A POSSIBLE INHIBITORY-ACTION OF BACLOFEN ON HIPPOCAMPUS GABAERGIC NEURONS

1. The function of the gamma-aminobutyric acid (GABA)ergic system in c ertain areas of the rat brain was investigated after baclofen treatmen t (30 mg/kg for 4 days). 2. Two h after the last dose of baclofen GAD activity was reduced in the hippocampus without changes in GABA levels . 24 h after baclofen, GAD activity was increased and the GABA content was decreased. 3. 48 h after the last dose both parameters returned t o control values. 4. These results were not observed in any of the oth er areas investigated: frontal cerebral cortex, corpus striatum, olfac tory bulbs, and medio basal hypothalamus. 5. In conclusion, the presen t study shows that baclofen 30 mg/kg for 4 days, induces an inhibitory action on hippocampus GABAergic neurones, which begins to disappear a fter 24 h free of drug.