Effect of sensory stimuli on the activity of dopaminergic neurons: Involvement of non-dopaminergic nigral neurons and striato-nigral pathways

Abstract

Single unit recording techniques were used to study the effects of sciatic nerve stimulation on the activity of dopaminergic and non-dopaminergic neurons in the rat substantia nigra. The stimulation-induced changes in zona compacta dopaminergic neuron activity usually consisted of an initial inhibitory period followed by one or more oscillations between excitation and inhibition. These oscillations were attenuated by parenterally administered haloperidol or by a lesion which destroyed striato-nigral pathways. The initial inhibitory period was decreased by haloperidol and increased by the lesion. Non-dopaminergic zona reticulata neurons responded to stimulation with an initial excitation which had a latency similar to the latency of the initial inhibition of dopaminergic neurons. These results, when combined with previously published data, suggest that sensory stimuli may induce an initial inhibition of dopaminergic neurons, at least in part, through excitation of an inhibitory non-dopaminergic zona reticulata neuron. The subsequent oscillations appear to be mediated through reciprocal striato-nigral, nigro-striatal pathways.