 7 (2022)

Author(s):
Hitesh, Harender Singh and Garima Kansal

Abstract:
The hypothalamic-pituitary-gonadal axis (HPG axis) alludes to the connection between the hypothalamus, pituitary gland, and gonads. A number of intrinsic and extrinsic factors are integrated in the HPG axis that regulates the core functions of the reproductive system. A wide variety of GnRH modulators are already in practice but desired level of response is not achieved mostly due to their action at the downstream of HPG axis. In the recent past, novel neuro-peptide molecules like kisspeptin, phoenixin, etc. have been identified. The localization pattern of these molecules suggests a key role in the upstream of hypothalamic nuclei to regulate the reproductive processes. In farm animals, Kisspeptin plays a wide variety of actions, mainly regulating GnRH-mediated gonadotrophin release during onset of puberty, induction of estrus in the breeding seasonand extra-hypothalamic regulation of ovarian functions. Natural Kisspeptin molecules have limited therapeutic applications owing to their shorter half-life leading to the development of a series of synthetic Kisspeptin analogues. A few studies on kisspeptin agonists, namely Compound-6 and Compound-17 showed better performance in ovine, caprine and laboratory animal model over the natural kisspeptin. Recently, Kisspeptin antagonists (P²³⁴) have also been used in in vivo studies showing promising effect in controlling GnRH mediated LH surge. Emerging evidence suggests use of Kp and other neuropeptide analogues in the therapeutic protocols of controlled reproduction programs in several farm animal species. Thus, there is a need to put more efforts in the optimization of promising GnRH modulators for use in farm animals in order to augment reproductive efficiency.