Kynurenic acid: a new effector of valproate action?

We investigated the changes in hippocampal kynurenic acid (KYNA) concentrations and the amino acids involved in neuronal activity regulation following valproate (VPA) administration (400 mg/kg ip) in pentylenetetrazole-kindled rats (in vivo). We found a remarkably long-lasting increase in KYNA levels following VPA administration, and this effect correlated with a rise in GABA levels. No changes in the concentration of other analyzed amino acids were present. It is likely that the antiepileptic and neuroprotective properties of VPA may also be a consequence of an increase in the hippocampal KYNA concentration.