Evidence for selective expression of angiotensin II receptors on atretic follicles in the rat ovary: an autoradiographic study

• Published in: Endocrinology (Philadelphia) Vol. 122; no. 6; p. 2727
• Main Authors: Daud, A I, Bumpus, F M, Husain, A
• Format: Journal Article
• Language: English
• Published: United States 01.06.1988
• Subjects: 1-Sarcosine-8-Isoleucine Angiotensin II - metabolism; Angiotensin II - metabolism; Animals; Cell Membrane - metabolism; Epithelium - metabolism; Estrus - metabolism; Female; Follicle Stimulating Hormone - metabolism; Follicular Atresia; Follicular Phase; Iodine Radioisotopes; Ovarian Follicle - anatomy & histology; Ovarian Follicle - metabolism; Ovary - metabolism; Rats; Rats, Inbred Strains; Receptors, Angiotensin - metabolism; Receptors, FSH - metabolism; Tissue Distribution
• ISSN: 0013-7227
• DOI: 10.1210/endo-122-6-2727

Ovarian angiotensin II (Ang II) receptors display a cyclical pattern of variation during the rat estrous cycle. Ang II receptors, estimated by the specific binding of the Ang II receptor antagonist [125I]iodo-[Sar1,Ile8] Ang II to ovarian membranes, were lowest at estrus [binding site density (Bmax) = 35 +/- 2 fmol/mg; binding site affinity (KD) = 2.0 +/- 0.2 nM] and highest at diestrus I (Bmax = 59 +/- 3 fmol/mg; KD = 1.6 +/- 0.1 nM). We have previously shown that Ang II receptors in the rat ovary predominantly exist on the granulosa cell layer of a subpopulation of follicles. Our present studies show that the Ang II receptor-containing follicles in the rat ovary are mainly atretic (approximately 80%) or show signs of early atresia (approximately 15%) during all stages of the estrous cycle. A small number of Ang II receptor-containing follicles were healthy (approximately 5%). In contrast to the Ang II receptor-containing follicles, the FSH receptor-containing follicles were predominantly healthy (greater than 90%). Follicles which contained both Ang II receptors and FSH receptors were mainly early atretic. Since Ang II receptor-containing follicles in the rat ovary were mainly atretic these studies suggest that in the rat Ang II may be a major factor in regulating the function of atretic ovarian follicles.