Relevance of GABA in the nigrostriatal system.
In conclusion, even though the mutual integration of intrastriatal circuits remains an open question, the electrophysiological and neurochemical approaches seem to provide valid support toward understanding the complexity of these systems. Recent findings seem to indicate that, besides a dopaminergic and cholinergic link, interactions between DA and GABA neurons may be operative within the striatum. An understanding of these functional interplays may facilitate future attempts aimed at clarifying the electrophysiological discrepancies concerning the inhibitory or excitatory action of DA on the target cells in this brain structure. Studies on the functional roles of pathways projecting from striatum to substantia nigra have indicated that these may be implicated in the regulation of nigral efferents to other brain nuclei and that they do control striatal DA activity through feedback mechanisms.