CHRONIC ADMINISTRATION OF VALPROIC ACID INDUCES A DECREASE IN RAT STRIATAL GLUTAMATE AND TAURINE LEVELS

The effect of acute and chronic (10 days) administration of 200 mg/kg (i.p.) of valproic acid (VPA) on endogenous levels of aspartate, gluta mate, alanine, glycine and taurine in the cerebral frontal cortex and corpus striatum of rats was studied. Quantification of the amino acid levels was performed by HPLC. Valproic acid (VPA) did not either induc e changes on these neurotransmitters contents in corpus striatum after acute treatment. After chronic administration we found a decrease on the endogenous levels of glutamic acid (24%, p < 0.05) which was relat ed to an increase (250%, p < 0.02) of the in vitro KCl evoked release of glutamate. We found decrements in taurine endogenous levels (22%, p < 0.05) which was not associated with an increase of its release. In cerebral frontal cortex there was not found any change neither under t he acute nor under the chronic condition. Thus, it may be conclude tha t chronic treatment with VPA produces decreases on the endogenous leve ls of glutamate and taurine. However the relevance of this effect conc erning it therapeutic action remains unclear.