title: Expression of orexin B and its receptor 2 in rat testis.
abstract: The peptides orexin A (OxA) and orexin B (OxB) deriving from a common precursor molecule, prepro-orexin, by proteolytic cleavage, bind the two G-coupled OX1and OX2receptors. While OX1selectively binds OxA, OX2shows similar affinity for both orexins. Firstly discovered in the hypothalamus, orexins and their receptors have been found in other brain regions as well as in peripheral tissues of mammals, thus resulting involved in the regulation of a broad variety of physiological functions. While the functional localization of OxA and OX1in the mammalian genital tract has been already described, the expression of OxB and OX2and their potential role in the reproductive functions remain to be explored. Here, we investigated the presence of OxB and OX2in the rat testis by immunohistochemical and biochemical analyses. The results definitely demonstrated the localization of OxB and OX2in pachytene and second spermatocytes as well as in spermatids at all stages of the cycle of the seminiferous epithelium. The expression of both OX2mRNA and protein in the rat testis was also established by RT-PCR and Western blotting, respectively. The analysis of the molecular mechanism of action of OxB in the rat testis showed that OxB, in contrast with OxA, is unable to promote steroidogenesis. These results translate into the regulation of diverse biological actions by OxA and OxB in the male gonad.
authors.affiliation: Department of Veterinary Medicine and Animal Productions, University of Naples Federico II, Via F. Delpino 1, 80137 Naples, Italy.
authors.forename: Giovanna
authors.initials: G
authors.lastname: Liguori
authors.affiliation: Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, Via Pansini 5, 80131 Naples, Italy.
authors.forename: Luigi Michele
authors.initials: LM
authors.lastname: Pavone
authors.affiliation: Department of Biology, University of Naples Federico II, Via Mezzocannone 6, 80134 Naples, Italy.
authors.forename: Loredana
authors.initials: L
authors.lastname: Assisi
authors.affiliation: School of Agricultural, Forestry, Food and Environmental Sciences, University of Basilicata, Viale dell'Ateneo Lucano 10, 85100 Potenza, Italy.
authors.forename: Emilia
authors.initials: E
authors.lastname: Langella
authors.affiliation: Department of Veterinary Medicine and Animal Productions, University of Naples Federico II, Via F. Delpino 1, 80137 Naples, Italy.
authors.forename: Simona
authors.initials: S
authors.lastname: Tafuri
authors.affiliation: Department of Veterinary Medicine and Animal Productions, University of Naples Federico II, Via F. Delpino 1, 80137 Naples, Italy.
authors.forename: Nicola
authors.initials: N
authors.lastname: Mirabella
authors.affiliation: Department of Veterinary Medicine and Animal Productions, University of Naples Federico II, Via F. Delpino 1, 80137 Naples, Italy.
authors.forename: Anna
authors.initials: A
authors.lastname: Costagliola
authors.affiliation: Department of Veterinary Medicine and Animal Productions, University of Naples Federico II, Via F. Delpino 1, 80137 Naples, Italy. Electronic address: avittori@unina.it.
authors.forename: Alfredo
authors.initials: A
authors.lastname: Vittoria
mesh_terms: D000818:Animals; D007031:Hypothalamus / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D008297:Male; D009479:Neuropeptides / Q000378:metabolism; D064446:Orexin Receptors / Q000235:genetics / Q000378:metabolism*; D000068797:Orexins / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D043562:Receptors, G-Protein-Coupled / Q000235:genetics; D018013:Receptors, Neuropeptide / Q000378:metabolism; D013087:Spermatids / Q000378:metabolism; D013737:Testis / Q000378:metabolism*
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; D009479:Neuropeptides; D064446:Orexin Receptors; D000068797:Orexins; D043562:Receptors, G-Protein-Coupled; D018013:Receptors, Neuropeptide
keywords: Orexin 2 receptor; Orexin B; Rat; Steroidogenesis; Testis