Localization of Angiotensin II Receptors in Ovarian Follicles and the Identification of Angiotensin II in Rat Ovaries

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 84; no. 8; pp. 2489 - 2493
• Main Authors: Husain, Ahsan, Bumpus, F. Merlin, De Silva, Preenie, Speth, Robert C.
• Format: Journal Article
• Language: English
• Published: Washington, DC National Academy of Sciences of the United States of America 01.04.1987; National Acad Sciences
• Subjects: Adrenal glands; angiotensin II; Angiotensin II - metabolism; Animals; Binding sites; Biological and medical sciences; Blood plasma; Cell receptors; Cell structures and functions; Female; Follicles; Fundamental and applied biological sciences. Psychology; Granulosa cells; Hormones; Kinetics; Molecular and cellular biology; Ovarian Follicle - metabolism; Ovaries; ovary; Ovary - cytology; Rats; Rats, Inbred Strains; Receptors; Receptors, Angiotensin - metabolism; Renin angiotensin system; Theca cells; Ovary; Vertebrata; Mammalia; Rat; Animal; Rodentia; Peptide hormone; Identification; Angiotensin II; Localization; Ovarian follicle; Hormonal receptor
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.84.8.2489

Specific, high-affinity (Kd≈ 0.6 nM), and saturable (3.3 fmol/mg of tissue, wet weight) binding of125I-labeled [Sar1, Ile8]angiotensin II to rat ovarian membranes was observed. Displacement of125I-labeled [Sar1,Ile8]angiotensin II binding to rat ovarian membranes by angiotensin II analogs and fragments resembled the potency order of these compounds on angiotensin II receptors in other tissues: [Sar1,Ile8]angiotensin II > angiotensin II > des-Asp1-angiotensin II > angiotensin I > des-Asp1,Arg2-angiotensin II. Several unrelated peptides, including follicle-stimulating hormone at 10 μ M, did not displace ovarian125I-labeled [Sar1,Ile8]angiotensin II binding. Autoradiograms of125I-labeled [Sar1,Ile8]angiotensin II binding to ovarian sections indicated that the angiotensin II receptor binding sites were localized exclusively to a subpopulation of follicles, occurring on the granulosa and theca interna cells. Other follicles were devoid of125I-labeled [Sar1,Ile8]angiotensin II binding sites. Angiotensin II immunoreactive material was also identified in the ovary. The concentration of ovarian Ang II immunoreactivity was 8- to 75-fold greater than that of plasma, was not reduced in bilaterally nephrectomized rats, and was shown by high-pressure liquid chromatographic analysis to be the native angiotensin II octapeptide. The presence of angiotensin II and its receptor binding sites in the ovary suggests a role for angiotensin II as a regulator of ovarian function.