Exposição pós-natal ao Bisfenol A em fêmeas com restrição proteica gestacional: efeitos sobre o desenvolvimento mamário e suscetibilidade à carcinogênese
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Data
2018-02-09
Autores
Varuzza, Muriele Bertagna
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Universidade Estadual Paulista (Unesp)
Resumo
Perturbações no ambiente uterino e nos estágios iniciais da vida, por fatores nutricionais e/ou alterações hormonais, podem predispor os recém-nascidos a doenças crônicas na vida adulta. A restrição proteica gestacional (RPG) e a exposição ao Bisfenol A (BPA), nas fases pré e pós-natal, alteram o desenvolvimento mamário e aumentam a suscetibilidade a carcinogênese mamária. Assim, este trabalho investigou os possíveis efeitos da RPG e sua associação com a exposição pós-natal ao BPA sobre o desenvolvimento da glândula mamária e a suscetibilidade à carcinogênese mamária induzida pela 7,12-dimetilbenzantraceno (DMBA). Fêmeas prenhes da linhagem Sprague-Dawley foram alocadas em quatro grupos experimentais: dieta normoproteica (DNP); dieta hipoproteica (DHP); DNP+BPA e DHP+BPA. O BPA (1 mg/L) foi ministrado na água de beber à prole do dia pós-natal (DPN) 21 até o DPN 51. No DPN 51, fêmeas da prole (n=10/grupo) foram eutanasiadas para avaliação das glândulas mamárias, enquanto o restante (n=11/grupo) recebeu dose única de DMBA (30 mg/kg, i.g.), e foram eutanasiadas no DPN 250 para avaliação de tumores mamários. A RPG e a exposição ao BPA não alteraram o crescimento da árvore mamária, as unidades de brotos e ductos terminais (TEBs e TDs), a proliferação celular (Ki-67), a expressão do receptor de estrógeno β (RE-β) e área ocupada por fibras colágenas nas glândulas mamárias no DPN 51. Entretanto, nos grupos DHP e DNP+BPA houve redução na área correspondente ao tecido epitelial glandular e a associação (DHP+BPA) aumentou a área ocupada pelo fat pad. A exposição ao BPA (DNP+BPA e DHP+BPA) aumentou os índices apoptóticos, a RPG aumentou a expressão do receptor de estrógeno α (RE-α) e a associação (DHP+BPA) aumentou os receptores de progesterona (RP) nas glândulas mamárias no DPN 51. Os grupos DHP, DNP+BPA e DHP+BPA apresentaram menor latência tumoral. Além disso, os grupos que receberam BPA apresentaram maior incidência e multiplicidade tumoral. Considerando esses resultados, podemos concluir que a RPG e o BPA aumentaram a suscetibilidade ao desenvolvimento de tumores mamários induzidos pela DMBA, mas a associação (DHP+BPA) não levou ao aumento do risco.
Disturbances in the uterine environment and in the early stages of life, due to nutritional factors and/or hormonal changes, may predispose newborns to chronic diseases in adult life. Gestational protein restriction (GPR) and exposure to Bisphenol A (BPA), in the pre and postnatal phases alter breast development and increase susceptibility to mammary carcinogenesis. Therefore, the aim of this study was to investigate the possible effects of GPR and its association with postnatal exposure to BPA on mammary gland development and on susceptibility to 7,12-dimethylbenzanthracene (DMBA) induced mammary carcinogenesis. For this purpose, pregnant females of the Sprague-Dawley strain were allocated into four experimental groups: normoprotein diet (NPD); hypoproteic diet (HPD); NPD+BPA and HPD+BPA. BPA (1 mg/L) was given in drinking water to offspring from postnatal day (PND) 21 to PND 51. At the PDN 51, offspring females (n=10/group) were euthanized for mammary glands evaluation, while the remainder (n=11/group) received a single dose of DMBA (30 mg/kg, ig) and were euthanized at the PND 250 for breast tumors evaluation. GPR and BPA exposure did not alter the growth of the mammary tree, number of bud and terminal duct (TEBs and TDs), cell proliferation (Ki-67), expression of estrogen receptor β (ER-β) and collagen fibers area in the mammary glands at PDN 51. However, in the HPD and NPD+BPA groups was a decreased area corresponding to the glandular epithelial tissue and the association (HPD+BPA) increased the fat pad. Exposure to BPA (NPD+BPA and HPD+BPA) increased apoptotic indexes, GPR increased estrogen receptors α expression (ER-α) while their association (HPD+BPA) increased progesterone receptors (PR) in the mammary glands. The groups HPD, NPD+BPA and HPD+BPA also showed lower tumor latency. In addition, the groups that received BPA presented higher tumor incidence and multiplicity. These results suggests that GPR and BPA exposure increased the susceptibility to mammary carcinogenesis induced by DMBA, but the association (HPD+BPA) did not increase the risk.
Disturbances in the uterine environment and in the early stages of life, due to nutritional factors and/or hormonal changes, may predispose newborns to chronic diseases in adult life. Gestational protein restriction (GPR) and exposure to Bisphenol A (BPA), in the pre and postnatal phases alter breast development and increase susceptibility to mammary carcinogenesis. Therefore, the aim of this study was to investigate the possible effects of GPR and its association with postnatal exposure to BPA on mammary gland development and on susceptibility to 7,12-dimethylbenzanthracene (DMBA) induced mammary carcinogenesis. For this purpose, pregnant females of the Sprague-Dawley strain were allocated into four experimental groups: normoprotein diet (NPD); hypoproteic diet (HPD); NPD+BPA and HPD+BPA. BPA (1 mg/L) was given in drinking water to offspring from postnatal day (PND) 21 to PND 51. At the PDN 51, offspring females (n=10/group) were euthanized for mammary glands evaluation, while the remainder (n=11/group) received a single dose of DMBA (30 mg/kg, ig) and were euthanized at the PND 250 for breast tumors evaluation. GPR and BPA exposure did not alter the growth of the mammary tree, number of bud and terminal duct (TEBs and TDs), cell proliferation (Ki-67), expression of estrogen receptor β (ER-β) and collagen fibers area in the mammary glands at PDN 51. However, in the HPD and NPD+BPA groups was a decreased area corresponding to the glandular epithelial tissue and the association (HPD+BPA) increased the fat pad. Exposure to BPA (NPD+BPA and HPD+BPA) increased apoptotic indexes, GPR increased estrogen receptors α expression (ER-α) while their association (HPD+BPA) increased progesterone receptors (PR) in the mammary glands. The groups HPD, NPD+BPA and HPD+BPA also showed lower tumor latency. In addition, the groups that received BPA presented higher tumor incidence and multiplicity. These results suggests that GPR and BPA exposure increased the susceptibility to mammary carcinogenesis induced by DMBA, but the association (HPD+BPA) did not increase the risk.
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Palavras-chave
restrição proteica gestacional, bisfenol A, desenvolvimento mamário, câncer de mama, carcinogênese química experimental, gestational protein restriction, bisphenol A, breast development, breast cancer, experimental chemical carcinogenesis