title: Novel identification of peripheral dopaminergic D2 receptor in male germ cells.
abstract: Dopamine is a recognized modulator in the central nervous system (CNS) and peripheral organ functions. The presence of peripheral dopamine receptors outside the CNS has suggested an intriguing interaction between the nervous system and other functional systems, such as the reproductive system. In the present study we analyzed the expression of D2R receptors in rat testis, rat spermatogenic cells and spermatozoa, in different mammals. The RT-PCR analysis of rat testis mRNA showed specific bands corresponding to the two dopamine receptor D2R (L and S) isoforms previously described in the brain. Using Western blot analysis, we confirmed that the protein is present in rat testis, isolated spermatogenic cells and also in spermatozoa of a range of different mammals, such as rat, mouse, bull, and human. The immunohistochemistry analysis of rat adult testis showed that the receptor was expressed in all germ cells (pre- and post-meiotic phase) of the tubule with staining predominant in spermatogonia. Confocal analysis by indirect immunofluorescence revealed that in non-capacitated spermatozoa of rat, mouse, bull, and human, D2R is mainly localized in the flagellum, and is also observed in the acrosomal region of the sperm head (except in human spermatozoa). Our findings demonstrate that the two D2 receptor isoforms are expressed in rat testis and that the receptor protein is present in different mammalian spermatozoa. The presence of D2R receptors in male germ cells implies new and unsuspected roles for dopamine signaling in testicular and sperm physiology.
authors.affiliation: Instituto de Bioquímica, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile.
authors.forename: Carola
authors.initials: C
authors.lastname: Otth
authors.forename: Mauricio
authors.initials: M
authors.lastname: Torres
authors.forename: Alfredo
authors.initials: A
authors.lastname: Ramírez
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Fernandez
authors.forename: Maite
authors.initials: M
authors.lastname: Castro
authors.forename: M Cecilia
authors.initials: MC
authors.lastname: Rauch
authors.forename: Mónica
authors.initials: M
authors.lastname: Brito
authors.forename: Alejandro J
authors.initials: AJ
authors.lastname: Yañez
authors.forename: Joan-Enric
authors.initials: JE
authors.lastname: Rodríguez-Gil
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Slebe
authors.forename: Ilona I
authors.initials: II
authors.lastname: Concha
mesh_terms: D000818:Animals; D002417:Cattle; D006801:Humans; D008297:Male; D051379:Mice; D020033:Protein Isoforms / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D017448:Receptors, Dopamine D2 / Q000378:metabolism*; D013087:Spermatids / Q000378:metabolism; D013094:Spermatozoa / Q000378:metabolism*; D013737:Testis / Q000378:metabolism*
chemical_list: D020033:Protein Isoforms; D012333:RNA, Messenger; D017448:Receptors, Dopamine D2