Effects of acute and chronic ethanol administration on regional thiamin pyrophosphokinase activity of the rat brain.

Thiamin pyrophosphokinase (TPKase) activity was determined in supernatants of cerebral cortex, cerebellum, pons, medulla, hypothalamus and corpus callosum homogenates obtained from normal rats and from rats given ethanol acutely (a single dose of 4.7 g X kg-1 body wt) or chronically (4.7 g X kg-1 body wt daily for 35 days) by gastric gavage. Regional cell densities (derived from DNA content) and protein contents were also determined. TPKase was detected in all brain regions investigated, the highest activity being found in the cerebellum or in the pons depending on whether it was expressed per mg of protein or per number of cells, respectively. In samples taken following acute ethanol administration protein content was unaffected, while TPKase activity was significantly reduced in the cerebellum, cerebral cortex and hypothalamus at 90 min and in the cerebellum and cerebral cortex at 300 min. Chronic ethanol intake was associated with a significant decrease in regional cell densities, protein contents and TPKase activity. The addition of ethanol to the incubation medium of normal tissue supernatant caused a dose-dependent inhibition of TPKase activity. These results suggest that ethanol markedly impairs thiamin cellular utilization, which may result in depression of brain metabolism.