Localization of angiotensin II receptors in ovarian follicles and the identification of angiotensin II in rat ovaries.
Specific, high-affinity (Kd approximately equal to 0.6 nM), and saturable (3.3 fmol/mg of tissue, wet weight) binding of 125I-labeled [Sar1,Ile8]angiotensin II to rat ovarian membranes was observed. Displacement of 125I-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 greater than angiotensin II greater than des-Asp1-angiotensin II greater than angiotensin I greater than des-Asp1,Arg2-angiotensin II. Several unrelated peptides, including follicle-stimulating hormone at 10 microM, did not displace ovarian 125I-labeled [Sar1,Ile8]angiotensin II binding. Autoradiograms of 125I-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 of 125I-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.
Husain
A
A
Bumpus
F M
FM
De Silva
P
P
Speth
R C
RC
D000804:Angiotensin II / Q000378:metabolism*; D000818:Animals; D005260:Female; D007700:Kinetics; D006080:Ovarian Follicle / Q000378:metabolism*; D010053:Ovary / Q000166:cytology; D051381:Rats; D011919:Rats, Inbred Strains; D011945:Receptors, Angiotensin / Q000378:metabolism*
D011945:Receptors, Angiotensin; D000804:Angiotensin II