Cerebral endothelial GABA-T activity: effects of in vivo GABA-T inhibition.

The effects of gamma-aminobutyric acid transaminase (GABA-T) inhibitors on rat endothelial GABA-T activity has been studied utilizing a modified tetrazolium salt histochemical technique. Blue-diformazan staining of cerebrovascular and parenchymal sites of GABA catabolism in normal brain was almost completely prevented in unfixed frozen brain sections from rats subjected to 'in vivo' GABA-T inhibition using aminooxyacetic acid or gabaculine. These results provide histochemical evidence for the efficacy of using systemically administered GABA-T inhibitors to inhibit endothelial GABA-T activity.