Localization of GABAergic, cholinergic and aminergic structures in the mesolimbic system

Fonnum, F.; Walaas, I.; Iversen, E.

Journal of Neurochemistry 29(2): 221-230

1977


ISSN/ISBN: 0022-3042
PMID: 301925
DOI: 10.1111/j.1471-4159.1977.tb09612.x
Accession: 068525662

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Abstract
The localization of cholinergic, GABAergic and aminergic structures in the mesolimbic system was discussed from studies on the topographical distribution of choline acetyltransferase, glutamate decarboxylase and aromatic amino acid decarboxylase in normal rat brain and in brains hemitransected at the level of globus pallidus. The structures analyzed included nucleus accumbens, olfactory tubercle, septum, medial forebrain bundle, striatum, substantia nira, ventral tegmental area and nucleus interpeduncularis. Choline acetyltransferase was highly concentrated in the nucleus interpeduncularis, but it also exhibited considerable activity in the nucleus accumbens, the olfactory tubercle and the striatum. The activities did not change after hemitransection. Aromatic amino acid decarboxylase was highly concentrated in the ventral tegmental area, but high activities were also found in the striatum, the nucleus accumbens, the olfactory tubercle and the pars compacta of the substantia nigra. The activity decreased in all areas rostral to the hemitransection. Glutamate decarboxylase was highly concentrated in the dopamine innervated regions, more so in the limbic structures than in the striatum. Much higher activity was found in the substantia nigra than in the ventral tegmental area. After hemitransection the activity in the substantia nigra was decreased whereas in the ventral tegmental area it was unchanged. Apparently dopaminergic cells in the ventral tegmental area do not receive GABAergic fibers from the terminal regions of the ascending dopaminergic fibers. In addition, there was a very high concentration of glutamate decarboxylase in a region traversed by the rostral medial forebrain bundle. Here the activity was mainly confined to the particulate fraction, probably the synaptosomes. This fraction also displayed a very active high affinity uptake of GABA.