Metabolism of thiamin and its phosphoric esters in different regions of the nervous system: a new approach.

In the nervous system thiamin could have two main functions: coenzymatic, as thiamin pyrophosphate, and/or non-coenzymatic, but related to the nervous activity. In order to investigate the thiamin role we studied the turnover and metabolism of thiamin and its phosphoesters (mono-, pyro-, and tri-phosphate) in different regions (cerebellum, brain stem, cerebral cortex and sciatic nerve) of the nervous system, in a steady state condition. Practically, we determined the regional radioactivity of thiamin and its phosphoesters at different times (up to 240 hrs) from labeled thiamin administration, analyzing the obtained data by suitable compartmental models. From the results of two different types of experiment and from their mathematical elaboration, the cerebellum, with the highest thiamin compound content, appeared to be the most active region of the brain in different steps of thiamin metabolism (phosphorylation, dephosphorylation, uptake and release). The sciatic nerve, however, stood out for only thiamin and thiamin monophosphate metabolism, in spite of its very low total thiamin content.