The localization and expression of gonadotropin-inhibitory hormone in the hypothalamus of turkey-hens during the pre-pubertal, pubertal and post-pubertal phases

Abstract Gonadotropin inhibitory hormone (GnIH), initially discovered in birds as a hypothalamic neuropeptide, inhibits the synthesis and release of gonadotropins via affecting the GnRH neurons and gonadotropes. Therefore, it could be a key neuropeptide in reproduction in birds. The aim of the present study was to investigate the prepubertal, pubertal, and postpubertal localization of GnIH and changes in hypothalamic GnIH expression in British United Turkey hens. In prepubertal, pubertal, and postpubertal periods, the brains of turkey hens (n = 15) were removed after fixation. Sections (30 μm) were prepared from the entire hypothalamus and stained immunohistochemically against GnIH antibody. Gonadotropin inhibitory hormone–immunoreactive neurons were observed in the paraventricular nucleus. These neurons were significantly more abundant in the prepubertal turkeys than pubertal and postpubertal turkeys (P