Striatal dopamine-glutamate interactions reflected in substantia nigra reticulata firing

To gain insight into the role of striatal dopamine in basal ganglia functio ning, dopaminergic drugs alone and in combination with the glutamate recept or agonist kainic acid were infused in the lateral striatum via a microdial ysis probe, while single-unit recordings of substantia nigra reticulata neu rons were made in chloral hydrate-anaesthetized rats. Striatal infusion of dopaminergic drugs did not significantly affect the firing rate of substant ia nigra reticulata neurons, which was related to the low activity of stria tal cells under basal conditions, illustrated by the lack of effect of stri atal infusion of TTX on substantia nigra reticulata activity. Under glutama te;stimulated conditions, striatal infusion of d-amphetamine potentiated th e inhibition of substantia nigra reticulata neurons induced by striatal kai nic acid. Thus, under stimulated but not basal conditions, the modulatory r ole of dopamine in the striatum could be demonstrated. Dopamine potentiated the inhibitory effect of striatal kainic acid on the firing rate of the ba sal ganglia output neurons. NeuroReport 9: 3829-3836 (C) 1998 Lippincott Wi lliams & Wilkins.