RESUMO
The serum estrogen surge in the uterus triggers precisely-timed physiological and biochemical responses required establishing and maintaining pregnancy. Previous reports have shown that consumption of phytoestrogen-containing plants may disrupt the precise control of pregnancy. To evaluate the effects of phytoestrogens in the uterus, we screened for estradiol (E2)-inducible genes in immature rat uteri. We identified the gene for receptor-activity-modifying protein 2 (Ramp2), known to be a component of the adrenomedullin (ADM) receptor, as responsive to both E2 and the phytoestrogen coumestrol (Cou). We further examined the expression of ADM and ADM signaling components Ramp2, Ramp3, and CRLR in the immature rat uterus and found that both E2 and Cou regulated these genes expression. In addition, treatment with ADM increased uterine weight and edema similar to that observed after Cou treatment. Our findings indicated that the phytoestrogen caused the abnormal induction of vasoactive factors in the uterus.
Assuntos
Estradiol/análogos & derivados , Estradiol/farmacologia , Regulação da Expressão Gênica , Peptídeos/genética , Fitoestrógenos/farmacologia , Receptores de Peptídeos/genética , Útero/metabolismo , Adrenomedulina , Animais , Proteína Semelhante a Receptor de Calcitonina , Cumestrol/farmacologia , Estradiol/fisiologia , Estro/fisiologia , Feminino , Fulvestranto , Peptídeos e Proteínas de Sinalização Intracelular , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Tamanho do Órgão/efeitos dos fármacos , Peptídeos/metabolismo , RNA Mensageiro/análise , RNA Mensageiro/metabolismo , Ratos , Proteína 2 Modificadora da Atividade de Receptores , Proteína 3 Modificadora da Atividade de Receptores , Proteínas Modificadoras da Atividade de Receptores , Receptores de Adrenomedulina , Receptores da Calcitonina/genética , Receptores da Calcitonina/metabolismo , Receptores de Peptídeos/biossíntese , Útero/citologia , Útero/efeitos dos fármacosRESUMO
Phytoestrogens are assumed to affect the endocrine system of animal species similarly to other man-made endocrine disrupters and to exert their effects through estrogen receptors, specifically ER(alpha) and ERbeta. However, these molecular mechanisms are not fully understood. In this study, 19 phytochemicals were surveyed for agonist and antagonist activities of ER(alpha) and ERbeta using an ERE-luciferase reporter assay. The results showed that ferutinine is an agonist for ER(alpha) and an agonist/antagonist for ERbeta, tschimgine is an agonist for both ER(alpha) and ERbeta, and tschimganidine is an agonist for only ER(alpha). Ferutinine and tschimganidine are sesquiterpenoids, and tschimgine is a monoterpenoid derived from the Umbelliferae family. A competitive binding assay showed that ferutinine has higher binding affinities than tamoxifen for both ERs. Co-transfections of coactivators such as SRC-1, TIF2, AIB1, and TRAP220 in 293T cells and use of the luciferase assay revealed that TRAP220 failed to enhance the transcription mediated by ERbeta in the presence of ferutinine. Moreover, a GST pull-down assay showed that TRAP220 marginally bound to ERbeta ligand binding domain in the presence of ferutinine. These results suggest that the conformation of ferutinine-liganded ERbeta is difficult for TRAP220 to recognize. Taken together, this suggests that some terpenoids can modulate estrogen signaling as ER subtype-selective phytoestrogens similar to SERMs (selective estrogen receptor modulators).