Taurine-like GABA aminotransferase inhibitors prevent rabbit brain slices against oxygen-glucose deprivation-induced damage

The activation of the GABAergic system has been shown to protect brain tissues against the damage that occurs after cerebral ischaemia. On the other hand, the taurine analogues (+/-)Piperidine-3-sulphonic- (PSA), 2-aminoethane phosphonic- (AEP), 2-(-acetylamino) cyclohexane sulfonic-acids (ATAHS) and 2-aminobenzene sulfonate-acids (ANSA) have been reported to block GABA metabolism by inhibiting rabbit brain GABA aminotransferase and to increase GABA content in rabbit brain slices. The present investigation explored the neuroprotection provided by GABA, Vigabatrin (VIGA) and taurine analogues in the course of oxygen-glucose deprivation and reperfusion induced damage of rabbit brain slices. Tissue damage was assessed by measuring the release of glutamate and lactate dehydrogenase (LDH) during reperfusion and by determining final tissue water gain, measured as the index of cell swelling. GABA (30-300 mu M) and VIGA (30-300 mu M) significantly antagonised LDH and glutamate release, as well as tissue water gain caused by oxygen-glucose deprivation and reperfusion. Lower (1-10 mu M) or higher concentrations (up to 3,000 mu M) were ineffective. ANSA, PSA and ATAHS significantly reduced glutamate and LDH release and tissue water gain in a range of concentrations between 30 and 300 mu M. Lower (0-10 mu M) or higher (up to 3,000 mu M) concentrations were ineffective. Both mechanisms suggest hormetic ("U-shaped") effects. These results indicate that the GABAergic system activation performed directly by GABA or indirectly through GABA aminotransferase inhibition is a promising approach for protecting the brain against ischemia and reperfusion-induced damage.