Experimental model of biliary obstruction in young rats: histological analysis and pharmacological modulation with prednisolone e pentoxifylline

Abstract

Many chronic liver diseases lead to progressive establishment of hepatic fibrosis, condition that can ultimately result in loss of organ function and severe portal hypertension demanding hepatic transplantation. The exact physiopathology of that process is not fully understood. Within the last decades, some studies have been conducted in order to demonstrate the possibility of drug modulation of hepatic fibrogenesis. Particularly related to biliary obstruction, it has been suggested that administration of corticosteroids could promote better late outcomes for biliary atresia children submitted to Kasai's portoenterostomy. There is no published experimental study related to that issue, and described models used to test potential antifibrogenic drugs, such as pentoxifylline, have not included growing animals. The proposition of this project is to manage an experimental study in order to analyze fibrogenesis and ductular proliferation secondary to biliary obstruction in growing animals and to analyze how corticosteroid and pentoxifylline administration affect those processes. Around 100 weaning Wistar rats (21st or 22nd days) will be submitted to laparotomy and common bile duct ligation (CBDL) or sham surgery (SHAM). Animals will be allocated into 5 groups, according to surgical procedure and administered solution: 1. CBDL + distilled water; 2. SHAM + distilled water; 3. CBDL + pentoxifylline (PTX); 4. CBDL + prednisolone (PRED); 5. CBDL + pentoxifylline + prednisolone (PTX+PRED). Each group will be further divided into 2 subgroups according to the length of the experiment (15 or 30 days). At the end of the defined period, animals will be weighed and a hepatic fragment will be collected from each one for histological (hematoxylin-eosin and Sirius red stains) and immunohistochemical / immunofluorescent analysis (using monoclonal antibodies against collagen III, TGF², VEGF and cytokeratin 7). Slides will be examined for quantitative analysis of marked areas (digital morphometry) and data obtained will be statistically processed to determine difference among groups. (AU)