Enhanced caspase activity during ethanol-induced apoptosis in rat cerebellar granule cells

The effects of ethanol on cerebellar granule cell death were examined in cu ltures maintained for either 5 days in vitro (immature) or 8 and 12 days in vitro (mature). Ethanol did not alter cell survival under the usual growth conditions (i.e., 10% serum and 415 mM KCl). However. in mature cultures e thanol enhanced apoptosis induced by either serum withdrawal or incubation in non-depolarizing media. In immature cultures, serum deprivation, but not non-depolarizing media, resulted in granule cell death that was enhanced b y ethanol. Serum removal increased both cleavage of the caspase-specific su bstrate N-acetyl-Asp-Glu-Val-Asp-7 amino-4-methylcoumarin (Ac-DEVD-amc) and the amount of active caspase-3. Inclusion of ethanol during the serum depr ivation augmented Ac-DEVD-amc cleavage without further increasing the amoun t of active caspase-3. This study demonstrates that when neurotrophic facto rs are limiting, ethanol is toxic to cerebellar granule cells regardless of maturation status. The ability of ethanol to promote apoptosis involves an increase in caspase activity, but this does not entail an increase in the proteolytic activation of caspase-3. (C) 1999 Elsevier Science B.V. All rig hts reserved.