[Effect of ATP-sensitive K+ channel blocker (quinine) on the dopamine decrease induced by selective D3 agonist (7-OH-DPAT) in the rat striatum].
In vivo brain microdialysis was used to investigate the role of D3 receptors relating to dopamine auto-regulated systems in the rat. A local infusion of the dopamine D3 selective agonist, 7-OH-DPAT (100 nM), into the striatum through the dialysis membrane produced a significant decrease in extracellular concentrations of dopamine. A local application of ATP-sensitive K+ (KATP) channel blocker, quinine (10 microM, 100 microM, 1 mM), produced dose-dependent increases in extracellular concentrations of dopamine. Quinine (100 microM, 1 mM) significantly blocked a 7-OH-DPAT-induced decrease in the striatal dopamine levels in the dose-dependent manner. Because of many previous reports, the autoregulated functions of dopamine release by D3 receptors in the striatum can be regarded mainly as nerve terminal autoreceptors and/or a short-loop negative feedback system. Therefore these results suggest that KATP channels may be present in nigrostriatal dopaminergic terminals and that in the striatum, presynaptic dopamine D3 autoreceptors and/or a post-synaptic D3 related short-loop negative feedback system inhibit dopamine release tonically by the activation of KATP channels.
Shimizu
K
K
Department of Psychiatry, National Defense Medical College, 3-2, Namiki, Tokorozawa, 359-8513 Japan.
Watanabe
M
M
Kodama
Y
Y
Hagino
Y
Y
Ogasawara
T
T
Nomura
S
S
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D003342:Corpus Striatum / Q000737:chemistry / Q000187:drug effects*; D004298:Dopamine / Q000032:analysis*; D018491:Dopamine Agonists / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D017551:Microdialysis; D015221:Potassium Channels / Q000187:drug effects*; D011803:Quinine / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D013764:Tetrahydronaphthalenes / Q000008:administration & dosage / Q000494:pharmacology*
D018491:Dopamine Agonists; D015221:Potassium Channels; D013764:Tetrahydronaphthalenes; D000255:Adenosine Triphosphate; D011803:Quinine; C031349:7-hydroxy-2-N,N-dipropylaminotetralin; D004298:Dopamine