Specificity of GABA as a stimulator of dopamine release in rat substantia nigra.
The effects of amino acids and the benzodiazepine, flurazepam, on spontaneous and potassium-stimulated [3H]dopamine (DA) release were studied in slices of rat substantia nigra. None of the amino acids tested liberated [3H]DA directly. Flurazepam increased [3H]DA output by 51% and this effect was partially blocked by bicuculline but not by picrotoxin. GABA, L-glutamate and flurazepam, but none of the other compounds, potentiated the release of [3H]DA evoked by 20 mM KCl. The facilitation produced by flurazepam, but not by GABA or L-glutamate, was weakly antagonized by bicuculline and not picrotoxin. GABA did not modify the efflux of [3H]DA induced by low Na+, veratridine, ouabain, calcium ionophore A 23187, amphetamine or exogenous DA.
D000596:Amino Acids / Q000494:pharmacology; D000818:Animals; D004298:Dopamine / Q000378:metabolism*; D005479:Flurazepam / Q000494:pharmacology; D005971:Glutamates / Q000494:pharmacology; D018698:Glutamic Acid; D066298:In Vitro Techniques; D008297:Male; D010852:Picrotoxin / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012964:Sodium / Q000494:pharmacology; D013329:Structure-Activity Relationship; D013378:Substantia Nigra / Q000187:drug effects / Q000378:metabolism*; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology*
D000596:Amino Acids; D004298:Dopamine; D005479:Flurazepam; D005971:Glutamates; D018698:Glutamic Acid; D010852:Picrotoxin; D011188:Potassium; D012964:Sodium; D005680:gamma-Aminobutyric Acid