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      Proliferation of the Superficial Epithelium of Ovaries in Senile Female Rats Following Oral Administration of Conjugated Equine Estrogens

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          Abstract

          OBJECTIVE

          To evaluate the effect of different concentrations of estrogen on the ovarian superficial epithelium in senile female rats. Design: Fifty female rats at 15 months of age and with irregular estrous cycles were selected and randomly divided into five experimental groups containing equal numbers of animals in each: GPROP, control group receiving vehicle only; GE0.05mg, group receiving conjugated equine estrogens (CEE) at a dose of 50 μg/kg; GE0.5mg, group receiving CEE at 500 μg/kg; GE1mg, group receiving CEE at 1 mg/kg; and GE2mg, receiving CEE at 2 mg/kg. The length of treatment was 21 days. After this period, the animals were anesthetized and the ovaries were fixed in 10% formaldehyde and processed for routine histology. Histomorphology was analyzed by light microscopy, and histomorphometrics were evaluated using the Imagelab program.

          RESULTS

          In the GPROP and GE0.05mg groups, the superficial epithelium of the ovary had a simple cuboidal shape, and as the estrogen dose increased, the epithelium thickened, with pseudo-stratified or stratified epithelium appearing in the GE2mg group. The animals in the group given the highest estrogen dose (GE2mg) showed the thickest ovarian epithelium and the largest perimeter and surface area of the surface ovarian epithelium ( P < 0.01). However, the difference in epithelium thickness between the GE0.5mg and GE1mg groups was only slight.

          CONCLUSION

          Our data suggest that CEE at a dose of 2 mg/kg may induce marked proliferation of rat ovarian epithelium.

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          Most cited references93

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          Hormonal etiology of epithelial ovarian cancer, with a hypothesis concerning the role of androgens and progesterone.

          H Risch (1998)
          In the United States, ovarian cancer is the fourth most frequent cause of cancer death among women, following lung, breast, and colorectal cancers. Each year, approximately 26,000 women are diagnosed with ovarian cancer and 14,000 die of it. Germline mutations in BRCA1, BRCA2, or other genes have been implicated in a small fraction of cases. However, it has been suggested that, for the great majority of patients, the risk of epithelial ovarian cancer could be related to "incessant ovulation" (i.e., to the chronically repeated formation of stromal epithelial clefts and inclusion cysts following ovulation) or to some type of hormonal stimulation of ovarian epithelial cells, either on the surface of the ovary or within ovarian inclusion cysts, possibly mediated through excessive gonadotropin secretion. From the evidence to date, the relative importance of these two hypotheses--incessant ovulation and gonadotropin stimulation--cannot be distinguished. While either or both may play a role in the development of ovarian cancer, it appears that an additional major factor must also be involved. The purpose of this review is to evaluate evidence for and against the incessant ovulation and gonadotropin hypotheses, as well as to consider the possibility that risk of ovarian cancer may be increased by factors associated with excess androgenic stimulation of ovarian epithelial cells and may be decreased by factors related to greater progesterone stimulation. Many features of the evidence bearing on the pathophysiology of ovarian cancer appear to support a connection with androgens and progesterone.
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            Cardiovascular disease outcomes during 6.8 years of hormone therapy: Heart and Estrogen/progestin Replacement Study follow-up (HERS II).

            The Heart and Estrogen/progestin Replacement Study (HERS) found no overall reduction in risk of coronary heart disease (CHD) events among postmenopausal women with CHD. However, in the hormone group, findings did suggest a higher risk of CHD events during the first year, and a decreased risk during years 3 to 5. To determine if the risk reduction observed in the later years of HERS persisted and resulted in an overall reduced risk of CHD events with additional years of follow-up. Randomized, blinded, placebo-controlled trial of 4.1 years' duration (HERS) and subsequent unblinded follow-up for 2.7 years (HERS II) conducted at outpatient and community settings at 20 US clinical centers. A total of 2763 postmenopausal women with CHD and average age of 67 years at enrollment in HERS; 2321 women (93% of those surviving) consented to follow-up in HERS II. Participants were randomly assigned to receive 0.625 mg/d of conjugated estrogens and 2.5 mg of medroxyprogesterone acetate (n = 1380), or placebo (n = 1383) during HERS; open-label hormone therapy was prescribed at personal physicians' discretion during HERS II. The proportions with at least 80% adherence to hormones declined from 81% (year 1) to 45% (year 6) in the hormone group, and increased from 0% (year 1) to 8% (year 6) in the placebo group. The primary outcome was nonfatal myocardial infarction and CHD death. Secondary cardiovascular events were coronary revascularization, hospitalization for unstable angina or congestive heart failure, nonfatal ventricular arrhythmia, sudden death, stroke or transient ischemic attack, and peripheral arterial disease. There were no significant decreases in rates of primary CHD events or secondary cardiovascular events among women assigned to the hormone group compared with the placebo group in HERS, HERS II, or overall. The unadjusted relative hazard (RH) for CHD events in HERS was 0.99 (95% confidence interval [CI], 0.81-1.22); HERS II, 1.00 (95% CI, 0.77-1.29); and overall, 0.99 (0.84-1.17). The overall RHs were similar after adjustment for potential confounders and differential use of statins between treatment groups (RH, 0.97; 95% CI, 0.82-1.14), and in analyses restricted to women who were adherent to randomized treatment assignment (RH, 0.96; 95% CI, 0.77-1.19). Lower rates of CHD events among women in the hormone group in the final years of HERS did not persist during additional years of follow-up. After 6.8 years, hormone therapy did not reduce risk of cardiovascular events in women with CHD. Postmenopausal hormone therapy should not be used to reduce risk for CHD events in women with CHD.
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              Epithelial ovarian cancer risk among women with polycystic ovary syndrome.

              To investigate the relationship between polycystic ovary syndrome (PCOS) and ovarian cancer, and to present three hypotheses regarding hormonal factors and the risk of ovarian cancer in women. Data were analyzed from a population-based, case-control study, the Cancer and Steroid Hormone Study, to test the hypotheses. Four hundred seventy-six subjects with histologically confirmed epithelial ovarian cancer were identified from eight tumor registries of the Surveillance Epidemiology and End Results program. The study included 4081 controls ascertained via random-digit telephone dialing. All subjects and controls were aged 20-54 years. Seven subjects with ovarian cancer and 24 controls reported that they had been diagnosed with PCOS before the study period. Ovarian cancer risk was found to increase 2.5-fold (95% confidence interval [CI] 1.1-5.9) among women with PCOS. This association is found to be stronger among women who never used oral contraceptives (odds ratio [OR] 10.5, 95% CI 2.5-44.2) and women who were in the first quartile of body mass index (13.3-18.5 kg/m2) at age 18 (OR 15.6, 95% CI 3.4-71.0). The data suggest that the hormonal status of women with PCOS featuring abnormal patterns of gonadotropic secretion (enhanced levels of LH) in lean women may be a mitigating factor for the observed association between PCOS and ovarian cancer. We hope that our preliminary data stimulate further investigation of the testable hypotheses.
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                Author and article information

                Journal
                Clinics
                Clinics (Sao Paulo, Brazil)
                Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo
                1807-5932
                1980-5322
                June 2008
                : 63
                : 3
                : 381-388
                Affiliations
                [I ] Histology and Cellular Biology Division, Morphology Department of UNIFESP – São Paulo/SP, Brazil
                [II ] LIM-58, Faculdade de Medicina da Universidade de São Paulo – São Paulo/SP, Brazil
                [III ] Gynecology Department, Faculdade de Medicina da Universidade Federal de São Paulo – São Paulo/SP, Brazil. jsoares415@ 123456hotmail.com
                Article
                cln63_3p0381
                10.1590/S1807-59322008000300016
                2664246
                18568250
                bb869926-75e0-4e23-8651-be9c17d1167c
                Copyright © 2008 Hospital das Clínicas da FMUSP
                History
                : 27 December 2007
                : 10 March 2008
                Categories
                Basic Research

                Medicine
                ovary,estrogens,animal model,superficial epithelium
                Medicine
                ovary, estrogens, animal model, superficial epithelium

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