1,721,153 research outputs found
Pure estrogenic effect of benzophenone-2 (BP2) but not of bisphenol A (BPA) and dibutylphtalate (DBP) in uterus, vagina and bone
No full textContradictory results whether the endocrine disrupters (ED) benzophenone-2 (BP2), bisphenol A (BPA) and dibutylphtalate (DBP) exert estrogenic effects have been published. Selective estrogen receptor modulators (SERMs) exert estrogenic effects in some but not in all organs and ED may be SERMs. Therefore, we studied their binding properties to recombinant ERalpha and ERbeta protein and their effects in the uterus, vagina and bone of ovariectornized rats. BP2 bound to both receptor Subtypes, while BPA had a relatively high ERbeta selectivity. DBP did not bind to ERalpha but with a low affinity to ERbeta. In the uterus, only E, and BP2 increased uterine weight and the complement C3 but decreased ERbeta gene expression. Discrete effects of BPA and DBP in the uterus were found upon histological examination. In the vagina, BP2 but not BPA and DBP had clear estrogenic effects. E-2 and BP2 had antiosteoporotic effects in the metaphysis of the tibia. The serum surrogate parameters of bone metabolism, i.e. osteocalcin and the cross (rat) laps were significantly reduced by E-2 an effect shared with BP2 but not by the two other EDs. The conclusion: BP2 acts as ERalpha and ERbeta agonist mimicking effects of E-2,, while the effects of BPalpha and DBP are not pure estrogenic. (C) 2004 Elsevier Ireland Ltd. All rights reserved
Estrogen receptor beta: Tissue distribution and the still largely enigmatic physiological function
No full textIn 1996, the molecular biology of E2 had to be reevaluated: in an effort to identify novel nuclear receptors or unknown isoforms of existing receptors Kuiper and colleague described the expression of a novel subtype of the estrogen receptor (ER) in rat prostate and ovary. Upon this pioneering discovery the already known ER was renamed ER alpha while the newly described ER was termed ER beta. In this review an attempt is made to summarize the current knowledge regarding the expression and function of ER beta in selected reproductive and non-reproductive organs under physiological conditions. The data suggest that ER beta may be considered as a dominant-negative regulator of ERa modulating transcriptional responses to estrogens. The ratio of ER alpha vs. beta. within a cell may determine the cell sensitivity to estrogens and its biological responses to the hormone. Conclusion: It is not the ligand, it is the multiplicity of receptors which determines the plethora of estrogen actions. This article is part of a Special Issue entitled 'Phytoestrogens'. (C) 2013 Elsevier Ltd. All rights reserved
Effects of Estradiol Benzoate, Raloxifen and an Ethanolic Extract of Cimicifuga racemosa in Nonclassical Estrogen Regulated Organs of Ovariectomized Rats
No full textThe special extract of Cimicifuga racemosa (CR) BNO 1055 was shown to have bone protective effects without exerting estrogenic effects in the uterus or mammary gland. Whether the effects of CR BNO 1055 would be exerted in other organs that also express estrogen receptors (ERs) but in which the effects of estrogens and of the selective estrogen receptor modulator raloxifen (Ral) were not thoroughly studied was therefore investigated in the present contribution. Rats were ovariectomized (ovx) and their food immediately substituted with estradiol benzoate (EB), Ral or 2 doses of CR BNO 1055 for 3 months. Expressions of estrogen receptor alpha (ER alpha), estrogen receptor beta (ER beta) and of insulin-like growth factor-1 (IGF-1) genes were determined in the vagina, liver, thyroid gland, lung, spleen, colon and kidney by means of quantitative RT-PCRs. Body weights in all treatment groups were significantly reduced and uterine weights in the EB treated animals were largely and in the Ral treated animals slightly but significantly increased. CR BNO 1055 was without effects in the uterus. We tested 3 genes: ER alpha gene expression was significantly reduced in the vagina, liver and kidney and remained unaffected in all other organs with the exception of the thyroid gland where ERa gene expression was stimulated by EB, Ral had - if any similar effects in these organs. The CR extract BNO 1055 was devoid of any effect on ER alpha gene ex-pression. ER beta gene expression was suppressed in the vagina and colon by EB and this effect was shared by Ral in the colon. In the thyroid, EB and Ral stimulated ER beta gene expression. Expression of IGF-1 gene was stimulated by EB and CR BNO 1055 in the vagina and kidney and inhibited by EB and Ral in the liver. No effects were observed by CR BNO 1055 in these organs. The effects of Ral, if occurring, were similar to those of EB while CR BNO 1055 was ineffective in all organs but the vagina. In the colon, reduced ER beta gene activity may augment ER alpha mediated effects. in all other organs the effects of ER await further investigation. The CR BNO 1055 did not show any activity pattern which Would be similar to the pattern observed under EB or Ral. Therefore the observed effects of CR BNO 1055 in these organs are most likely not estrogenic in nature.EU Network of Excellence CASCADE [Food-CT- 2004-506319
Mechanisms of action of antiosteoporotic effects of a special Cimicifuga racemosa (CR) extract: inhibition of the RANK-RANKL-osteoprotegerin triad
No full textMechanisms of action of antiosteoporotic effects of a special Cimicifuga racemosa (CR) extract: Inhibition of the RANK-RANKL-Osteoprotegerin triad
No full textThe influence of equol on the hypothalamic-pituitary-thyroid axis and hepatic lipid metabolic parameters in adult male rats
No full textAims: Equol, the principal active metabolite of soy-derived phytoestrogen daidzein, has well-known estrogenic actions. Results of several studies indicate that equol may also have anti-androgenic activities. However, mechanisms of action of equol on hypothalamic-pituitary-thyroid axis (HPTA) and hepatic lipid metabolism in adult male rats have not been determined yet. Main methods: Equol at two doses of 100 and 250 mg/kg body weight (BW)/day was orally gavaged for 5 days to groups of 4-month-old male rats. As a positive anti-androgenic control group, animals received 100 mg of pure anti-androgenic drug flutamide/kg BW/day. Circulating concentrations of thyroid hormones and lipids, and expression levels of genes underlying HPTA function were determined by radioimmunoassay and TaqMan (R) real-time reverse transcription polymerase chain reaction, respectively. Key findings: Flutamide significantly decreased relative prostate weight, whereas equol did not. Both equol and flutamide caused a significant increase in relative liver weights, and decreases in plasma levels of total tetraiodothyronine (T4) and triiodothyronine (T3), whereas free T4 and T3 concentrations were not reduced. Equol caused the marked down-regulation of hypothalamic thyrotropin-releasing hormone mRNA expression, whereas flutamide did not. Equol as well as flutamide significantly down-regulated the expression levels of pituitary thyrotropin beta-subunit mRNA, without altering thyrotropin secretion. Equol caused reductions in plasma levels of total cholesterol, high- and low-density lipoproteins and triglycerides, whereas flutamide exerted opposite effects. Significance: This is the first study to reveal that in male rats equol did not affect HPTA function and liver lipid metabolism through the anti-androgenic pathway, however, the intrinsic estrogenic actions of equol were observed. (C) 2015 Elsevier Inc. All rights reserved
Effects of the natural endocrine disruptor equol on the pituitary function in adult male rats
No full textEquol (EQ), a potent biologically active metabolite of the soy isoflavone daidzein, interacts with estrogen receptors (ERs), however, as suggested recently, EQ may also exert anti-androgenic actions in androgen regulated tissues like prostate and seminal vesicles in adult male rats. However, data regarding a putative anti-androgenic activity of EQ on pituitary function in male individuals are still lacking. Therefore, we investigated the effects of EQ on androgen- and estrogen-regulated gene expressions in the pituitary and circulating luteinizing hormone (LH) and prolactin (PRL) levels in adult male rats. 3-Month-old male Sprague-Dawley rats (n=12 per group) were treated by gavage for 5 days with either EQ(100 and 250 mg/kg BW/day) or vehicle olive oil (1 ml/rat/day). As reference compound, the pure anti-androgenic drug flutamide (FLUT) was employed at a dose of 100 mg/kg BW/day. At day 5, animals were sacrificed. Levels of pituitary hormones and gene expression were measured by radioimmunoassays and quantitative TaqMan (R) real-time reverse transcription polymerase chain reaction, respectively. The present findings revealed that the pituitary mechanisms involved in the effects of EQ and FLUT were different due to the opposite changes in the mRNA expression levels of estrogen receptor subtype alpha (ER alpha)-, truncated estrogen receptor product-1 (TERP-1)- and -2 (TERP-2)-, gonadotropin releasing hormone receptor (GnRH receptor)-, beta-subunit of LH (LH beta)-, and gonadotropin alpha subunit (alpha-subunit) genes. EQ displayed typical ER-agonistic actions as shown by the significant increases in ER alpha-, TERP-1/-2 mRNA expressions and serum PRL levels along with the significant reduction in serum LH levels, whereas FLUT exerted opposite effects on gonadotropin secretion and expression. Taken together, our findings are the first in vivo data that upon sub-acute oral exposure of EQ show an estrogenic effect on reproductive endocrine activity of the pituitary in adult male rats. However, EQ did not exert anti-androgenic effects on male rat pituitary function as observed at the levels of mRNA expression of androgen- and estrogen-regulated genes and circulating pituitary hormones. (C) 2012 Elsevier Ireland Ltd. All rights reserved
Mechanisms of action of antiosteoporotic effects of a special Cimicifuga racemosa (CR) extract: Inhibition of the RANK-RANKL-Osteoprotegerin triad
No full text- …
