APOPTOTIC PROCESS OF CEREBELLAR DEGENERATION IN EXPERIMENTAL METHYLMERCURY INTOXICATION OF RATS

This report deals with the mechanism involved in the cerebellar degene ration following experimental methylmercury poisoning of male Wistar r ats. The cerebellar granule cells of animals that exhibited typical hi nd leg paresis were shrunken and displayed marked nuclear pyknosis. At the ultrastructural level, the nuclei of these cells were condensed a nd fragmented, features which are characteristic of apoptosis. Tn situ staining for DNA strand breaks revealed that the pyknotic nuclei were positively labeled. DNA fragmentation was confirmed by agarose gel el ectrophoresis; a ladder pattern of multiples of approximately 200-base pair fragments, typical of apoptosis, was observed with the cerebella r DNA of the methylmercury-treated animals. These observations suggest that the degeneration of cerebellar granule cells by alkyl mercury co mpounds involves an apoptotic process.