Synaptosomal uptake and release of dopamine in substantia nigra: effects of gamma-aminobutyric acid and substance P.
Nigral tissue prepared as synaptosomes demonstrates both high and low affinity uptake of [3H]dopamine. Recently accumulated [3H]dopamine is releasable by 35 mN K+. Substance P increases both uptake and release of dopamine by nigral synaptosomes; gamma-aminobutyric acid (GABA) inhibits release with no effect on uptake at concentrations less than 10-(4) M. In the striatum, substance P inhibits both uptake and release of dopamine. The results support the existence of dopamine-containing terminals in substantia nigra tissue. The differences in response to substance P and GABA found between nigra and striatum may reflect structural differences in dopamine-containing processes in these areas, related to their proposed origin as dendtritic (substantia nigra) and axonal (striatal) terminal.
D000818:Animals; D003342:Corpus Striatum / Q000378:metabolism; D004298:Dopamine / Q000378:metabolism*; D007700:Kinetics; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D013373:Substance P / Q000494:pharmacology*; D013378:Substantia Nigra / Q000187:drug effects / Q000378:metabolism*; D013574:Synaptosomes / Q000378:metabolism; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology*
D013373:Substance P; D005680:gamma-Aminobutyric Acid; D011188:Potassium; D004298:Dopamine