RESUMO
The effect of the sulfhdryl compound thiola on ultrastructural alterations induced by the anticancer drug methotrexate in the liver of rats was studied. Animals treated with methotrexate at a dose level of 0.004 mg/kg b.w. daily for 1,2 and 5 days showed numerous changes in the hepatocytes. The nuclei showed chromatin and in some cases it was fragmented. Mitochondria were elongated or bizare in shape and the RER were reduced and fragmented. Lysosomes were abundant and glycogen rosettes were depleted. The bile canaliculi appeared dilated with fragmented microvilli. Kupffer cells were hypertrophied indicating hyperactivity. On the other hand, treating animals with methotrexate [at the same dose and for the same periods] followed by injection of thiola [at a dose of 50 mg/kg b.w. daily for one, two and five days], caused an improvement in the fine structure of the hepatocytes. These findings suggest that thiola overcomes the hepatotoxic action of methotrexate