Danos testiculares em ratos submetidos a diferentes doses de chumbo: Avaliação histomorfométrica, ultraestrutural e bioquímica

• Autor(a) principal: Costa, Kyvia Lugate Cardoso
• Data de Publicação: 2013
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/263
• topic: Metal pesado; Testículo; Estresse oxidativo; Túbulo seminífero; Células de Leydig; Heavy metal; Testis; Oxidative stress; Seminiferous tubule; Leydig cells; CNPQ::CIENCIAS BIOLOGICAS::BIOLOGIA GERAL

Lead is one of the most common environmental pollutants with no biological function known and potentially able to induce several toxic effects on male and animal reproductive system. In this context, the aim of this study was to evaluate the effects of subchronic exposure to lead acetate on testes of Wistar rats. Twenty-five adult Wistar rats were used and divided into five groups: Group I (control) received distilled water and treated groups (II, III, IV and V) received lead acetate solution at concentrations of 16, 32, 64 and 128 mg Pb/kg, respectively, by gavage for 30 consecutive days. Testicular fragments were fixed and processed for light and electron microscopy. The concentration of lead in the testis, the activity of antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) and serum testosterone levels were quantified. Structural and ultrastructural evaluations revealed different levels of pathology in the seminiferous epithelium of animals intoxicated by lead, such as vacuolization, shedding of germ cells, presence of apoptotic bodies and large lipid droplets, and rupture of blood-testis barrier. Presence of edema was observed in the intertubule of animals treated with lead. Furthermore, ultrastructural evaluations revealed changes in Leydig cells and blood vessels. Tunica propria decreased in groups II and III, while the percentage of seminiferous epithelium was lower in groups IV and V. There was an increase in the volume of lymphatic space in groups III and V. The proportion of lymphatic space was higher in groups III, IV and V compared to control. Significant reduction in volumetric proportion of Leydig cells in groups exposed to lead was observed. There was an increase in the volume and proportion of connective tissue in the treated groups compared to control. The volume and proportion of macrophages did not differ between experimental groups, except in group II. Cytoplasmic volume and volume of Leydig cells decreased in the treated groups compared to control. The percentage of tubular lumen increased in groups II, IV and V. Reduction in height of the epithelium and increase in diameter of tubular lumen were observed in all rats exposed to lead. Population of germ cells in seminiferous epithelium decreased in the treated groups, whereas the number of Sertoli cells remained unchanged. Daily sperm production and sperm reserves, both per gram of testis decreased in groups III, IV and V. A dose-dependent increase in lead concentration in the testes of mice exposed to metal was observed. There was significant reduction in the activity of catalase (CAT) and superoxide dismutase (SOD) as in serum testosterone levels in treated groups. In conclusion, the results suggest that subchronic exposure of lead can induce oxidative stress by reducing the activity of antioxidant enzymes, promoting a series of morphological, morphometric and ultrastructural testicle, inhibiting steroidogenesis and thus compromising sperm function.