EVIDENCE FOR SENSITIZATION OF COCAINE-INDUCED NUCLEUS-ACCUMBENS GLUTAMATE RELEASE

COCAINE-stimulated glutamate release in the nucleus accumbens was stud ied following chronic cocaine or saline pretreatment in order to deter mine whether this effect was sensitized in rats showing augmented dopa mine release, locomotor and stereotypy responses. Rats were pretreated with cocaine (30 mg kg(-1)) or saline for 5 consecutive days and were tested with cocaine (15 mg kg(-1)) after a 10-day withdrawal period. Cocaine-induced glutamate release, dopamine release, horizontal locomo tor activity and stereotypy were monitored simultaneously in animals u ndergoing in vivo microdialysis in the nucleus accumbens. The basal le vels of extracellular glutamate and dopamine, as well as locomotor act ivity, were not different between cocaine- and saline-pretreated group s. Following cocaine injection the increase in glutamate release, dopa mine release, locomotor activity and stereotypy were greater in the co caine-pretreated animals. These results show that cocaine-stimulated g lutamate release in the nucleus accumbens is sensitized following chro nic cocaine pretreatment.