INDUCTION OF APOPTOSIS IN CULTURED MIDBRAIN CELLS FROM EMBRYONIC MICE

Midbrain cells from embryonic mice were cultured at a high cell densit y for 4 days to observe proliferation and differentiation, Results ind icate that UVC radiation caused dose-dependent inhibition of their pro liferation and differentiation. Inhibitory effects of UVC radiation (p er unit dose) were greater on cell differentiation than on proliferati on. The percentage of apoptotic cells in the groups irradiated with (1 5) J/m(2) became significantly higher than the control level 2 h after irradiation, The percentage of apoptotic cells increased with time in a dose associated fashion and reached a maximum al about 7.5 h after irradiation, Then it decreased with time and returned to the control l evel at about 30 h after irradiation. Metabolic inhibitors could postp one occurrence of intermediate apoptosis (>2 h, but <20 h) if they wer e added at suitable times after irradiation but failed to prevent a de layed apoptosis (>24 h). Results showed that UVC radiation induced int ermediate apoptosis which could be postponed by metabolic inhibitors, and that UVC could also induce delayed apoptosis with the addition of metabolic inhibitors, The result that UVC radiation could induce inter mediate apoptosis in the midbrain cells was different from previous da ta obtained using cells of an established cell line, The implications of the results for the understanding of the mechanism involved are dis cussed. (C) 1997 by Radiation Research Society.