Caracterização do remodelamento cardíaco de camundongos mdx submetidos a treinamento aeróbico
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Data
2022-09-05
Autores
Cabanelas, Luciana Alécio [UNIFESP]
Orientadores
De Oliveira, Flavia [UNIFESP]
Tipo
Tese de doutorado
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ISSN da Revista
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Resumo
A distrofia muscular de Duchenne (DMD) é uma doença hereditária progressiva e com
envolvimento cardíaco. Este estudo teve como objetivo avaliar os mecanismos envolvidos no
remodelamento cardíaco do ventrículo esquerdo de modelos experimentais para a DMD
(camundongos mdx) submetidos ao exercício físico aeróbico, a fim de acelerar a progressão
da doença. Foram utilizados camundongos C57BL/10 e C57BL/10-DMDMdx, machos, com 6
meses de idade. O protocolo de exercício físico teve duração de oito semanas para os grupos
treinados (Mdx-T), enquanto os animais dos grupos controle (C) e mdx sedentário (Mdx-S)
não passaram por intervenção. Após a eutanásia, os corações foram removidos para serem
submetidos às análises: morfométrica (análise da densidade dos núcleos e espessura dos
cardiomiócitos e análise do tecido conjuntivo); imunoistoquímica para análise in situ das
proteínas: MMP-2, MMP-9, COX-2 e 8-OHdG. Foi empregado o teste de t de Student para a
comparação entre os grupos em relação às variáveis da espessura dos cardiomiócitos, área do
perfil dos cardiomiócitos e estereologia do colágeno. Para a imunomarcação do 8-OHdG e
COX-2 utilizou-se ANOVA seguido de comparações múltiplas de Tukey. Como resultados,
as fotomicrografias indicaram que os grupos Mdx-S e Mdx-T apresentaram perda difusa dos
cardiomiócitos, aumento do espaço de matrix extracelular e das áreas de infiltrado
inflamatório e de tecido conjuntivo, sendo essas alterações mais evidentes no Mdx-T. A
análise morfométrica mostrou que a espessura dos cardiomiócitos dos animais Mdx-T foi
menor que a do Mdx-S. Na análise qualitativa da MMP-2 e 9, foi possível observar
imunoreatividade em áreas de acúmulo de tecido conjuntivo nos animais mdx, mais evidentes
nos grupo Mdx-T. A imunoexpressão da COX-2 foi maior nos animais do grupo Mdx-T do
que no Mdx-S e grupo C. Já a presença do 8-OHdG foi maior no grupo Mdx-T e Mdx-S
quando comparados ao grupo C. O protocolo de exercícios utilizado foi capaz de exacerbar o
quadro de degeneração e atrofia dos cardiomiócitos. Ainda nos animais Mdx-T houve maior
degradação do colágeno relacionado às MMPs e exacerbação do quadro inflamatório e
estresse oxidativo relacionado a danos ao DNA, evidenciados pela maior presença da COX-2
e do 8-OHdG, respectivamente.
Duchenne muscular dystrophy (DMD) is a progressive hereditary disease with cardiac involvement. This study aimed to evaluate cardiac remodeling pathways of left ventricle in an animal model of DMD (mdx mice) submitted to aerobic exercise. C57BL/10 and C57BL/10- DMDMdx mice, 6 months old, male, were used. The experimental protocol of physical exercise lasted eight weeks, in which the trained groups (Mdx-T) were submitted to a physical training protocol while the animals of groups control (C) and sedentary mdx (Mdx –S) did not undergo intervention. After euthanasia, the hearts were removed to be submitted to the following analyses: morphometric (analysis of nuclei density and cardiomyocyte thickness and analysis of connective tissue); immunohistochemistry for in situ analysis of proteins: MMP-2, MMP-9, COX-2 and 8-OHdG. Student's t test was used for independent samples in the comparison between groups in relation to the variables cardiomyocyte thickness, cardiomyocyte profile area and collagen stereology. Regarding 8-OHdG and COX-2 immunostaining, ANOVA and Tukey's multiple comparisons were used. The photomicrographs indicated that the Mdx-S and Mdx-T groups showed diffuse loss of cardiomyocyte, increased extracellular matrix space and areas of inflammatory infiltrate and connective tissue, these alterations being more evident in the Mdx-T group. The morphometric analysis showed that the thickness of the cardiomyocytes of the Mdx-T animals was smaller than that of the Mdx-S. In the qualitative analysis of MMP2 and 9, it was possible to observe their presence in areas of collagen tissue accumulation in mdx animals, more evident in the Mdx-T groups. The immunoexpression of COX-2 was higher in the animals of the Mdx-T group than in the Mdx-S and was higher than in C group. The presence of 8-OHdG was higher in the Mdx-T and Mdx-S groups when compared to C group. The aerobic training protocol was able to increase the process of degeneration and atrophy of cardiomyocytes. In Mdx-T group, there was greater degradation of collagen related to MMPs and exacerbation of the inflammatory condition and oxidative stress related to DNA damage, evidenced by the enhanced presence of COX-2 and 8-OHdG, respectively.
Duchenne muscular dystrophy (DMD) is a progressive hereditary disease with cardiac involvement. This study aimed to evaluate cardiac remodeling pathways of left ventricle in an animal model of DMD (mdx mice) submitted to aerobic exercise. C57BL/10 and C57BL/10- DMDMdx mice, 6 months old, male, were used. The experimental protocol of physical exercise lasted eight weeks, in which the trained groups (Mdx-T) were submitted to a physical training protocol while the animals of groups control (C) and sedentary mdx (Mdx –S) did not undergo intervention. After euthanasia, the hearts were removed to be submitted to the following analyses: morphometric (analysis of nuclei density and cardiomyocyte thickness and analysis of connective tissue); immunohistochemistry for in situ analysis of proteins: MMP-2, MMP-9, COX-2 and 8-OHdG. Student's t test was used for independent samples in the comparison between groups in relation to the variables cardiomyocyte thickness, cardiomyocyte profile area and collagen stereology. Regarding 8-OHdG and COX-2 immunostaining, ANOVA and Tukey's multiple comparisons were used. The photomicrographs indicated that the Mdx-S and Mdx-T groups showed diffuse loss of cardiomyocyte, increased extracellular matrix space and areas of inflammatory infiltrate and connective tissue, these alterations being more evident in the Mdx-T group. The morphometric analysis showed that the thickness of the cardiomyocytes of the Mdx-T animals was smaller than that of the Mdx-S. In the qualitative analysis of MMP2 and 9, it was possible to observe their presence in areas of collagen tissue accumulation in mdx animals, more evident in the Mdx-T groups. The immunoexpression of COX-2 was higher in the animals of the Mdx-T group than in the Mdx-S and was higher than in C group. The presence of 8-OHdG was higher in the Mdx-T and Mdx-S groups when compared to C group. The aerobic training protocol was able to increase the process of degeneration and atrophy of cardiomyocytes. In Mdx-T group, there was greater degradation of collagen related to MMPs and exacerbation of the inflammatory condition and oxidative stress related to DNA damage, evidenced by the enhanced presence of COX-2 and 8-OHdG, respectively.
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Citação
CABANELAS, Luciana Alécio. Caracterização do remodelamento cardíaco de camundongos mdx submetidos a treinamento aeróbico. 2022. 75 f. Tese (Doutorado Interdisciplinar em Ciências da Saúde) - Instituto de Saúde e Sociedade, Universidade Federal de São Paulo, Santos, 2022.