Coexpression of gonadotropin inhibitory hormone with Agouti-related peptide in the neurons of arcuate nucleus of ewe hypothalamus

Introduction: Gonadotropin inhibitory hormone (GnIH) and Agouti-related peptide (AgRP) are orexigenic peptides expressed in the arcuate nucleus (Arc) of the hypothalamus in the ewe. In addition, effects of GnIH and AgRP on the regulation of gonadotropin releasing hormone secretion have been shown in some mammals. The objective of the present study was to investigate the coexpression of GnIH and AgRP in Arc of the ewe hypothalamus. Methods: Nine ewes were divided into follicular, luteal, and ovariectomised groups (n = 3 each group) and the number of neurons that express GnIH and AgRP and the percentage of coexpression of these two peptides in the Arc of each group was estimated by using immunohistochemistry. Results: In different ovarian conditions of ewes, 19 to 32 percent of GnIH and AgRP neurons were coexpressed in the Arc of the hypothalamus. Conclusion: Results of the present study showed a possible cooperative role of AgRP and GnIH in the Arc of the hypothalamus in regulation of ovarian function in ewe.