title: Expression and role of receptor 1 for orexins in seminiferous tubules of rat testis.
abstract: Orexins (OxA and OxB) and their receptors (Ox1R and Ox2R), originally detected in the hypothalamus, have also been localized in multiple cerebral areas and peripheral organs. Thus, in addition to their central function in the regulation of food intake, arterial blood pressure, heart rate, sleep/wake cycle, sexual behaviour, arousal, and hypothalamic/hypophyseal axis, these neuropeptides may exert a local action in various peripheral organs and tissues. Emerging evidence suggests a main role of OxA and its highly specific receptor Ox1R in the male genital tract of mammals. We previously demonstrated OxA localization in Sertoli cells and spermatids of rat testis. Here, we show positive stainings of Ox1R in developing spermatocytes, and spermatids of rat testis by immunohistochemistry. The expression of Ox1R mRNA and the protein in the tissue was also established by reverse-transcription polymerase chain reaction and Western blotting respectively. The addition of OxA to fresh testis slices significantly increased testosterone (T) secretion which, conversely, was inhibited by Mullerian inhibiting substance (MIS). The sequential treatment of testis samples with the two substances highlighted an antagonizing activity of OxA versus MIS in regulating T levels. Furthermore, the stimulating effect on T production by OxA was prevented by the addition of the selective Ox1R inhibitor SB-408124. Overall, our findings suggest that locally secreted OxA interacting with Ox1R activates signals which antagonize MIS action in the control of T levels in mammalian testis.
authors.affiliation: Department of Biological Sciences, University of Naples Federico II, Naples, Italy.
authors.forename: Loredana
authors.initials: L
authors.lastname: Assisi
authors.forename: Simona
authors.initials: S
authors.lastname: Tafuri
authors.forename: Giovanna
authors.initials: G
authors.lastname: Liguori
authors.forename: Salvatore
authors.initials: S
authors.lastname: Paino
authors.forename: Luigi Michele
authors.initials: LM
authors.lastname: Pavone
authors.forename: Norma
authors.initials: N
authors.lastname: Staiano
authors.forename: Alfredo
authors.initials: A
authors.lastname: Vittoria
mesh_terms: D000818:Animals; D054304:Anti-Mullerian Hormone / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D047908:Intracellular Signaling Peptides and Proteins / Q000494:pharmacology; D008297:Male; D009479:Neuropeptides / Q000494:pharmacology; D064446:Orexin Receptors; D000068797:Orexins; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D043562:Receptors, G-Protein-Coupled / Q000235:genetics / Q000378:metabolism*; D018013:Receptors, Neuropeptide / Q000235:genetics / Q000378:metabolism*; D012671:Seminiferous Tubules / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D013087:Spermatids / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D013090:Spermatocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D013739:Testosterone / Q000378:metabolism
chemical_list: C578627:Hcrtr1 protein, rat; D047908:Intracellular Signaling Peptides and Proteins; D009479:Neuropeptides; D064446:Orexin Receptors; D000068797:Orexins; D012333:RNA, Messenger; D043562:Receptors, G-Protein-Coupled; D018013:Receptors, Neuropeptide; D013739:Testosterone; D054304:Anti-Mullerian Hormone