RESUMO
Hippocampal neuropathology is a recognized feature of the spontaneously hypertensive rat (SHR). The hippocampal alterations associate with cognitive impairment. We have shown that hippocampal abnormalities are reversed by 17ß-estradiol, a steroid binding to intracellular receptors (estrogen receptor α and ß subtypes) or the membrane-located G-protein coupled estradiol receptor. Genistein (GEN) is a neuroprotective phytoestrogen which binds to estrogen receptor ß and G-protein coupled estradiol receptor. Here, we investigated whether GEN neuroprotection extends to SHR. For this purpose, we treated 5-month-old SHR for 2 weeks with 10 mg kg-1 daily s.c injections of GEN. We analyzed the expression of doublecortin+ neuronal progenitors, glial fibrillary acidic protein+ astrocytes and ionized calcium-binding adapter molecule 1+ microglia in the CA1 region and dentate gyrus of the hippocampus using immunocytochemistry, whereas a quantitative real-time polymerase chain reaction was used to measure the expression of pro- and anti-inflammatory factors tumor necrosis factor α, cyclooxygenase-2 and transforming growth factor ß. We also evaluated hippocampal dependent memory using the novel object recognition test. The results showed a decreased number of doublecortin+ neural progenitors in the dentate gyrus of SHR that was reversed with GEN. The number of glial fibrillary acidic protein+ astrocytes in the dentate gyrus and CA1 was increased in SHR but significantly decreased by GEN treatment. Additionally, GEN shifted microglial morphology from the predominantly activated phenotype present in SHR, to the more surveillance phenotype found in normotensive rats. Furthermore, treatment with GEN decreased the mRNA of the pro-inflammatory factors tumor necrosis factor α and cyclooxygenase-2 and increased the mRNA of the anti-inflammatory factor transforming growth factor ß. Discrimination index in the novel object recognition test was decreased in SHR and treatment with GEN increased this parameter. Our results indicate important neuroprotective effects of GEN at the neurochemical and behavioral level in SHR. Our data open an interesting possibility for proposing this phytoestrogen as an alternative therapy in hypertensive encephalopathy.
Assuntos
Genisteína , Fitoestrógenos , Ratos , Animais , Ratos Endogâmicos SHR , Genisteína/farmacologia , Fitoestrógenos/farmacologia , Fitoestrógenos/metabolismo , Proteína Glial Fibrilar Ácida/metabolismo , Receptores de Estradiol/metabolismo , Fator de Necrose Tumoral alfa/metabolismo , Ciclo-Oxigenase 2/metabolismo , Ratos Endogâmicos WKY , Hipocampo/metabolismo , Fator de Crescimento Transformador beta/metabolismo , Proteínas do Domínio Duplacortina , RNA Mensageiro/metabolismoRESUMO
The relationship between menopause and the development of metabolic diseases is well established. In postmenopause women, there is an expansion of visceral white adipose tissue (WATv), which highly contributes to the rise of circulating lipids. Meanwhile, muscle glucose uptake decreases and hepatic glucose production increases. Consequently, in the pancreas, lipotoxicity and glycotoxicity lead to deficient insulin production. These factors initiate an energy imbalance and enhance the probability of developing cardiovascular and metabolic diseases. Although the activation of estradiol receptors (ER) has been shown to be beneficial for the WAT stock pattern, leading to the insulin-sensitive phenotype, authors have described the risk of these receptors' activation, contributing to neoplasia development. The selective activation of beta-type ER (ERß) seems to be a promising strategy in the treatment of energy imbalance, acting on several tissues of metabolic importance and allowing an intervention with less risk for the development of estrogen-dependent neoplasia. However, the literature on the risks and benefits of selective ERß activation still needs to increase. In this review, several aspects related to ERß were considered, such as its physiological role in tissues of energy importance, beneficial effects, and risks of its stimulation during menopause. PubMed, SciELO, Cochrane, and Medline/Bireme databases were used in this study.
Assuntos
Biomarcadores , Pós-Menopausa/metabolismo , Receptores de Estradiol/metabolismo , Tecido Adiposo/metabolismo , Suscetibilidade a Doenças , Estrogênios/metabolismo , Feminino , Regulação da Expressão Gênica , Humanos , Doenças Metabólicas/etiologia , Doenças Metabólicas/metabolismo , Neoplasias/tratamento farmacológico , Neoplasias/etiologia , Neoplasias/metabolismo , Especificidade de Órgãos , Receptores de Estradiol/genética , Receptores de Estrogênio/metabolismo , Transdução de SinaisRESUMO
It is known that spontaneously hypertensive rats (SHR) present a marked encephalopathy, targeting vulnerable regions such as the hippocampus. Abnormalities of the hippocampus of SHR include decreased neurogenesis in the dentate gyrus (DG), partial loss of neurons in the hilus of the DG, micro and astrogliosis and inflammation. It is also known that 17ß-estradiol (E2) exert neuroprotective effects and prevent hippocampal abnormalities of SHR. The effects of E2 may involve a variety of mechanisms, including intracellular receptors of the ERα and ERß subtypes or membrane-located receptors, such as the G protein-coupled estradiol receptor (GPER). We have now investigated the protective role of GPER in SHR employing its synthetic agonist G1. To accomplish this objective, 5 month-old male SHR received 150 µg/day of G1 during 2 weeks. At the end of this period, we analyzed neuronal progenitors by staining for doublecortin (DCX), and counted the number of glial fibrillary acidic protein (GFAP)-labeled astrocytes and Iba1-stained microglial cells by computerized image analysis. We found that G1 activation of GPER increased DCX+ cells in the DG and reduced GFAP+ astrogliosis and Iba1+ microgliosis in the CA1 region of hippocampus. We also found that the high expression of proinflammatory makers IL1ß and cyclooxygenase 2 (COX2) of SHR was decreased after G1 treatment, which correlated with a change of microglia phenotype from the activated to a resting morphology. Additionally, G1 treatment increased the anti-inflammatory factor TGFß in SHR hippocampus. Altogether, our results suggest that activation of GPER plays a neuroprotective role on the encephalopathy of SHR, an outcome resembling E2 effects but avoiding secondary effects of the natural hormone.
Assuntos
Receptor alfa de Estrogênio/metabolismo , Receptor beta de Estrogênio/metabolismo , Hipocampo/anormalidades , Hipocampo/patologia , Encefalopatia Hipertensiva/metabolismo , Inflamação/metabolismo , Neurogênese , Receptores Acoplados a Proteínas G/metabolismo , Animais , Astrócitos/metabolismo , Proteína Duplacortina , Receptor alfa de Estrogênio/agonistas , Receptor alfa de Estrogênio/genética , Receptor beta de Estrogênio/agonistas , Receptor beta de Estrogênio/genética , Proteína Glial Fibrilar Ácida , Encefalopatia Hipertensiva/tratamento farmacológico , Masculino , Microglia/metabolismo , Quinolinas/farmacologia , Quinolinas/uso terapêutico , Ratos , Ratos Endogâmicos SHR , Receptores de Estradiol/agonistas , Receptores de Estradiol/metabolismo , Receptores Acoplados a Proteínas G/agonistas , Receptores Acoplados a Proteínas G/genéticaRESUMO
The accessory ß1 subunit modulates the Ca2+- and voltage-activated K+ (BK) channel gating properties mainly by increasing its apparent Ca2+ sensitivity. ß1 plays an important role in the modulation of arterial tone and blood pressure by vascular smooth muscle cells (SMCs). 17ß-estradiol (E2) increases the BK channel open probability (Po) in SMCs, through a ß1 subunit-dependent modulatory effect. Here, using molecular modeling, bioinformatics, mutagenesis, and electrophysiology, we identify a cluster of hydrophobic residues in the second transmembrane domain of the ß1 subunit, including the residues W163 and F166, as the binding site for E2. We further show that the increase in Po induced by E2 is associated with a stabilization of the voltage sensor in its active configuration and an increase in the coupling between the voltage sensor activation and pore opening. Since ß1 is a key molecular player in vasoregulation, the findings reported here are of importance in the design of novel drugs able to modulate BK channels.
Assuntos
Estradiol/metabolismo , Ativação do Canal Iônico , Subunidades beta do Canal de Potássio Ativado por Cálcio de Condutância Alta/química , Miócitos de Músculo Liso/metabolismo , Cálcio/metabolismo , Células HEK293 , Humanos , Potenciais da Membrana , Técnicas de Patch-Clamp/métodos , Subunidades Proteicas , Receptores de Estradiol/metabolismoRESUMO
The dynamic equilibrium between spermatogonial proliferation and testicular apoptosis determines the progression of spermatogenesis in amphibians. Estrogens and their receptors play a central role in regulating spermatogenesis in vertebrates, and in some species of anurans, estradiol (E2 ) is involved in the regulation of spermatogonial proliferation and apoptosis of germ cells. Bidder's organ (BO) is a structure characteristic of Bufonidae that has historically been compared to an undeveloped ovary. In adult Rhinella arenarum males, BO is one of the main sources of plasma E2 . The aim of this study was 1) to describe the seasonal variations in testicular apoptosis, spermatogonial proliferation, and cellular proliferation in BO; and 2) to analyze the presence and localization of estrogen receptor ß (ERß) in the testes and BO of R. arenarum. Testicular fragments and BOs from animals collected during the year were labeled with 5-bromo-2'-deoxyuridine (BrdU) and BrdU incorporation was determined using immunohistochemistry. Apoptosis in testicular sections was detected using the TUNEL method, and ERß localization was assessed using immunohistochemistry in testes and BOs. The results indicate that spermatogonial proliferation is highest during the reproductive season and that cysts of spermatocytes and spermatids undergo apoptosis during the postreproductive season. Furthermore, the proliferation of follicular cells is highest during the reproductive and postreproductive seasons. ERß was primarily detected by immunolocalization in Sertoli cells, follicular cells, and oocytes. Taken together, these results suggest that cysts that do not form spermatozoa are removed from testes by apoptosis and that estrogens regulate both spermatogenesis and oogenesis in adult males of R. arenarum.
Assuntos
Apoptose/fisiologia , Bufonidae/fisiologia , Proliferação de Células , Espermatogênese/fisiologia , Testículo/citologia , Testículo/fisiologia , Animais , Bufonidae/anatomia & histologia , Receptor beta de Estrogênio/metabolismo , Masculino , Receptores de Estradiol/metabolismo , Células de SertoliRESUMO
In this work we studied the influence of sex hormones on heart and mitochondrial functions, from adult castrated female and male, and intact rats. Castration was performed at their third week of life and on the fourth month animals were subjected to heart ischemia and reperfusion. Electrocardiogram and blood pressure recordings were made, cytokines levels were measured, histopathological studies were performed and thiobarbituric acid reactive species were determined. At the mitochondrial level respiratory control, transmembranal potential and calcium management were determined; Western blot of some mitochondrial components was also performed. Alterations in cardiac function were worst in intact males and castrated females as compared with those found in intact females and castrated males, cytokine levels were modulated also by hormonal status. Regarding mitochondria, in those obtained from hearts from castrated females without ischemia-reperfusion, all evaluated parameters were similar to those observed in mitochondria after ischemia-reperfusion. The results show hormonal influences on the heart at functional and mitochondrial levels.
Assuntos
Coração/fisiopatologia , Mitocôndrias Cardíacas/fisiologia , Traumatismo por Reperfusão Miocárdica/fisiopatologia , Animais , Castração , Citocromos c/metabolismo , Citocinas/metabolismo , Estradiol/sangue , Feminino , Masculino , Traumatismo por Reperfusão Miocárdica/sangue , Miocárdio/metabolismo , Miocárdio/patologia , Ratos , Ratos Sprague-Dawley , Receptores de Estradiol/metabolismo , Caracteres Sexuais , Testosterona/sangue , Substâncias Reativas com Ácido Tiobarbitúrico/metabolismoRESUMO
Progesterone (P(4)) and estradiol (E(2)) regulate many cell functions through their interaction with specific intracellular receptors, which require the participation of coactivators such as SRC-1 and SRC-3 for enhancing their transcriptional activity. Coactivator expression is altered in many cancers and in some of them their expression is regulated by P(4) and E(2). In this study, we determined progesterone and estrogen receptor isoform expression in two human astrocytoma cell lines with different evolution grade (U373, grade III; and D54, grade IV) by Western Blot. We studied the role of P(4) and E(2) on SRC-1 and SRC-3 expression in U373 and D54 cell lines by RT-PCR and Western blot. In U373 cells, P(4) did not modify SRC-1 expression, but in D54 cells it increased SRC-1 mRNA expression after 12 h of treatment without significant changes after 24 h. P(4) also increased SRC-1 protein content after 24 h, but reduced it after 48 h. E(2) did not change SRC-1 expression in any cell line. SRC-3 expression was not regulated by either E(2) or P(4). Our data suggest that SRC-1 and SRC-3 expression is differentially regulated by sex steroid hormones in astrocytomas and that P(4) regulates SRC-1 expression depending on the evolution grade of human astrocytoma cells.
Assuntos
Astrocitoma/metabolismo , Estradiol/metabolismo , Regulação Neoplásica da Expressão Gênica , Glioblastoma/metabolismo , Coativador 1 de Receptor Nuclear/metabolismo , Coativador 3 de Receptor Nuclear/metabolismo , Progesterona/metabolismo , Western Blotting , Linhagem Celular Tumoral , Humanos , Coativador 1 de Receptor Nuclear/genética , Coativador 3 de Receptor Nuclear/genética , Isoformas de Proteínas/metabolismo , RNA Mensageiro/metabolismo , Receptores de Estradiol/metabolismo , Receptores de Estrogênio/metabolismo , Receptores de Progesterona/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Fatores de TempoRESUMO
The objective of this comparative study was to determine the influence of changes in estradiol and progesterone during ovulatory vs. anovulatory cycles on levels of estradiol receptor (ER) and progesterone receptor (PgR) in endometrium. Thirty women (range age 20-35 years) were divided into three groups: women with a history of habitual abortion, obese women with menstrual disorders, and women with regular ovulatory cycles as well as proven fertility. A single venous blood sample and an endometrial sample were simultaneously obtained during the secretory phase of the menstrual cycle, in order to measure estradiol and progesterone levels and ER and PgR concentrations in cytosol and salt-extracted nucleosol. Plasma estradiol levels were not different between groups. Plasma progesterone was two times higher in fertile women than in habitual aborters. In endometrial tissue, progesterone content was 200 times higher in fertile women than in habitual aborters. ER and PgR were lower in the cytosol than in the nuclear fraction in fertile and obese women. Both receptors were at their lowest level in the cytosol and nuclear compartment of women with recurrent miscarriage. Fluctuations mainly in the sex hormone progesterone, in plasma and endometrium tissue, could interfere with ER and PgR levels.
Assuntos
Aborto Habitual/metabolismo , Endométrio/metabolismo , Distúrbios Menstruais/metabolismo , Progesterona/metabolismo , Receptores de Estradiol/metabolismo , Receptores de Progesterona/metabolismo , Adulto , Feminino , Humanos , Infertilidade Feminina/metabolismo , Obesidade , Receptores de Estradiol/genética , Receptores de Progesterona/genéticaRESUMO
Six microsomal population of estradiol and androgen receptors have been characterized in human benign prostatic hypertrophy (BPH) and prostate cancer (PCa). Estradiol receptor (ER) and androgen receptors (AR) were extracted using 0.6 M KCL and determined by the dextran-coated charcoal method. ER and AR levels were smaller in BPH plasma membranes (PM) than in Pca cases. For functions 3, 4, 6, the ER values in PCa were 25-38% less with regard to BPH ER values. Whereas in PCa, AR values obtained in all fractions were higher when compared to BPH AR values. In benign prostatic hypertrophy and prostatic cancer, ER and AR levels were significantly higher in the nuclear fraction. In the nuclear fraction, ER and AR levels in BPH and PCa were significantly different. The subcellular distribution of AR and ER in BPH and PCa constitutes a reservation mechanism and processing a receptors for their continued growth.
Assuntos
Neoplasias da Próstata/ultraestrutura , Receptores Androgênicos/metabolismo , Receptores de Estradiol/metabolismo , Frações Subcelulares/metabolismo , Humanos , Masculino , Microscopia EletrônicaRESUMO
The slow Ca2+-activated K+ current (sIAHP) was recorded in CA1 pyramidal neurons in hippocampal slices obtained from ovariectomized (OVX) or sham OVX (control) female rats. The sIAHP was significantly larger in cells from OVX rats than in cells from control rats. Superfusion with 5-100 nm 17beta-estradiol (E2) caused a progressive decrease in the sIAHP in cells from OVX rats but not in cells from control rats. In slices from OVX rats injected with 10 microg of E2 24 and 48 hr before they were killed, superfusion with E2 did not modify the sIAHP. In neurons from OVX rats, but not in neurons from control rats, E2 significantly increased both the number of action potentials and the burst duration generated by depolarizing pulses. The inactive isomer 17alpha-estradiol had no effect. The impermeant protein conjugate E2--BSA was as effective as free E2 at decreasing the sIAHP. Ca2+ spikes were also depressed by E2 in neurons from OVX rats, but not in control rats. A decrease in the intracellular Ca2+ signal, correlating with the inhibition of the Ca2+ spike and sIAHP produced by E2, was observed only in neurons from OVX rats. Our results indicate that ovariectomy increases the sIAHP and depresses excitability, whereas bath application or priming with E2 decreases the sIAHP, thus promoting excitability. These effects of E2 on the sIAHP and excitability, which are stereospecific and presumably mediated by membrane-bound receptors, could contribute to the hormonal regulation of synaptic plasticity and epileptiform activity as well as to learning and cognitive abilities dependent on the function of hippocampal neural circuits.