Distribution of gonadotropin-inhibitory hormone (GnIH) in male Luchuan piglets

Gonadotropin inhibitory hormone (GnIH) has emerged as a novel hypothalamic neuropeptide that actively inhibits gonadotropin release in birds and mammals. Recent evidence indicates that GnIH not only acts as a key neurohormone that controls vertebrate reproduction but is also involved in stress response, food intake, and aggressive and sexual behaviors, suggesting a broad physiological role for this neuropeptide. To elucidate its multiple sites of action and potential functions, studying the detailed distribution of GnIH in different organs, except for the hypothalamus-pituitary-ovary/testis axis, is necessary. Therefore, in the present study, in different central nervous system (CNS) and peripheral organs of male Luchuan piglets, the distribution of GnIH was systemically determined using immunohistochemistry, and the expression of GnIH mRNA was investigated using semi-quantitative reverse transcription polymerase chain reaction (RT-PCR). Our results demonstrate that GnIH immune reactive (GnIH-ir) neurons were widely distributed in the pig CNS, but the number and size of the GnIH-ir neurons varied and exhibited morphological diversity. In the peripheral organs, GnIH immunoreactive cells were observed in the respiratory tract, alimentary tract, endocrine organs, genitourinary tract and lymphatic organs. GnIH mRNA was highly expressed in the CNS, with the highest expression in the hypothalamus. In the peripheral organs, high GnIH mRNA levels were detected in the testis, while no GnIH expression was observed in the liver, lungs and heart et al. These results demonstrated that GnIH might play an important role in modulating a variety of physiological functions and provided the morphological data for further study of GnIH in pigs.