Indirect presynaptic modulation of striatal dopamine release by GABA(B) receptors in the rat substantia nigra.
Regulation of striatal dopamine release by gamma-aminobutyric acid (GABA) neurotransmission was investigated using voltammetry in freely moving rats, following focal injection of the GABA(B) receptor agonist baclofen or the GABA(B) receptor antagonist 5-aminovaleric acid (5-AVA) in either the substantia nigra pars reticulata (SNr) or the substantia nigra pars compacta (SNc). Administration in the SNr of baclofen and 5-AVA at the dose of 2 pg, but not of 0.2 pg, resulted in a decrease and an increase in striatal dopamine release, respectively. In contrast, when injected in the SNc, 5-AVA only produced a transient increase in striatal dopamine release, while baclofen remained ineffective. This suggests that GABA(B) receptors in the SNr, but not the SNc, may play a major role in the control of nigrostriatal dopamine (DA) activity and the release of DA in the striatum.
Balon
Norbert
N
Université de la Méditerranée et IMNSSA, E.A. 3280, Laboratoire de Physiopathologie et Action Thérapeutique des Gaz sous Pression, Faculté de Médecine Nord, IFR Jean Roche, 13916 Marseille Cedex 20, France.
Kriem
Badreddine
B
Weiss
Michel
M
Rostain
Jean-Claude
JC
D021542:Amino Acids, Neutral / Q000494:pharmacology; D000818:Animals; D001418:Baclofen / Q000494:pharmacology; D003342:Corpus Striatum / Q000378:metabolism*; D004298:Dopamine / Q000378:metabolism*; D004594:Electrophysiology; D018755:GABA Agonists / Q000494:pharmacology; D018756:GABA Antagonists / Q000494:pharmacology; D058786:GABA-B Receptor Agonists; D008297:Male; D017729:Presynaptic Terminals / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D018080:Receptors, GABA-B / Q000502:physiology*; D013378:Substantia Nigra / Q000378:metabolism*
D021542:Amino Acids, Neutral; D018755:GABA Agonists; D018756:GABA Antagonists; D058786:GABA-B Receptor Agonists; D018080:Receptors, GABA-B; C013809:5-aminovaleric acid; D001418:Baclofen; D004298:Dopamine