Orexin 1 receptor in the seminiferous tubules of boar testis: An immunohistochemical study.

Orexin receptor 1 (OX1R) and orexin receptor 2 (OX2R) are two G-protein-coupled receptors that bindtheir ligands, orexin A (OXA) and B (OXB), with different affinities. The male genital system representsan important target for OXA, which appears to play a role in the control of steroidogenesis and germ celldevelopment in the testis. It is known that among domestic breeding animals, in the boar the numberof Leydig cells is very high and OXA appears to have stimulatory activity on testosterone production. Inthis study, we aimed to evaluate the presence of OX1R in the boar testis in order to extend our knowl-edge concerning the distribution and a potential functional role of the orexinergic system in the malereproductive tract of farm animals. The presence of OX1R immunopositive cells in seminiferous tubulesof the boar testis enables us to hypothesize a possible role of OXA on male germ cells cycle in pig. Furtherinvestigations, involving functional and ultrastructural analysis, may contribute to our understanding ofthe role of orexins in the boar genital system.