THIAMINE DEFICIENCY-INDUCED PARTIAL NECROSIS AND MITOCHONDRIAL UNCOUPLING IN NEUROBLASTOMA-CELLS ARE RAPIDLY REVERSED BY ADDITION OF THIAMINE

Culture of neuroblastoma cells in a medium of low-thiamine concentrati on (6 nM) and in the presence of the transport inhibitor amprolium lea ds to the appearance of overt signs of necrosis; i.e., the chromatin c ondenses in dark patches, the oxygen consumption decreases, mitochondr ia are uncoupled, and their cristae are disorganized. Glutamate formed from glutamine is no longer oxidized and accumulates, suggesting that the thiamine diphosphate-dependent alpha-ketoglutarate dehydrogenase activity is impaired. When thiamine (10 mu M) is added to the cells, t he O-2 consumption increases, respiratory control is restored, and nor mal cell and mitochondrial morphology is recovered within 1 h. Succina te, which is oxidized via the thiamine diphosphate-independent succina te dehydrogenase, is also able to restore a normal O-2 consumption (wi th respiratory control) in digitonin-permeabilized thiamine-deficient cells. Our results therefore suggest that the slowing of the citric ac id cycle is the main cause of the biochemical lesion induced by thiami ne deficiency as observed in Wernicke's encephalopathy.