Studies on the possible role of thiamine in the central nervous system

Thiamine, in the form of its diphosphate (TDP), is well known to act as a coenzyme, and during the early stage in the study of thiamine it had been believed that the symptoms of thiamine-deficiency were resulted secondarily from the disturbance of metabolic processes in which TDP participated as a coenzyme. However, the neurological symptoms in thiamine deficiency are now separated from the metabolic disturbances in thiamine deficiency. On the other hand, the specific involvement of phosphorylated thiamine in nerve conduction has been suggested by von Muralt, but nature of this involvement has not been elucidated at a molecular level. Recently the possible significance of thiamine triphosphate (TTP) in nervous tissue was suggested by the demonstration that TTP is not present in the brain of patients with subacute necrotizing encephalomyelitis, a fatal disease associated with an abnormality in thiamine metabolism. Furthermore, the studies using membrane fragments of rat brain strongly indicated that ion movement across the nerve membrane is associated with dephosphorylation of phosphorylated thiamine.