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Query: UMLS:C0028754 (obesity)
 124,988 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Breast cancer, the most frequent spontaneous malignancy diagnosed in women in the Western world, is a classical model of hormone dependent malignancy. There is substantial evidence that breast cancer risk is associated with prolonged exposure to female hormones, since early onset of menarche, late menopause, hormone replacement therapy and postmenopausal obesity are associated with greater cancer incidence. Among these hormonal influences a leading role is attributed to estrogens, either of ovarian or extra-ovarian origin, as supported by the observations that breast cancer does not develop in the absence of ovaries, ovariectomy causes regression of established malignancies, and in experimental animal models estrogens can induce mammary cancer. Estrogens induce in rodents a low incidence of mammary tumors after a long latency period, and only in the presence of an intact pituitary axis, with induction of pituitary hyperplasia or adenomas and hyperprolactinemia. Chemicals, radiation, viruses and genomic alterations have all been demonstrated to have a greater tumorigenic potential in rodents. Chemical carcinogens are used to generate the most widely studied rat models; in these models hormones act as promoters or inhibitors of the neoplastic process. The incidence and type of tumors elicited, however, are strongly influenced by host factors. The tumorigenic response is maximal when the carcinogen is administered to young and virgin intact animals in which the mammary gland is undifferentiated and highly proliferating. The atrophic mammary gland of hormonally-deprived ovariectomized or hypophysectomized animals does not respond to the carcinogenic stimulus. Administration of carcinogen to pregnant, parous or hormonally treated virgin rats, on the other hand, fails to elicit a tumorigenic response, a phenomenon attributed to the higher degree of differentiation of the mammary gland induced by the hormonal stimulation of pregnancy. In women a majority of breast cancers that are initially hormone dependent are manifested during the postmenopausal period. Estradiol plays a crucial role in their development and evolution. However, it is still unclear whether estrogens are carcinogenic to the human breast. The apparent carcinogenicity of estrogens is attributed to receptor-mediated stimulation of cellular proliferation. Increased proliferation could result in turn in accumulation of genetic damage and stimulation of the synthesis of growth factors that act on the mammary epithelial cells via an autocrine or paracrine loop. Alternatively estrogens may induce cell proliferation through negative feedback by removing the effect of one or several inhibitory factors present in the serum. Multidisciplinary studies are required for the elucidation of the mechanisms responsible for the initiation of breast cancer. Understanding of such mechanisms is indispensable for developing a rational basis for its prevention and control.
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PMID:Role of hormones in mammary cancer initiation and progression. 1081 4

We hypothesized that estradiol treatment would improve vascular dysfunction commonly associated with obesity, hyperlipidemia, and insulin resistance. A sham operation or 17beta-estradiol pellet implantation was performed in male lean and obese Zucker rats. Maximal vasoconstriction (VC) to phenylephrine (PE) and potassium chloride was exaggerated in control obese rats compared with lean rats, but estradiol significantly attenuated VC in the obese rats. Estradiol reduced the PE EC50 in all groups. This effect was cyclooxygenase independent, because preincubation with indomethacin reduced VC response to PE similarly in a subset of control and estrogen-treated lean rats. Endothelium-independent vasodilation (VD) to sodium nitroprusside was similar among groups, but endothelium-dependent VD to ACh was significantly impaired in obese compared with lean rats. Estradiol improved VD in lean and obese rats by decreasing EC50 but impaired function by decreasing maximal VD. The shift in EC50 corresponded to an upregulation in nitric oxide synthase III protein expression in the aorta of the estrogen-treated obese rats. In summary, estrogen treatment improves vascular function in male insulin-resistant, obese rats, partially via an upregulation of nitric oxide synthase III protein expression. These effects are counteracted by adverse factors, such as hyperlipidemia and, potentially, a release of an endothelium-derived contractile agent.
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PMID:Estrogen has opposing effects on vascular reactivity in obese, insulin-resistant male Zucker rats. 1196 Sep 55

Patients with polycystic ovary syndrome (PCOS) usually are obese, insulin resistant and hyperinsulinemic. The known association between leptin, obesity and insulin action suggests that leptin may have a role in PCOS but this has only been addressed peripherally. This study was designed to assess the relationship between serum leptin and the anthropometric, metabolic and endocrine variables of obese (body mass index, BMI (3)30 kg/m(2)) and non-obese (BMI <30 kg/m(2)) PCOS patients. Twenty-eight PCOS patients and 24 control women subdivided into obese and non-obese groups were evaluated. Leptin, androgens, lipids, gonadotrophins and insulin-glucose response to the oral glucose tolerance test were measured by radioimmunoassay in all participants. The assays were done all in one time. The areas under the insulin curve (AUC-I) and the glycemia curve were calculated to identify patients with insulin resistance. Mean leptin levels were not significantly higher in patients with PCOS compared to the control group (21.2 +/- 10.2 vs 27.3 +/- 12.4 ng/ml). Leptin levels were found to be significantly higher in the obese subgroups both in patients with PCOS (26.9 +/- 9.3 vs 14.1 +/- 7.0 ng/ml) and in the control group (37.3 +/- 15.5 vs 12.9 +/- 5.8 ng/ml). The leptin of the PCOS group was correlated with BMI (r = 0.74; P < 0.0001) and estradiol (r = 0.48; P < 0.008) and tended to be correlated with the AUC-I (r = 0.36; P = 0.05). Of the parameters which showed a correlation with leptin in PCOS, only estradiol and probably insulinemia (AUC-I) did not show a significant correlation with BMI, suggesting that the other parameters were correlated with leptin due to their correlation with BMI. Estradiol correlated with leptin in PCOS patients regardless of their weight.
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PMID:Positive correlation of serum leptin with estradiol levels in patients with polycystic ovary syndrome. 1510 36

The case of a 62-year-old woman with severe post-menopausal hirsutism is described. Her clinical history revealed regular menstrual periods until menopause at the age of 50, hysterectomy for fibromatosis at 58 years, non-insulin dependent diabetes mellitus, hypertension, obesity, severe hirsutism, which had developed in the previous 3 years, with a deeping of the voice. Examination showed android obesity, hypertension and severe hirsutism involving the face and the trunk. Endocrine evaluation pointed out regular adrenal function, serum total and free-testosterone in the adult male range, with normal androstenedione, DHEAS and 17OHP levels. Estradiol was slightly increased and LH and FSH were inappropriately low for her post-menopausal age. Computed tomography of the abdomen showed regular adrenal glands, and a radio-labeled cholesterol scan was negative. A further pelvic transvaginal ultrasonography revealed a small cystic formation near the right ovary and a slight increase in the size of the left ovary. The patient underwent bilateral ovariectomy. Histological examination showed a lipoid cell tumor within the left ovary. Immunohistochemical studies were positive for inhibin and cytokeratin. After surgery, serum testosterone fell to normal levels, gonadotropins increased to menopausal levels, confirming that the tumor was able to produce both LH, and FSH-inhibiting factors, and hirsutism greatly improved. Periodic hormonal tests remained normal and CT of the abdomen and pelvic ultrasonography did not show alterations at a 3 years follow-up.
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PMID:[Severe postmenopausal hyperandrogenism due to an ovarian lipoid cell tumor: a case report]. 1525 55

Estrogen is considered a major regulator of adipose tissue in females. Estrogen increases circulating levels of atrial natriuretic peptide (ANP), a hormone with renal and cardiovascular effects. The aim of this study was to determine the status of the natriuretic peptide system in female follitropin-receptor knockout (FORKO) mice that could be associated with obesity and hypertension observed in these mutants. Furthermore, estradiol treatment was used to reverse alterations observed. FORKO and wild-type (WT) mice received daily injections of estradiol for 4 d. On the fifth day, blood was collected for determination of plasma ANP levels, and selected tissues were collected for determination of ANP, natriuretic peptide receptor type-A (NPR-A) and type-C (NPR-C) gene expression by RT-PCR and binding of [(125)I]ANP by autoradiography. At 5 months of age, FORKO mice were heavier and had more adipose tissue than WT mice. FORKO mice had lower plasma ANP levels and atrial ANP gene expression and higher renal and adipocyte NPR-C gene expression than WT mice. Estradiol treatment reduced weight gain and increased atrial ANP synthesis as well as decreased ANP clearance NPR-C receptors, resulting in elevation of circulating ANP level. In conclusion, this study shows that FORKO females have an impaired natriuretic peptide system, which may contribute to the susceptibility of FORKO mice to developing age-related hypertension previously shown in these animals. This study establishes a relation between estrogen, adipose tissue, and ANP, which may have important implications in menopausal women.
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PMID:Impairment of the natriuretic peptide system in follitropin receptor knockout mice and reversal by estradiol: implications for obesity-associated hypertension in menopause. 1806 89

Breast cancer (BC) is one of the most important problems of public health. Among the avoidable risk factors during a woman's life, overweight and obesity are very important ones. Furthermore they are increasing worldwide. The risk of breast cancer is traditionally linked to obesity in postmenopausal women; conversely, it is neutral or even protective in premenopausal women. Since the initiator and promoter factors for BC act over a long time, it seems unlikely that the menopausal transition may have too big an impact on the role of obesity in the magnitude of the risk. We reviewed the literature in an attempt to understand this paradox, with particular attention to the body fat distribution and its impact on insulin resistance. The association of insulin resistance and obesity with BC risk are biologically plausible and consistent. Estradiol (E2) and IGFs act as mitogens in breast cancer cells. They act together and reciprocally. However the clinical and biological methods to assess the impact of insulin resistance are not always accurate. Furthermore insulin resistance is far from being a constant feature in obesity, particularly in premenopausal women; this complicates the analysis and explains the discrepancies in large prospective trials. The most consistent clinical feature to assess risk across epidemiological studies seems to be weight gain during lifetime. Loss of weight is associated with a lower risk for postmenopausal BC compared with weight maintenance. This observation should be an encouragement for women since loss of weight may be an effective strategy for breast cancer risk reduction.
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PMID:Insulin resistance, obesity and breast cancer risk. 1848 31

Obesity, alcohol consumption, physical inactivity and postmenopausal hormone use are known modifiable risk factors for breast cancer. We aim to measure incidence rates of breast cancer for women with favorable levels on all 4 risk factors (BMI <or= 30 kg/m(2), alcohol <1 drink/week, physically active and no current hormone use) and to evaluate their associations with estrogen. The 5,054 postmenopausal women in the Copenhagen City Heart Study were asked about risk factors at baseline in 1981-3 and were followed until 2002 in the Danish Cancer Registry, with <0.1% loss to follow-up. Estradiol was measured in a subset of 1,042 women. During follow-up, 263 women developed breast cancer. Twenty-six percent of the women had a favourable risk factor profile, and their breast cancer rates were markedly lower (154 per 100,000 years) than women with 3+ risk factors (460 per 100,000 years). One, two and three risk factors were associated with hazard ratios of 1.38 (95% CI: 0.99; 1.92), 1.84 (1.26; 2.67) and 2.79 (1.59; 4.88) compared to women with a favourable profile. Each of the risk factors was associated with estrogen. In conclusion, the risk of breast cancer was markedly lower for women with a favourable risk profile than for other women and lower estrogen levels is a possible explanation.
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PMID:Low-risk factor profile, estrogen levels, and breast cancer risk among postmenopausal women. 1912 66

Menopause is one of the triggers that induce obesity. Estradiol (E2), corticotropin-releasing hormone (CRH), and hypothalamic neuronal histamine are anorexigenic substances within the hypothalamus. This study examined the interactions among E2, CRH, and histamine during the regulation of feeding behavior and obesity in rodents. Food intake was measured in rats after the treatment of E2, alpha-fluoromethyl histidine, a specific suicide inhibitor of histidine decarboxylase that depletes hypothalamic neuronal histamine, or CRH antagonist. We measured food intake and body weight in wild-type mice or mice with targeted disruption of the histamine receptors (H1-R) knockout (H1KO mice). Furthermore, we investigated CRH content and histamine turnover in the hypothalamus after the E2 treatment or ovariectomy (OVX). We used immunohistochemical staining for estrogen receptors (ERs) in the histamine neurons. The E2-induced suppression of feeding was partially attenuated in rats pre-treated with alpha-fluoromethyl histidine or CRH antagonist and in H1KO mice. E2 treatment increased CRH content and histamine turnover in the hypothalamus. OVX increased food intake and body weight, and decreased CRH content and histamine turnover in the hypothalamus. In addition, E2 replacement reversed the OVX-induced changes in food intake and body weight in wild-type mice but not in H1KO mice. Immunohistochemical analysis revealed ERs were expressed on histamine neurons and western blotting analysis and pre-absorption study confirmed the specificity of ER antiserum we used. These results indicate that CRH and hypothalamic neuronal histamine mediate the suppressive effects of E2 on feeding behavior and body weight.
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PMID:Hypothalamic neuronal histamine signaling in the estrogen deficiency-induced obesity. 1961 43

Following menopause, body fat is redistributed from peripheral to central depots. This may be linked to the age related decrease in estrogen levels. We hypothesized that estrogen supplementation could counteract this fat redistribution through tissue-specific modulation of glucocorticoid exposure. We measured fat depot masses and the expression and activity of the glucocorticoid-activating enzyme 11beta-hydroxysteroid dehydrogenase type 1 (11betaHSD1) in fat and liver of ovariectomized female rats treated with or without 17beta-estradiol. 11betaHSD1 converts inert cortisone, or 11-dehydrocorticosterone in rats into active cortisol and corticosterone. Estradiol-treated rats gained less weight and had significantly lower visceral adipose tissue weight than nontreated rats (P < 0.01); subcutaneous adipose weight was unaltered. In addition, 11betaHSD1 activity/expression was downregulated in liver and visceral, but not subcutaneous, fat of estradiol-treated rats (P < 0.001 for both). This downregulation altered the balance of 11betaHSD1 expression and activity between adipose tissue depots, with higher levels in subcutaneous than visceral adipose tissue of estradiol-treated animals (P < 0.05 for both), opposite the pattern in ovariectomized rats not treated with estradiol (P < 0.001 for mRNA expression). Thus, estrogen modulates fat distribution, at least in part, through effects on tissue-specific glucocorticoid metabolism, suggesting that estrogen replacement therapy could influence obesity related morbidity in postmenopausal women.
Obesity (Silver Spring) 2010 Mar
PMID:Estrogen reduces 11beta-hydroxysteroid dehydrogenase type 1 in liver and visceral, but not subcutaneous, adipose tissue in rats. 1976 91

Ecdysteroids are steroids found in invertebrates and plants. In mammals they have protein anabolic effects. We have recently published antiosteoporotic effects of Tinospora cordifolia (TC) extract and the search for the possible active ingredients yielded the presence of beta-Ecdysone (Ecd). Therefore, we investigated the effects of pure Ecd in ovariectomized rats on morphological changes in joint, epiphyseal cartilage and trabecular tissue. Following ovariectomy rats were fed for 1 month with Ecd containing food at a dose of 52.8 mg/day/animal. Positive and negative control animals received 17-beta Estradiol (E(2), 132 microg/day/animal) and soy free (sf) food respectively. At sacrifice, specimens consisting of upper tibiae-lower femurs and knee joint were harvested and processed for histomorphometry. The parameters measured included thickness of the joint cartilage, thickness of the whole epiphyseal growth plate and its three zones. Furthermore, the percentage of trabecular bone in the metaphysis region of tibiae was quantified. Ecd and E(2) induced a significant increase in the thickness of joint cartilage. The whole epiphyseal growth plate and its proliferative and hypertrophic zones were also increased by Ecd whereas E(2) reduced their size. The percentage of trabecular area in the metaphysis of tibia was significantly increased in Ecd and E(2) treated animals. Results provide a plausible explanation for the antiosteoporotic effects of TC. Hence, TC as well as other Ecd producing plants or pure Ecd may be of value in the prevention and treatment of osteoporosis and osteoarthritis which is of increasing importance due to aging and obesity among individuals.
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PMID:Beneficial effects of beta-Ecdysone on the joint, epiphyseal cartilage tissue and trabecular bone in ovariectomized rats. 2017 Oct 72


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