In this study, we investigated whether the expression of pyridoxal kinase (PLK) and pyridoxine-5'-phosphate oxidase (PNPO) are altered following long-term potentiation (LTP) induction, and whether Tat-PLK and Tat-PNPO transductions affect LTP induction and paired-pulse responses in the rat dentate gyrus (DG). PNPO immunoreactivity was markedly increased in dentate granule cells after the induction of LTP, but that of PLK was not. Tat-PNPO (20 and 200 microg/kg), but not Tat-PLK or vitamin B6 precursors, treatments, increased the efficiency of high frequency stimulus-induced potentiation of populations spike amplitude when compared with saline-, or Tat-protein-treated animals. These changes correlated with the alterations in PNPO activity and its immunoreactivity. In addition, Tat-PNPO transduction increased paired-pulse facilitation but had no effect on the fast and late paired-pulse inhibitions. These findings suggest that PNPO may play a role in activity-dependent regulation of PLP level in the brain, which is involved in LTP induction and paired-pulse facilitation but not in enhancement of GABAergic inhibition.
Copyright 2008 Wiley-Liss, Inc.