DNA synthesis in the cerebellar Purkinje neurons of early postnatal rats: an extra DNA or a repair process?

DNA synthesis and Feulgen - DNA content in Purkinje neurons were examined in early postnatal rats exposed to cis-dichlorodiammineplatinum II (cis-DDP) and (3H) thymidine. Autoradiographic data revealed a significant although low labelling in control rats on postnatal day 10 to 11; the incorporation deeply decreased after cis-DDP administration. Cytophotometry showed formation of some Purkinje cells with hyperdiploid DNA content in control animals between postnatal day 11 and 16, whereas in cis-DDP treated rats all cells remained diploid. A close correlation between the formation of hyperdiploid Feulgen-DNA nuclei and the incorporation of (3H) thymidine provides new, indirect support for an actual DNA surplus in some Purkinje cells, although the incorporation of some of (3H) thymidine due to an enhanced turnover and or repair of DNA in Purkinje cells of 10 to 11 days old rats is not excluded.