title: Angiotensin-(1-7) induces ovulation and steroidogenesis in perfused rabbit ovaries.
abstract: A local renin-angiotensin system has been described in several organs, including the ovary; however, data indicating a role for angiotensin II in the induction of ovulation are controversial. We have previously shown the presence of a novel peptide, angiotensin-(1-7) [Ang-(1-7)], in the rat ovary and its effect on steroidogenesis. The objective of the present study was to determine whether Ang-(1-7) plays a role in ovulation. We first determined the presence and distribution of Ang-(1-7) and the receptor Mas in rabbit ovaries by immunohistochemistry. Angiotensin-(1-7) and Mas immunoreactivity were observed in interstitial cells and oocytes of immature ovaries. Immunoreactivity for Ang-(1-7) and Mas was also observed in theca and granulosa cells of preovulatory follicles in ovaries of gonadotrophin-stimulated rabbits. To verify the effect of Ang-(1-7) in ovulation and steroidogenesis, we used isolated ovaries from immature rabbits pretreated with equine chorionic gonadotrophin (50 i.u., 48 h before the experiment) and then perfused in vitro. The ovulatory efficiency was determined by the number of oocytes compared with the number of preovulatory follicles present in the ovary. Angiotensin-(1-7) stimulated oestradiol production and enhanced ovulatory efficiency, which was blocked by the specific Ang-(1-7) antagonist, A-779. Ovulation induced by human chorionic gonadotrophin was also antagonized by A-779. These results show, for the first time, the involvement of a novel regulatory peptide system, Ang-(1-7) and Mas, in the ovulatory process. More importantly, because A-779 antagonized hCG-induced ovulation, it may be inferred that Ang-(1-7) plays an important role in ovulation, possibly as a mediator of gonadotrophin action.
authors.affiliation: Department of Physiology and Biophysics, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.
authors.forename: Gregorio E N
authors.initials: GE
authors.lastname: Viana
authors.forename: Virginia M
authors.initials: VM
authors.lastname: Pereira
authors.forename: Kinulpe
authors.initials: K
authors.lastname: Honorato-Sampaio
authors.forename: Cleida A
authors.initials: CA
authors.lastname: Oliveira
authors.forename: Robson A S
authors.initials: RA
authors.lastname: Santos
authors.forename: Adelina M
authors.initials: AM
authors.lastname: Reis
mesh_terms: D000803:Angiotensin I / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000494:pharmacology*; D000804:Angiotensin II / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D004958:Estradiol / Q000096:biosynthesis*; D005260:Female; D006064:Gonadotropins, Equine / Q000494:pharmacology; D009865:Oocytes / Q000187:drug effects; D006080:Ovarian Follicle; D010053:Ovary / Q000187:drug effects* / Q000378:metabolism; D010060:Ovulation / Q000187:drug effects; D010446:Peptide Fragments / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000494:pharmacology*; D010477:Perfusion; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D011817:Rabbits; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism*
chemical_list: C092006:7-Ala-angiotensin (1-7); D006063:Chorionic Gonadotropin; D006064:Gonadotropins, Equine; D010446:Peptide Fragments; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins; D043562:Receptors, G-Protein-Coupled; D000804:Angiotensin II; D004958:Estradiol; D000803:Angiotensin I; C118790:angiotensin I (1-7)