Structural evaluation and immunolocalization of SHBG, AR and importins in the epididymis of rats treated with H2 receptor antagonist - cimetidine

Abstract

Cimetidine, a H2 receptor antagonist that inhibits gastric secretion, has been used for duodenal and gastric ulcers. However, some collateral effects were observed in cimentidine-treated patients such as loss of libido, impotence, gynecomastia, and reduced sperm count. Regarding the antihistaminergic and antiandrogenic actions of cimetidine, as well as the scarce literature concerning the cimetidine effect on male genital ducts, this study aims to evaluate the structural and functional alterations induced by this drug in the epididymis of cimetidine-treated rats. Twenty male rats will be distributed into control (CG, n=10) and experimental (EG, n=10) groups. The animals from EG will receive daily cimetidine intrapetoneal injections (100 mg/kg) for 50 consecutive days. CG animals will receive saline solution. The epididymis cauda from four animals will be collect and store at -80°C for Western Blot. The epididymal cauda of the remaining six animals will be fixed and processed for embedding in historesin and paraffin. Fragments of epididymis cauda will also be processed for embedding in Araldite for Transmission Electron Microscopy. The sections will be stained with hematoxilin and eosin (HE) or with Masson's Trichrome for morphological and morphometrical analyses. The following morphometrical analyses will be performed: diameters of the epididymal duct sections, area occupied by connective tissue and number of epithelial cells. The birrefringent fibrous tissue (collagen) will be analyzed under polarized light. In the paraffin sections, the TUNEL method and immunofluorescence for detection of androgen receptors (AR), steroid hormone binding globulin (SHBG) and importin-± will be performed. The area occupied by AR and SHBG will be quantified. The differences between the groups will also be confirmed by Western Blot. The quantitative and morphometric parameters will be statistically analyzed to evaluate differences between the groups.