CHRONIC HALOPERIDOL POTENTIATES STIMULATED GLUTAMATE RELEASE IN CAUDATE-PUTAMEN, BUT NOT PREFRONTAL CORTEX

RATS were given haloperidol continuously for 6 months via subcutaneous implants. Extracellular concentrations of basal and high K+-stimulate d GABA and glutamate in the lateral caudate putamen and the medial pre frontal cortex were then assessed using microdialysis. While there wer e no significant differences in basal extracellular concentrations in either brain region, chronic haloperidol-treated rats showed significa ntly greater increases in glutamate following stimulation with high K in the caudate putamen, but not the prefrontal cortex. This effect wa s accompanied by an attenuation of K+-stimulated GABA overflow in the caudate putamen. These results suggest regionally selective alteration s in amino acid transmitter function which may be related to chronic n euroleptic-induced motor side effects.