Angiotensin II: does it have a direct obligate role in ovulation?

Department of Obstetrics and Gynecology, Yale University, New Haven, CT 06510-8063.
Science (Impact Factor: 31.03). 09/1989; 245(4920):870-1. DOI: 10.1126/science.245.4920.871
Source: PubMed
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    ABSTRACT: It has long been known that angiotensin II (Ang II) can affect reproductive tissues such as the uterus. However, the existence of a local renin–angiotensin system (RAS) in female as well as male reproductive tissues is a relatively recent observation. Of great interest is the discovery that all components of the RAS are present in the ovary, that the ovary secretes components of the RAS into the bloodstream, and that the ovary itself is responsive to Ang II. Recent studies suggest that the primary role of Ang II in the ovary is to cause atresia in non-ovulatory follicles; however, there is also compelling data to suggest that Ang II facilitates ovulation. Male reproductive structures also contain all of the components of the RAS, gonadotropins regulate the activity of these components, and these tissues have Ang II receptors. Of great interest is the expression of testis-specific angiotensin-converting enzyme (ACE), which is located on germ cells. Recent studies using gene knock-out techniques indicate that testis ACE plays an important role in male fertility. However, the overall significance of the RAS for normal reproductive function remains questionable. There is now a body of evidence implicating the RAS in pathophysiologies associated with reproductive function, which gives rise to the possibility that drugs acting on the RAS might ameliorate some of these disorders. Considerable work remains to determine the role of Ang II in reproductive functions.
    Regulatory Peptides - REGUL PEPTIDES. 01/1999; 79(1):25-40.
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    ABSTRACT: SUMMARY1. In previous studies we have demonstrated and solved several methodological problems in relation to the measurement of prorenin by trypsin activation in rat, bovine, hog and horse plasma.2. The aim of the present study was to develop a method for the measurement of prorenin in bovine and porcine ovarian follicular fluid.3. Trypsin activation of follicular fluid generated angiotensin I immunoreactive material (AI IM) in both species.4. The AI IM interfered with the renin assay, but could be completely removed by a cation exchange resin in a batch-wise technique.5. The enzymatic activity of trypsin-activated prorenin and pre-existing active renin was completely inhibited by a specific inhibitor of renin.6. The reactions were optimized and an accurate measurement of prorenin in ovarian follicular fluid was developed.7. The existence of prorenin and renin in bovine ovarian follicular fluid was established. Prorenin and renin in porcine ovarian follicular fluid was demonstrated for the first time.8. The ratio between ovarian follicular fluid and plasma was 43 for prorenin and 19 for active renin in cattle. The same ratios in pigs were 1.3 and 0.4, respectively. These findings indicate a species difference with respect to the amount of prorenin or active renin present in ovarian follicular fluid.
    Clinical and Experimental Pharmacology and Physiology 03/1992; 19(4):267 - 273. · 2.41 Impact Factor
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    ABSTRACT: The ovarian renin-angiotensin system (RAS) has been studied extensively in the virgin cycling rat, but little information is available about this system in pregnant and postpartum rats. We show that renin and angiotensin I-converting enzyme (ACE)--the key enzymes involved in angiotensin II (Ang II) formation--and Ang II receptors, are present in pregnant and postpartum rat ovaries. From gestation Days 2-4 to 10-12, active ovarian renin ranged from 1.12 +/- 0.13 to 1.27 +/- 0.19 ng Ang I/h/mg and comprised between 68 and 86% of total (active+inactive) ovarian renin activity. Between Days 10-12 and Days 14-16 of pregnancy, ovarian active renin activity increased slightly, but inactive renin disappeared, suggesting its activation; the remaining active renin then decreased 62% by Days 18-20 (p < 0.05). On postpartum Day 2, both active and total ovarian renin activity exceeded that of Days 2-20 of pregnancy (p < 0.05); levels of both then declined sharply by postpartum Day 3 (p < 0.05). In pregnant rats, levels of ovarian Ang II receptors, identified by the specific binding of [125I]-[Sar1,Ile8]Ang II to ovarian membranes, were high between Days 2-4 and 10-12 of pregnancy, ranging from 12.8 +/- 1.7 to 15.7 +/- 3.4 fmol/mg, but steadily declined by 82% between gestation Days 10-12 and 18-20 (p < 0.05). Postpartum Ang II receptor levels on Days 2, 3, and 4 showed a gradual increase from low levels comparable to Days 18-20 of pregnancy. Ovarian ACE activity did not change throughout pregnancy or during the postpartum period.(ABSTRACT TRUNCATED AT 250 WORDS)
    Biology of Reproduction 01/1993; 47(6):925-30. · 4.03 Impact Factor