Thiamine deficiency results in metabolic acidosis and energy failure in cerebellar granule cells: An in vitro model for the study of cell death mechanisms in Wernicke's encephalopathy

Thiamine deficiency (TD) in both humans and experimental animals results in severe compromise of mitochondrial function and leads to selective neurona l cell death in diencephalic and cerebellar structures. To examine further the influence of TD on neuronal survival in relation to metabolic changes, primary cultures of rat cerebellar granule cells were exposed to thiamine-d eficient medium for up to 7 days in the absence or presence of the central thiamine antagonist pyrithiamine (Py), Exposure of cells for 7 days to thia mine-deficient medium alone resulted in no detectable cell death. On the ot her hand, 50 mu M Py treatment led to reductions of thiamine phosphate este rs, decreased activities of the thiamine-dependent enzymes alpha-ketoglutar ate dehydrogenase and transketolase, a twofold increase in lactate release (P < 0.001), a lowering of pH, and significant (58%, P < 0.001) cell death. DNA fragmentation studies did not reveal evidence of apoptotic cell death. Addition of 50 mu M alpha-tocopherol (vitamin E) or 100 mu M of butylated hydroxyanisole (BHA) to Py-treated cells resulted in significant neuroprote ction. On the other hand, addition of 10 mu M MK-801, an NMDA receptor anta gonist, was not neuroprotective. These results suggest that reactive oxygen species (ROS) play a major role in thiamine deficiency-induced neuronal ce ll death. Insofar as this experimental model recapitulates the metabolic an d mitochondrial changes characteristic of thiamine deficiency in the intact animal, it might be useful in the elucidation of mechanisms involved in th e neuronal cell death cascade resulting from thiamine deficiency. (C) 2000 Wiley-Liss, Inc.