Effects of mild diabetes on extracellular matrix and urethral striated muscle of pregnant rats

Abstract

during pregnancy is associated with high levels of urinary incontinence and pelvic floor muscle dysfunction. Mild diabetes can lead to changes in urethral striated muscle and extracellular matrix in pregnant rats considering both structures as a whole system responsible for urinary continence. METHODS: Ninety-two female Wistar rats were distributed in four experimental groups: virgin, pregnant, diabetic and diabetic pregnant. All experimental procedures were approved by the Ethics Committee on Animal Experiments of the Botucatu Medical School – UNESP (Protocol Number 846). Mild diabetes was induced at the first day of birth by subcutaneous administration of streptozotocin at a dose of 100 mg/kg body weight. In adult life, parental non-diabetic female rats were mated with non-diabetic males to obtain newborns. On day 21 of the pregnancy, the rats were lethally anesthetized and the urethra and vagina were extracted as a unit. Urethral and vaginal sections were cut and analyzed by a) cytochemical staining for extracellular matrix and muscle components; b) immunohistochemistry to identify fast and slow muscle fibers; and c) transmission electron microscopy for ultrastructural analysis of urethral striated muscle. RESULTS: In comparison to the three control groups, variations in the urethral striated muscle and extracellular matrix from diabetic pregnant rats were observed including: thinning, disorganization, atrophy, fibrosis, increased blood vessels, accumulation of subsarcolemmal and intermyofibrillar mitochondria, lipid droplets and glycogen granules associated with co-localization of fast and slow fibers and a steady decrease in the proportion of fast to slow fibers. CONCLUSIONS: Mild diabetes and pregnancy can lead to time-dependent disorder and tissue remodeling in which the urethral striated muscle and extracellular matrix has a fundamental function.Tese apresentada ao Programa de Pos-Graduacao em Ginecologia, Obstetricia e Mastologia, da Faculdade de Medicina de Botucatu - UNESP, para obtencao do titulo de Doutor, em 1 de marco de 2013.OBJETIVO: verificar a associacao entre a ocorrencia de IU e funcao muscular do AP com os disturbios hiperglicemicos gestacionais. METODOS: o estudo foi desenvolvido no Ambulatorio de Pre-Natal do Hospital das Clinicas da Faculdade de Medicina de Botucatu – FMB/UNESP e aprovado pelo Comite de Etica em Pesquisa da Faculdade de Medicina de Botucatu (protocolo no. 426/08). As gestantes foram avaliadas pela palpacao digital, perineometria e eletromiografia (EMG). No primeiro momento da avaliacao (M1), entre a 24a e 32a semanas gestacionais, avaliamos 115 gestantes divididas em dois grupos, 82 gestantes normoglicemicas (NG) e 33 hiperglicemicas (HG), e no segundo momento (M2), entre a 34a e 38a semana gestacional, 38 e 28 NG e HG, respectivamente, retornaram para continuar as avaliacoes. A analise estatistica foi realizada com nivel de significância de 5%. RESULTADOS: as hiperglicemicas apresentaram idade cronologica e gestacional mais avancadas, alem de menor estatura. Houve diferenca significativa na distribuicao peso-altura entre os grupos no M1. Nao houve diferenca entre os grupos, no M2 quanto a ocorrencia de IU. Na analise intergrupos da palpacao digital, observamos reducao da forca muscular, enquanto que algumas mantiveram ou aumentaram. Na comparacao das avaliacoes com perineometro e EMG, entre e intragrupos, nao houve diferencas significativas. CONCLUSAO: no presente trabalho, nao houve diferenca estatistica entre os grupos NG e HG.