Endogenous dopamine increases extracellular concentrations of glutamate and GABA in striatum of the freely moving rat: Involvement of D1 and D2 dopamine receptors

Interactions between endogenous dopamine, glutamate, GABA, and taurine were investigated in striatum of the freely moving rat by using microdialysis. Intrastriatal infusions of the selective dopamine uptake inhibitor nomifens ine (NMF) were used to increase the endogenous extracellular dopamine. NMF produced a dose-related increase in extracellular dopamine and also increas ed extracellular concentrations of glutamate, GABA, and taurine. Extracellu lar increases of dopamine were significantly correlated with extracellular increases of glutamate and GABA, but not taurine. To investigate whether th e increased extracellular dopamine produced by NMF was responsible for the concomitant increase of glutamate and GABA, D1, and D2 receptor antagonists were used. Dopamine receptor antagonists D1 (SCH23390) and D2 (sulpiride) significantly attenuated the increases of glutamate and GABA produced by NM F. These data suggest that endogenous dopamine, through both D1 and D2 dopa mine receptors, plays a role in releasing glutamate and GABA in striatum of the freely moving rat.