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Role of Dendritic Dopamine of the Substantia Nigra in the Modulation of Nigrocollicular γ‐Aminobutyric Acid Release: In Vivo Studies in the Rat
Author(s) -
Le Boulch N. Lantin,
TruongNgoc N. A.,
Gauchy C.
Publication year - 1991
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.1471-4159.1991.tb08261.x
Subject(s) - substantia nigra , dopamine , in vivo , neuroscience , chemistry , aminobutyric acid , neurotransmitter , pharmacology , biochemistry , biology , central nervous system , dopaminergic , receptor , microbiology and biotechnology
The release of γ‐[ 3 H]aminobutyric acid ([ 3 H]GABA) newly synthesized from [ 3 H]glutamine was estimated in the superior colliculus of ketamine‐anesthetized rats superfused via a push‐pull cannula. A significant amount of [ 3 H]GABA was spontaneously released in the superior colliculus (582 ± 49 pCi/10 min). A major part of the large K + ‐evoked increase of the [ 3 H]GABA release was Ca 2+ dependent. When neuronal activity of the substantia nigra was enhanced by nigral application of K + (30 m M ) or bicuculline (10– 4 M ), a persistent increase of the collicular [ 3 H]GABA release was observed (60 and 80%, respectively). Conversely, when nigral activity was reduced by nigral application of GABA (10– 4 M ) or superfusion with a Ca 2+ free medium, a sustained decrease of the collicular [ 3 H]GABA release was observed (‐30 and ‐40%. respectively). Following the nigral application of a selective D 2 ‐receptor agonist, RU 24926 (10– 5 M ), for 30 min in 6‐hydroxydopamine‐lesioned rats, a phasic increase (60%) of the collicular [ 3 H]GABA release was detected. This effect could result from an activation of nigrocollicular GABAergic neurons by D 2 ‐receptor stimulation, because nigral activity and collicular release of [ 3 H]GABA changed in a parallel direction.