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Neurochemical Studies of the Mesolimbic Dopaminergic Pathway: Somatodendritic Mechanisms and GABAergic Neurones in the Rat Ventral Tegmentum
Author(s) -
Beart P. M.,
McDonald Danielle
Publication year - 1980
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1980.tb11253.x
Subject(s) - dopamine , tegmentum , dopaminergic , nucleus accumbens , substantia nigra , chemistry , medicine , ventral tegmental area , endocrinology , gabaergic , neuroscience , biology , inhibitory postsynaptic potential , midbrain , central nervous system
The rat ventral tegmentum (containing dendrites and somata of mesolimbic neurones) contained 1.3 μg/g of dopamine, which was reduced to 40% of the control level by reserpine. Slices of ventral tegmentum were able to accumulate and release (elevated potassium or protoveratrine A) exogenous [ 3 H]dopamine. In parallel studies the uptake mechanism in ventral tegmentum was shown to be virtually identical to the nerve terminal uptake of [ 3 H]dopamine by slices of nucleus accumbens. The release of [ 3 H]dopamine was indistinguishable from that observed in substantia nigra, where there is substantial evidence for dendritic mechanisms. Basal adenylate cyclase activity was present, but dopamine‐stimulated activity was not detected. A high GABA concentration (7.7 μmol/g) was present in ventral tegmentum, in conjunction with an uptake and a release mechanism for [ 3 H]GABA. GABA and muscimol elicited a small, reproducible efflux of [ 3 H]dopamine, but an interaction between dopamine and [ 3 H]GABA efflux was not observed. The results are in accord with transmitter roles for dopamine and GABA in the somatoden‐dritic area of mesolimbic dopaminergic neurons.