title: GABAergic nerve terminals decrease in the substantia nigra following hemitransections of the striatonigral and pallidonigral pathways.
abstract: Glutamic acid decarboxylase (GAD), the enzyme that synthesizes the neurotransmitter, GABA, was immunocytochemically localized in axon terminals as well as in small and medium-sized neurons of the rat substantia nigra. The pattern formed by GAD-containing axon terminals with the dendrites and somata of neurons in the substantia nigra was altered following ipsilateral hemitransections of the striatonigral and pallidonigral pathways. A marked reduction of GAD-positive terminals occurred throughout this brain region, but the ventral fifth of the pars reticulata showed a nearly normal pattern of GAD-positive axon terminals. The results of this investigation are consistent with results from biochemical studies which have indicated that the striatonigral and/or pallidonigral pathways are GABAergic. In addition, these results suggest that the residual GABAergic terminals remaining after hemitransection are derived from intrinsic neurons of the substantia nigra.
mesh_terms: D000818:Animals; D001369:Axons / Q000201:enzymology; D003342:Corpus Striatum / Q000033:anatomy & histology / Q000201:enzymology*; D003712:Dendrites / Q000201:enzymology; D005917:Globus Pallidus / Q000033:anatomy & histology / Q000201:enzymology*; D005968:Glutamate Decarboxylase / Q000378:metabolism; D009434:Neural Pathways / Q000033:anatomy & histology / Q000201:enzymology; D051381:Rats; D013378:Substantia Nigra / Q000033:anatomy & histology / Q000201:enzymology*; D013569:Synapses / Q000201:enzymology; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
chemical_list: D005680:gamma-Aminobutyric Acid; D005968:Glutamate Decarboxylase