Distribution of thiamine phosphate esters in normal and thiamine-deficient brain

Experiments were undertaken to determine whether depletion of thiamine phosphate esters occurs in a selective manner in portions of rat brain which are known to be most vulnerable to thiamine deprivation, namely, the pons and midbrain. We found that total thiamine in the brain diminished in all regions over the course of the study, which comprised 9 weeks on a thiamine-deficient diet; however, the pattern of diminution of thiamine phosphate esters varied. In cerebral cortex and cerebellum, nearly normal proportions of thiamine phosphate esters were maintained throughout depletion. In contrast, thiamine pyrophosphate became markedly depleted proportionately in the pons and midbrain. A striking proportionate increment in thiamine triphosphate was noted in these regions. Both changes tended to be most marked in animals showing more severe clinical signs of depletion.