Further contribution to the study of corticostriatal glutamatergic and nigrostriatal dopaminergic interactions within the striatal network: an in vivo voltammetric investigation.

In vivo voltammetry was used in freely moving rats to study the processes whereby striatal dopamine (DA) release is regulated by corticostriatal glutamatergic neurons. Electrical stimulation of the cerebral cortex was found to markedly increase the striatal DA-related voltammetric signal amplitude. Similar enhancements have been observed after intracerebroventricular administration of 10nmoles glutamate, quisqualate and AMPA, whereas NMDA was found to decrease the amplitude of the striatal signals. The NMDA receptor antagonist APV did not significantly affect the voltammetric signal but prevented the NMDA-induced depression of the DA-related signals. These data are in agreement with those obtained in numerous previous studies suggesting that the glutamatergic corticostriatal neurons exert activatory effects on the striatal DA release via non-NMDA receptors. The mechanism involved might be of a presynaptic nature. The role of the NMDA receptors may however consist of modulating the dopaminergic transmission phasically and in a depressive way, which would be consistent with behavioural data suggesting the existence of a functional antagonism between the activity of the corticostriatal glutamatergic and nigrostriatal dopaminergic systems.