EXPERIMENTAL CARCINOGENICITY STUDIES OF N-NITROSOMETHYLUREA IN RATS

Abstract

The object of this study was to assess the tumour promoting potential of Phenobarbital (PB) after initiation with NNitrosomefhylurea (NMU). In the NMU group, hepatocytes showed mild toxic changes. The kidney manifested degenerative changes. There were squamous cell zyperplastic changes in the stomach. In the NMU + PB group, the liver showed toxic changes like vacuolation, granularity and necrosis of hepatocytes as well as preneoplastic changes like clear cell foci and focal hepatocellular dysplasia. U/trastructurallythe nuclei of hepatic cells showed an increase in interchromation granules. Besides, numerous vacuoles were also seen in the cytoplasm which could be due to dilatation and vesiculation of RER and SER due to ingress of water. The ofher changes included hyperaemia and tubular degeneration in the kidney, perivascular collection of mononuclear cells in the lungs, mild gliosis with focal proliferation of meningeal cells in the brain. In the testes, there were necrosis of spermatids and accumulation of debris in the seminiferous Tubules. Mammary gland showed adenoma toes hyperplasia. The changes in the urinary bladder mucosa varied from marked epithelial proliferation to papillomatous foldings.

Keywords

• phenobarbital
• n-nitrosomethyl urea