The action of dopamine on rat caudate neurones intracellularly recorded.

The action of dopamine (DA) was studied on rat striatal neurones monosynaptically activated by the substantia nigra (SN) or the medial forebrain bundle (MFB) stimulation. DA, iontophoretically applied, slowly depolarized the membrane cell and decreased the firing rate. The membrane resistance was not modified during DA ejection. Short pulses (up to 300 msec) of DA had no effect on the neurone. These findings suggest that DA is not the fast excitatory transmitter of the nigro-striatum projection, but it plays a different role in this pathway.