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Kenneth S Korach

Publications and source records attributed to Kenneth S Korach.

At least 19 recordsLinked to original sources

Multiple oestradiol functions inhibit ferroptosis and acute kidney injury.

Acute tubular necrosis mediates acute kidney injury (AKI) and nephron loss1, the hallmark of end-stage renal disease2-4. For decades, it has been known that female kidneys are less sensitive to AKI5,6. Acute tubular necrosis involves dynamic cell death propagation by ferroptosis along the tubular compartment7,8. Here we demonstrate abrogated ferroptotic cell death propagation in female kidney tubules. 17β-oestradiol establishes an anti-ferroptotic state through non-genomic and genomic mechanisms. These include the potent direct inhibition of ferroptosis by hydroxyoestradiol derivatives, which function as radical trapping antioxidants, are present at high concentrations in kidney tubules and, when exogenously applied, protect male mice from AKI. In cells, the oxidized hydroxyoestradiols are recycled by FSP19,10, but FSP1-deficient female mice were not sensitive to AKI. At the genomic level, female ESR1-deficient kidney tubules partially lose their anti-ferroptotic capacity, similar to ovariectomized mice. While ESR1 promotes the anti-ferroptotic hydropersulfide system, male tubules express pro-ferroptotic proteins of the ether lipid pathway which are suppressed by ESR1 in female tissues until menopause. In summary, we identified non-genomic and genomic mechanisms that collectively explain ferroptosis resistance in female tubules and may function as therapeutic targets for male and postmenopausal female individuals.

Ferroptosis↗

Estrogen receptor-alpha mediates an intraovarian negative feedback loop on thecal cell steroidogenesis via modulation of Cyp17a1 (cytochrome P450, steroid 17alpha-hydroxylase/17,20 lyase) expression.

Excess androgen synthesis by thecal cells is invariably detrimental to preovulatory follicles in the ovary and is considered a fundamental characteristic of polycystic ovary syndrome in women. Investigators have long postulated that granulosa cell-derived estrogens modulate thecal cell steroidogenesis via a short negative-feedback loop within the follicle. To test this hypothesis, we assessed the steroidogenic capacity of individual wild-type (WT) and estrogen receptor-alpha (ER alpha)-null follicles when cultured in vitro under comparable conditions. Late-stage ER alpha-null follicles exhibited markedly increased expression of the thecal cell enzyme CYP17A1 and secreted much greater amounts of its end product, androstenedione. This phenotype was reproduced in WT follicles when exposed to an aromatase inhibitor or ER-antagonist, and prevented when the former treatment was supplemented with an ER alpha-specific agonist. ER alpha-null follicles also exhibited increased testosterone synthesis due to ectopic expression of hydroxysteroid (17beta) dehydrogenase type 3 (HSD17B3), a testis-specific androgenic enzyme. These data indicate that ER alpha functions within thecal cells to negatively modulate the capacity for androgen synthesis by repressing Cyp17a1 expression, and the biological activity of androgens produced by inhibiting Hsd17b3 expression. Hence, these findings provide novel evidence of an intraovarian ER alpha function that may be critical to the latter stages of folliculogenesis and overall ovarian function.

Androgens↗

Spontaneous airway hyperresponsiveness in estrogen receptor-alpha-deficient mice.

RATIONALE: Airway hyperresponsiveness is a critical feature of asthma. Substantial epidemiologic evidence supports a role for female sex hormones in modulating lung function and airway hyperresponsiveness in humans. OBJECTIVES: To examine the role of estrogen receptors in modulating lung function and airway responsiveness using estrogen receptor-deficient mice. METHODS: Lung function was assessed by a combination of whole-body barometric plethysmography, invasive measurement of airway resistance, and isometric force measurements in isolated bronchial rings. M2 muscarinic receptor expression was assessed by Western blotting, and function was assessed by electrical field stimulation of tracheas in the presence/absence of gallamine. Allergic airway disease was examined after ovalbumin sensitization and exposure. MEASUREMENTS AND MAIN RESULTS: Estrogen receptor-alpha knockout mice exhibit a variety of lung function abnormalities and have enhanced airway responsiveness to inhaled methacholine and serotonin under basal conditions. This is associated with reduced M2 muscarinic receptor expression and function in the lungs. Absence of estrogen receptor-alpha also leads to increased airway responsiveness without increased inflammation after allergen sensitization and challenge. CONCLUSIONS: These data suggest that estrogen receptor-alpha is a critical regulator of airway hyperresponsiveness in mice.

Acetylcholine↗

Definition of estrogen receptor pathway critical for estrogen positive feedback to gonadotropin-releasing hormone neurons and fertility.

The mechanisms through which estrogen regulates gonadotropin-releasing hormone (GnRH) neurons to control mammalian ovulation are unknown. We found that estrogen positive feedback to generate the preovulatory gonadotropin surge was normal in estrogen receptor beta knockout (ERbeta) mutant mice, but absent in ERalpha mutant mice. An ERalpha-selective compound was sufficient to generate positive feedback in wild-type mice. As GnRH neurons do not express ERalpha, estrogen positive feedback upon GnRH neurons must be indirect in nature. To establish the cell type responsible, we generated a neuron-specific ERalpha mutant mouse line. These mice failed to exhibit estrogen positive feedback, demonstrating that neurons expressing ERalpha are critical. We then used a GnRH neuron-specific Pseudorabies virus (PRV) tracing approach to show that the ERalpha-expressing neurons innervating GnRH neurons are located within rostral periventricular regions of the hypothalamus. These studies demonstrate that ovulation is driven by estrogen actions upon ERalpha-expressing neuronal afferents to GnRH neurons.

Animals↗

Abolition of sex-dependent effects of prenatal exposure to diethylstilbestrol on emotional behavior in estrogen receptor-alpha knockout mice.

To investigate the contribution of estrogen receptor-alpha in the effects of prenatal exposure to diethylstilbestrol on emotionality, estrogen receptor-alpha knockout heterozygous pregnant mice were orally given 0.1 microg/animal of diethylstilbestrol from gestational day 11 to 17. Emotional behavior of the offspring was assessed at 5 weeks in light-dark transition tests. Time spent in the light area was significantly decreased (i.e. decrease of emotionality) by diethylstilbestrol exposure in wild-type female mice, whereas in wild-type male mice this measurement tended to be increased (i.e. increase of emotionality) by diethylstilbestrol treatment. These sex-dependent effects of diethylstilbestrol were completely abolished in estrogen receptor-alpha knockout mice. These results suggest that the sex-dependent effects of diethylstilbestrol on emotionality are mainly produced by its action on estrogen receptor-alpha.

Animals↗

Estrogen-induced proliferation of uterine epithelial cells is independent of estrogen receptor alpha binding to classical estrogen response elements.

Acting via the estrogen receptor (ER), estradiol exerts pleomorphic effects on the uterus, producing cyclical waves of cellular proliferation and differentiation in preparation for embryo implantation. In the classical pathway, the ER binds directly to an estrogen response element to activate or repress gene expression. However, emerging evidence supports the existence of nonclassical pathways in which the activated ER alters gene expression through protein-protein tethering with transcription factors such as c-Fos/c-Jun B (AP-1) and Sp1. In this report, we examined the relative roles of classical and nonclassical ER signaling in vivo by comparing the estrogen-dependent uterine response in mice that express wild-type ERalpha, a mutant ERalpha (E207A/G208A) that selectively lacks ERE binding, or ERalpha null. In the compound heterozygote (AA/-) female, the nonclassical allele (AA) was insufficient to mediate an acute uterotrophic response to 17beta-estradiol (E2). The uterine epithelial proliferative response to E2 and 4-hydroxytamoxifen was retained in the AA/-females, and uterine luminal epithelial height increased commensurate with the extent of ERalpha signaling. This proliferative response was confirmed by 5-bromo-2'-deoxyuridine incorporation. Microarray experiments identified cyclin-dependent kinase inhibitor 1A as a nonclassical pathway-responsive gene, and transient expression experiments using the cyclin-dependent kinase inhibitor 1A promoter confirmed transcriptional responses to the ERalpha (E207A/G208A) mutant. These results indicate that nonclassical ERalpha signaling is sufficient to restore luminal epithelial proliferation but not other estrogen-responsive events, such as fluid accumulation and hyperemia. We conclude that nonclassical pathway signaling via ERalpha plays a critical physiologic role in the uterine response to estrogen.

Animals↗

Estrogens protect pancreatic beta-cells from apoptosis and prevent insulin-deficient diabetes mellitus in mice.

In diabetes, the death of insulin-producing beta-cells by apoptosis leads to insulin deficiency. The lower prevalence of diabetes in females suggests that female sex steroids protect from beta-cell injury. Consistent with this hypothesis, 17beta-estradiol (estradiol) manifests antidiabetic actions in humans and rodents. In addition, estradiol has antiapoptotic actions in cells that are mediated by the estrogen receptor-a (ERalpha), raising the prospect that estradiol antidiabetic function may be due, in part, to a protection of beta-cell apoptosis via ERalpha. To address this question, we have used mice that were rendered estradiol-deficient or estradiol-resistant by targeted disruption of aromatase (ArKO) or ERalpha (alphaERKO) respectively. We show here that in both genders, ArKO(-/-) mice are vulnerable to beta-cell apoptosis and prone to insulin-deficient diabetes after exposure to acute oxidative stress with streptozotocin. In these mice, estradiol treatment rescues streptozotocin-induced beta-cell apoptosis, helps sustain insulin production, and prevents diabetes. In vitro, in mouse pancreatic islets and beta-cells exposed to oxidative stress, estradiol prevents apoptosis and protects insulin secretion. Estradiol protection is partially lost in beta-cells and islets treated with an ERalpha antagonist and in alphaERKO islets. Accordingly, alphaERKO mice are no longer protected by estradiol and display a gender nonspecific susceptibility to oxidative injury, precipitating beta-cell apoptosis and insulin-deficient diabetes. Finally, the predisposition to insulin deficiency can be mimicked in WT mice by pharmacological inhibition of ERalpha by using the antagonist tamoxifen. This study demonstrates that estradiol, acting, at least in part, through ERalpha, protects beta-cells from oxidative injury and prevents diabetes in mice of both genders.

Animals↗

A G-protein-coupled estrogen receptor is involved in hypothalamic control of energy homeostasis.

Estrogens are involved in the hypothalamic control of multiple homeostatic functions including reproduction, stress responses, energy metabolism, sleep cycles, temperature regulation, and motivated behaviors. The critical role of 17beta-estradiol (E2) is evident in hypoestrogenic states (e.g., postmenopause) in which many of these functions go awry. The actions of E2 in the brain have been attributed to the activation of estrogen receptors alpha and beta through nuclear, cytoplasmic, or membrane actions. However, we have identified a putative membrane-associated estrogen receptor that is coupled to desensitization of GABAB and mu-opioid receptors in guinea pig and mouse hypothalamic proopiomelanocortin neurons. We have synthesized a new nonsteroidal compound, STX, which selectively targets the Galphaq-coupled phospholipase C-protein kinase C-protein kinase A pathway, and have established that STX is more potent than E2 in mediating this desensitization in an ICI 182, 780-sensitive manner in both guinea pig and mouse neurons. Both E2 and STX were fully efficacious in estrogen receptor alpha,beta knock-out mice. Moreover, in vivo treatment with STX, similar to E2, attenuated the weight gain in hypoestrogenic female guinea pigs. Therefore, this membrane-delimited signaling pathway plays a critical role in the control of energy homeostasis and may provide a novel therapeutic target for treatment of postmenopausal symptoms and eating disorders in females.

Animals↗

Endocrine-disrupting chemicals use distinct mechanisms of action to modulate endocrine system function.

The term endocrine-disrupting chemicals is used to define a structurally diverse class of synthetic and natural compounds that possess the ability to alter various components of the endocrine system and potentially induce adverse health effects in exposed individuals and populations. Research on these compounds has revealed that they use a variety of both nuclear receptor-mediated and non-receptor-mediated mechanisms to modulate different components of the endocrine system. This review will describe in vitro and in vivo studies that highlight the spectrum of unique mechanisms of action and biological effects of four endocrine-disrupting chemicals--diethylstilbestrol, genistein, di(n-butyl)phthalate, and methoxyacetic acid--to illustrate the diverse and complex nature of this class of compounds.

Acetates↗

The intraovarian actions of estrogen receptor-alpha are necessary to repress the formation of morphological and functional Leydig-like cells in the female gonad.

The predisposition of the testis and ovary to primarily synthesize testosterone (T) and estradiol (E2), respectively, is due to gonadal-specific cell types that differentially express the various hydroxysteroid (17beta) dehydrogenase (HSD17B) isoforms. In testes, Leydig cells rely on LH stimulation to maintain expression of the type 3 (HSD17B3) isoform, which specifically converts androstenedione to T. In ovaries, thecal interstitial (TI) cells also rely on LH to induce androgen synthesis but lack HSD17B3 and therefore secrete androgens of low biological activity. Therefore, thecal cells may possess a mechanism to repress the Leydig cell phenotype and HSD17B3 expression. E2 is known to inhibit experimentally Leydig cell function and proliferation. In the current study, we provide evidence that E2 prevents the development of functional Leydig-like cells in the murine ovary and that this action is mediated by estrogen receptor (ER) alpha. ERalpha-null (alphaERKO) female mice exhibit testis-like levels of Hsd17b3 expression in the ovaries and male-like levels of plasma T. Herein, we demonstrate that: 1) Hsd17b3 expression in alphaERKO ovaries is a primary effect of the loss of intraovarian ERalpha actions; 2) alphaERKO ovarian cells produce substantial levels of T in vitro, and this is blocked by a HSD17B3-specific inhibitor; 3) Hsd17b3 expression in alphaERKO ovaries is LH regulated and localized to the secondary interstitial (SI)/TI cells; and 4) alphaERKO SI/TI cells possess Leydig-like ultrastructural features. These data indicate that intraovarian ERalpha actions are required to repress Hsd17b3 expression in the ovary and may be important to maintaining a female phenotype in SI/TI cells.

17-Hydroxysteroid Dehydrogenases↗

Estrogen induces estrogen receptor alpha-dependent cAMP response element-binding protein phosphorylation via mitogen activated protein kinase pathway in basal forebrain cholinergic neurons in vivo.

In addition to classical genomic mechanisms, estrogen also exerts nonclassical effects via a signal transduction system on neurons. To study whether estrogen has a nonclassical effect on basal forebrain cholinergic system, we measured the intensity of cAMP response element-binding protein (CREB) phosphorylation (pCREB) in cholinergic neurons after administration of 17beta-estradiol to ovariectomized (OVX) mice. A significant time-dependent increase in the number of pCREB-positive cholinergic cells was detected after estrogen administration in the medial septum-diagonal band (MS-DB) and the substantia innominata (SI). The increase was first observed 15 min after estrogen administration. The role of classical estrogen receptors (ERs) was evaluated using ER knock-out mice in vivo. The estrogen-induced CREB phosphorylation in cholinergic neurons was present in ERbeta knock-out mice but completely absent in ERalpha knock-out mice in MS-DB and SI. A series of in vitro studies demonstrated that estrogen acted directly on cholinergic neurons. Selective blockade of the mitogen activated protein kinase (MAPK) pathway in vivo completely prevented estrogen-induced CREB phosphorylation in cholinergic neurons in MS-DB and SI. In contrast, blockade of protein kinase A (PKA) was effective only in SI. Finally, studies in intact female mice revealed levels of CREB phosphorylation within cholinergic neurons that were similar to those of estrogen-treated OVX mice. These observations demonstrate an ERalpha-mediated nonclassical effect of estrogen on the cholinergic neurons and that these actions are present under physiological conditions. They also reveal the role of MAPK and PKA-MAPK pathway activation in nonclassical estrogen signaling in the basal forebrain cholinergic neurons in vivo.

Animals↗

Estrogen receptor alpha mediates 17alpha-ethynylestradiol causing hepatotoxicity.

Estrogens are known to cause hepatotoxicity such as intrahepatic cholestasis in susceptible women during pregnancy, after administration of oral contraceptives, or during postmenopausal replacement therapy. Enterohepatic nuclear receptors including farnesoid X receptor (FXR), pregnane X receptor (PXR), and constitutive active/androstane receptor (CAR) are important in maintaining bile acid homeostasis and protecting the liver from bile acid toxicity. However, no nuclear receptor has been implicated in the mechanism for estrogen-induced hepatotoxicity. Here Era(-/-), Erb(-/-), Fxr(-/-), Pxr(-/-), and Car(-/-) mice were employed to show that Era(-/-) mice were resistant to synthetic estrogen 17alpha-ethynylestradiol (EE2)-induced hepatotoxicity as indicated by the fact that the EE2-treated Era(-/-) mice developed none of the hepatotoxic phenotypes such as hepatomegaly, elevation in serum bile acids, increase of alkaline phosphatase activity, liver degeneration, and inflammation. Upon EE2 treatment, estrogen receptor alpha (ERalpha) repressed the expression of bile acid and cholesterol transporters (bile salt export pump (BSEP), Na(+)/taurocholate cotransporting polypeptide (NTCP), OATP1, OATP2, ABCG5, and ABCG8) in the liver. Consistently, biliary secretions of both bile acids and cholesterol were markedly decreased in EE2-treated wild-type mice but not in the EE2-treated Era(-/-) mice. In addition, ERalpha up-regulated the expression of CYP7B1 and down-regulated the CYP7A1 and CYP8B1, shifting bile acid synthesis toward the acidic pathway to increase the serum level of beta-muricholic acid. ERbeta, FXR, PXR, and CAR were not involved in regulating the expression of bile acid transporter and biosynthesis enzyme genes following EE2 exposure. Taken together, these results suggest that ERalpha-mediated repression of hepatic transporters and alterations of bile acid biosynthesis may contribute to development of the EE2-induced hepatotoxicity.

Animals↗

Estren behaves as a weak estrogen rather than a nongenomic selective activator in the mouse uterus.

A proposed membrane-mediated mechanism of rapid nongenomic response to estrogen has been the intense focus of recent research. Estren, a synthetic steroid, is reported to act selectively through a rapid membrane-mediated pathway, rather than through the classical nuclear estrogen receptor (ER)-mediated pathway, to maintain bone density in ovariectomized mice without uterotropic effects. To evaluate the mechanism and physiological effects of estren, we studied responses in adult ovariectomized mice. In a 3-d uterine bioassay, we found that 300 microg estren significantly increased uterine weight; in comparison, a more maximal response was seen with 1 mug estradiol (E2). The estren response was partly ERalpha independent, because ERalpha knockout (alphaERKO) uteri also exhibited a more moderate weight increase. Estren induced epithelial cell proliferation in wild-type, but not alphaERKO, mice, indicating ERalpha dependence of the epithelial growth response. Examination of estren-regulated uterine genes by microarray indicated that early (2 h) changes in gene expression are similar to the early responses to E2. These gene responses are ERalpha dependent, because they are not seen in alphaERKO mice. Later estren-induced changes in gene expression (24 h) are blunted compared with those seen 24 h after E2. In contrast to early genes, these later estren responses are independent of ERalpha, because the alphaERKO shows a similar response to estren at 24 h. We found that E2 or estren treatments lead to depletion of ERalpha in the uterine cytosol fraction and accumulation in the nuclear fraction within 30-60 min, consistent with the ability of estren to regulate genes through a nuclear ERalpha rather than a nongenomic mechanism. Interestingly, estren, but not E2, induces accumulation of androgen receptor (AR) in the nuclear fraction of both wild-type and alphaERKO samples, suggesting that AR might be involved in the later ERalpha-independent genomic responses to estren. In conclusion, our studies suggest that estren is weakly estrogenic in the mouse uterus and might induce nuclear ERalpha- and AR-mediated responses. Given its activity in our uterine model, the use of estren as a bone-selective clinical compound needs to be reconsidered.

Animals↗

Estrogen receptor-beta gene disruption potentiates estrogen-inducible aggression but not sexual behaviour in male mice.

Aggressive behaviour of gonadally intact male mice is increased by estrogen receptor (ER)-beta gene disruption, whereas sexual behaviour remains unchanged. The elevated aggression levels following ER-beta gene disruption is pronounced during repeated aggression tests in young animals and the first aggression test in adults. In the present study, the roles of ER-beta activation in the regulation of aggressive and sexual behaviour were investigated in gonadectomized ER-beta knockout (betaERKO) and wild-type (WT) male mice treated with various doses of estrogen. Overall, estradiol benzoate (EB) treatment induced higher levels of aggression in betaERKO mice than in WT mice. In WT mice, the levels of aggression induced by EB were highest in the lowest-dose (2.5 microg/day) group and gradually decreased in higher-dosage groups. On the other hand, equally high levels of aggressive behaviour were induced by all three doses of EB in betaERKO mice. A marked genotype difference in dose responses is inferred, such that the ER-alpha-mediated facilitatory action of estrogen is more pronounced at lower and physiological doses and the ER-beta-mediated inhibitory action is only unveiled at higher doses of estrogen. In contrast to aggression, the levels of sexual behaviour induced by EB were not different between betaERKO and WT at either dose of EB (2.5 and 12.5 microg/day) examined. These findings support the notion that ER-beta activation may exert an attenuating action on male aggression induced by estrogen through ER-alpha-mediated brain mechanisms, whereas its effect on male sexual behaviour is relatively small.

Aggression↗

Estrogen receptors and human disease.

Estrogens influence many physiological processes in mammals, including but not limited to reproduction, cardiovascular health, bone integrity, cognition, and behavior. Given this widespread role for estrogen in human physiology, it is not surprising that estrogen is also implicated in the development or progression of numerous diseases, which include but are not limited to various types of cancer (breast, ovarian, colorectal, prostate, endometrial), osteoporosis, neurodegenerative diseases, cardiovascular disease, insulin resistance, lupus erythematosus, endometriosis, and obesity. In many of these diseases, estrogen mediates its effects through the estrogen receptor (ER), which serves as the basis for many therapeutic interventions. This Review will describe diseases in which estrogen, through the ER, plays a role in the development or severity of disease.

Animals↗

The bi-modal effects of estradiol on gonadotropin synthesis and secretion in female mice are dependent on estrogen receptor-alpha.

Depending on the estrous/menstrual cycle stage in females, ovarian-derived estradiol (E(2)) exerts either a negative or a positive effect on the hypothalamic-pituitary axis to regulate the synthesis and secretion of pituitary gonadotropins, LH, and FSH. To study the role of estrogen receptor-alpha (ERalpha) mediating these effects, we assessed the relevant parameters in adult wild-type (WT) and ERalpha-null (alphaERKO) female mice in vivo and in primary pituitary cell cultures. The alphaERKO mice exhibited significantly higher plasma and pituitary LH levels relative to WT females despite possessing markedly high levels of circulating E(2). In contrast, hypothalamic GnRH content and circulating FSH levels were comparable between genotypes. Ovariectomy led to increased plasma LH in WT females but no further increase in alphaERKO females, while plasma FSH levels increased in both genotypes. E(2) treatment suppressed the high plasma LH and pituitary Lhb mRNA expression in ovariectomized WT females but had no effect in alphaERKO. In contrast, E(2) treatments only partially suppressed plasma FSH in ovariectomized WT females, but this too was lacking in alphaERKO females. Therefore, negative feedback on FSH is partially E(2)/ERalpha mediated but more dependent on ovarian-derived inhibin, which was increased threefold above normal in alphaERKO females. Together, these data indicate that E(2)-mediated negative feedback is dependent on functional ERalpha and acts to primarily regulate LH synthesis and secretion. Studies in primary cultures of pituitary cells from WT females revealed that E(2) did not suppress basal or GnRH-induced LH secretion but instead enhanced the latter response, indicating that the positive influence of E(2) on gonadotropin secretion may occur at the level of the pituitary. Once again this effect was lacking in alphaERKO gonadotropes in culture. These data indicate that the aspects of negative and positive effects of E(2) on gonadotropin secretion are ERalpha dependent and occur at the level of the hypothalamus and pituitary respectively.

Animals↗

Upregulation of estrogen receptor expression in the uterus of ovariectomized B6C3F1 mice and Ishikawa cells treated with bromoethane.

In a 2-year NTP bioassay, Bromoethane (BE) was found to induce endometrial neoplasms in the uterus of B6C3F1 mice [; ]. In women, hormonal influences, such as "unopposed" estrogenic stimulus, have been implicated as important etiologic factors in uterine cancer. BE, however, does not affect the serum concentrations of sex hormones in female B6C3F1 mice [] and the mechanism of BE-induced uterine carcinogenesis still remains unclear. In the present study, we examined the estrogenic effects of BE on the uterus of ovariectomized B6C3F1 mice and on Ishikawa cells. Groups of 6 mice were given daily s.c. injections of 0, 100, 500 or 1000 mg BE/kg for 3 consecutive days. Mice treated with 17beta-estradiol served as positive controls. Mice were necropsied 24 h after the final injection, and uteri were weighed and examined histologically and immunohistochemically along with the vagina. Changes observed in the estrogen-treated mice included increased uterine weights, edema and inflammation of the endometrium, increased epithelial layers of the uterine and vaginal lumens and keratinization of the vaginal epithelium. In the BE-treated mice, no such changes occurred; however, immunohistochemical staining of the uterus revealed a significant increase in immunoexpression of the estrogen receptor alpha (ERalpha) in the two higher dose groups. Analysis of mRNA also showed slightly increased uterine ERalpha expression in these groups. Upregulated expression of ERalpha was confirmed in BE-treated Ishikawa cells, in which Western blotting analyses identified an intense signal at approximately 66 kDa, which is consistent with ERalpha. These data suggest that upregulated expression of ERalpha may be important in the induction of endometrial neoplasms in BE-treated mice.

Animals↗