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Abstract(s)
O plexo coroide (CP) é uma estrutura altamente vascularizada localizada nos ventrículos do cérebro, envolvida numa grande variedade de funções cruciais no sistema nervoso central (SNC), não sendo só responsável pela produção do líquido cefalorraquidiano (CSF) mas também pela vigilância da sua composição química. A via de transdução do paladar deteta alguns tipos de moléculas, avaliando deste modo a composição química de fluidos, não apenas na cavidade oral, mas também em tecidos extra-orais, tais como: trato respiratório, trato gastrointestinal, testículos, queratinócitos, rins, tiroide e cérebro. Numa análise de microarrays de cDNA, o nosso grupo de investigação descreveu recentemente o envolvimento das hormonas sexuais na regulação de diversas vias de sinalização no CP, nomeadamente na via de transdução de sinal do paladar. Os desreguladores endócrinos (DE) são compostos exógenos que estão disseminados no ambiente e influenciam a homeostasia, o desenvolvimento e a proliferação celular, mimetizando ou inibindo a ação das hormonas endógenas ou alterando a regulação do sistema endócrino, causando efeitos adversos para a saúde. No grupo dos DEs que são químicos sintéticos, o composto estrogénico bisfenol A (BPA) é um dos mais abundantes no meio ambiente. O objetivo do presente estudo é analisar o efeito do 17-ß-estradiol (E2) na expressão dos genes envolvidos na via de transdução do paladar ex vivo e in vivo, bem como o efeito do BPA nesta via de sinalização. Nos estudos ex vivo utilizaram-se CPs de ratos Wistar Han recém-nascidos e foram aplicados estímulos de: i) E2 (0.1, 1, 10 e 100 nM) durante 6 horas, com e sem um pré-tratamento de 90 minutos com fulvestrant (ICI; 100 nM), um antagonista dos recetores de estrogénio (ERs); ii) BPA (10, 25, 50, 75 e 100 nM) durante 6 horas. O estudo in vivo foi efetuado em ratos Wistar Han fêmeas ovariectomizadas (OVX) com dois meses de idade. O efeito do E2 e do BPA nos níveis de mRNA foi analisado por PCR em tempo real do produto da transcrição reversa (RT-qPCR). Os ensaios ex vivo revelaram que o E2 regula negativamente a expressão de todos os genes analisados e, corroborando estes resultados, os testes in vivo mostraram que existe um aumento da expressão de todos os genes em ratos OVX em comparação com o controlo. No seu conjunto, os nossos resultados comprovam o estudo prévio de microarrays transcritómicos, de que a via do paladar é regulada por hormonas sexuais, e esclarecem o mecanismo molecular envolvido, onde, o pré-tratamento com ICI bloqueia o efeito do E2, indicando o envolvimento dos ERs. Por outro lado, os resultados do efeito do BPA mostram que este DE afeta a expressão dos genes da via de sinalização do paladar, revelando uma curva de expressão génica dose-resposta não monotónica. Os resultados deste estudo sugerem que a via de transdução do paladar no CP é regulada não só por hormonas endógenas mas também por compostos exógenos, tais como o BPA. Assim, podemos afirmar que o background hormonal e a exposição ambiental ao BPA parecem interferir na expressão dos componentes da via do paladar no CP, podendo afetar a vigilância química do CSF pelo CP, com possíveis consequências na homeostasia do SNC.
The choroid plexus (CP) is a highly vascularized structure located in the brain ventricles, involved in a wide variety of crucial functions in the central nervous system (SNC), being not only responsible for cerebrospinal fluid (CSF) production but also for the surveillance of its chemical composition. The taste transduction pathway detects some types of molecules, thereby evaluating the chemical content of fluids, not only in the oral cavity but also in extra-oral tissues, such as: respiratory tract, gastrointestinal tract, testis, keratinocytes, kidneys, thyroid and brain. In a cDNA microarray analysis, our research group recently described the involvement of sex hormones in the regulation of several signaling pathways in CP, namely the taste signal transduction pathway. Endocrine disrupters (DE) are exogenous compounds that are disseminated in the environment and influence homeostasis, development and cell proliferation, mimicking or inhibiting the action of endogenous hormones or altering the regulation of the endocrine system, causing adverse health effects. In the group of DEs that are synthetic chemicals, the estrogenic compound bisphenol A (BPA) is the most abundant in the environment. The aim of the present study is to analyze the effect of 17-ß-estradiol (E2) on the expression of genes involved in the taste transduction pathway ex vivo and in vivo, as well as the effect of BPA in this signaling pathway. In ex vivo studies CPs of newborns Wistar Han rats were used and were applied stimuli of: i) E2 (0.1, 1, 10 and 100 nM) for 6 hours, with and without a pre-treatment of 90 minutes with fulvestrant (ICI; 100 nM), an antagonist of estrogen receptors (ERs); ii) BPA (10, 25, 50, 75 and 100 nM) for 6 hours. The in vivo study was carried out in ovariectomized (OVX) female Wistar Han rats with two months of age. The effect of E2 and BPA in mRNA levels was analyzed by real time PCR of the reverse transcription product (RT-qPCR). The ex vivo assays revealed that E2 negatively regulates the expression of all genes analyzed and, corroborating these results, the in vivo tests showed that there is an increase of the expression of all genes in OVX rats compared to controls. Taken together, our results prove the previous study of transcriptomic microarrays, that the taste pathway is regulated by sex hormones, and clarify the molecular mechanism involved, where the pre-treatment with ICI blocks the E2 effect, indicating the involvement of the ERs. On the other hand, the results of BPA effect show that this DE affects the expression of taste signaling pathway genes, revealing a non-monotonic dose response curve of gene expression. The results of this study suggest that the taste transduction pathway in CP is regulated not only by endogenous hormones but also by exogenous compounds, such as BPA. Thus, we can affirm that the hormonal background and the environmental exposure to BPA seem to interfere with the expression of the taste pathway components in CP, which may affect the chemical surveillance of the CSF by CP, with possible consequences on SNC homeostasis.
The choroid plexus (CP) is a highly vascularized structure located in the brain ventricles, involved in a wide variety of crucial functions in the central nervous system (SNC), being not only responsible for cerebrospinal fluid (CSF) production but also for the surveillance of its chemical composition. The taste transduction pathway detects some types of molecules, thereby evaluating the chemical content of fluids, not only in the oral cavity but also in extra-oral tissues, such as: respiratory tract, gastrointestinal tract, testis, keratinocytes, kidneys, thyroid and brain. In a cDNA microarray analysis, our research group recently described the involvement of sex hormones in the regulation of several signaling pathways in CP, namely the taste signal transduction pathway. Endocrine disrupters (DE) are exogenous compounds that are disseminated in the environment and influence homeostasis, development and cell proliferation, mimicking or inhibiting the action of endogenous hormones or altering the regulation of the endocrine system, causing adverse health effects. In the group of DEs that are synthetic chemicals, the estrogenic compound bisphenol A (BPA) is the most abundant in the environment. The aim of the present study is to analyze the effect of 17-ß-estradiol (E2) on the expression of genes involved in the taste transduction pathway ex vivo and in vivo, as well as the effect of BPA in this signaling pathway. In ex vivo studies CPs of newborns Wistar Han rats were used and were applied stimuli of: i) E2 (0.1, 1, 10 and 100 nM) for 6 hours, with and without a pre-treatment of 90 minutes with fulvestrant (ICI; 100 nM), an antagonist of estrogen receptors (ERs); ii) BPA (10, 25, 50, 75 and 100 nM) for 6 hours. The in vivo study was carried out in ovariectomized (OVX) female Wistar Han rats with two months of age. The effect of E2 and BPA in mRNA levels was analyzed by real time PCR of the reverse transcription product (RT-qPCR). The ex vivo assays revealed that E2 negatively regulates the expression of all genes analyzed and, corroborating these results, the in vivo tests showed that there is an increase of the expression of all genes in OVX rats compared to controls. Taken together, our results prove the previous study of transcriptomic microarrays, that the taste pathway is regulated by sex hormones, and clarify the molecular mechanism involved, where the pre-treatment with ICI blocks the E2 effect, indicating the involvement of the ERs. On the other hand, the results of BPA effect show that this DE affects the expression of taste signaling pathway genes, revealing a non-monotonic dose response curve of gene expression. The results of this study suggest that the taste transduction pathway in CP is regulated not only by endogenous hormones but also by exogenous compounds, such as BPA. Thus, we can affirm that the hormonal background and the environmental exposure to BPA seem to interfere with the expression of the taste pathway components in CP, which may affect the chemical surveillance of the CSF by CP, with possible consequences on SNC homeostasis.
Description
Keywords
17ß-Estradiol Bisfenol A Plexo Coroide Via do Paladar