Hepatic capillariasis in rats: a new model for testing antifibrotic drugs

Rats infected with the helminth Capillaria hepatica regularly develop septa l hepatic fibrosis that may progress to cirrhosis in a relatively short tim e. Because of such characteristics, this experimental model was selected fo r testing drugs exhibiting antifibrosis potential, such as pentoxifylline, gadolinium chloride and vitamin A. Hepatic fibrosis was qualitatively and q uantitatively evaluated in liver samples obtained by partial hepatectomy an d at autopsy. The material was submitted to histological, biochemical and m orphometric methods. A statistically significant reduction of fibrosis was obtained with pentoxifylline when administered intraperitoneally rather tha n intravenously. Gadolinium chloride showed moderate activity when administ ered prophylactically (before fibrosis had started), but showed a poor effe ct when fibrosis was well advanced. No modification of fibrosis was seen af ter vitamin A administration. Hydroxyproline content was correlated with mo rphometric measurements. The model appears to be adequate, since few animal s die of the infection, fibrosis develops regularly in all animals, and the effects of different antifibrotic drugs and administration protocols can b e easily detected.