Proposta para um modelo experimental de carcinogênese utilizando Benzopireno B[A]P em ratos

Abstract

The aim of this study was to propose an experimental model of benzopyrene-induced carcinogenesis. In a proportion of 9 mg/kg, B[a]P, a hydrocarbon widely known for its tumor-inducing characteristic, was applied subcutaneously. After analyzing the extent of cellular proliferation in each one of the organs affected by B[a]P (skin, liver and lung), hematoxylin and eosin (H.E) staining was used for histological assay. Eighteen male, adult, healthy exemplars with weight ranging from 150 to 200g have been used. They were divided into two groups (control and test), each one with nine animals, and euthanized on days 15, 30 and 45 post application. The fragments were sectioned, stained with H.E and then observed by macroscopy and microscopy. Inflammatory alterations were seen in all groups, but the lung tissue of the experimental groups presented Balt hyperplasic alterations. This study showed that B[a]P subcutaneous application is a simple method and may constitute a suitable model of carcinogenesis; another conclusion is that pre-carcinogenic lesions occurred in the lungs. Some authors regard Balt nodular hyperplasia as possible pre-carcinogenic lesions and suggest that the subcutaneous injection may account for a proper model when used in larger doses and for longer observation periods. The main secondary alterations were found in the skin, with ulceration, vessel neoformation, exudation, cellular infiltrate; in the liver, with vascular congestion, cellular tumescence, exudation and irregular fibers; and in the lungs, with vascular congestion.