Implications of neuropeptide Y in the regulation of testicular functions in wall lizard, Hemidactylus flaviviridis.

Abstract

The testicular functions of neuropeptide Y are largely unexplored in non-mammalian vertebrates as the few reports available remain restricted to fishes. Current research work reveals the testicular presence of npy and npyr in Hemidactylus flaviviridis and its variation in expression depending upon reproductive phases, marking the first documentation of such findings in reptilian species. Expression analysis of npy/npyr across different reproductive phases showed peak levels of both ligand and receptor during the recrudescent period, while the lowest expression occurred in regression. The investigation also examined the influence of NPY on markers of testicular spermatogenesis and steroidogenesis in H. flaviviridis. The in vitro exposure of wall lizard testes to NPY during recrudescent phase stimulated bcl 2, while simultaneously reduced caspase 3. NPY treatment also stimulated testicular expression of scf, c-kit, pcna, bmp-15 and gdf-9, along with gonadotropin receptor (fshr), and sex-steroid receptors (er-α, er-β, and ar). Further, NPY elevated star expression and promoted testosterone synthesis in wall lizard. Regarding the regulation of testicular npy and its receptor, npyr the expression of both ligand and its receptor was upregulated by the neuropeptide, kisspeptin, adipokines like leptin and nesfatin-1, and sex steroids such as DHT, and E2, while they were suppressed by the gonadotropin, FSH and the neuropeptide, substance P. Overall, this investigation provides a detailed documentation of the presence, phase-specific pattern of expression, role, and hormonal regulation of NPY and its receptor in wall lizard testes.