Presynaptic D2 dopaminergic receptors mediate inhibition of excitatory synaptic transmission in rat neostriatum.
The effect of dopamine (DA) on excitatory synaptic transmission was studied in rat neostriatal neurons using intracellular- and whole-cell voltage clamp-recording methods. Depolarizing excitatory postsynaptic potentials (EPSPs) were evoked by cortical stimulation. Superfusion of DA (0.01-10 microM) reversibly decreases EPSP in a concentration-dependent manner and with a estimated IC50 of 0.3 microM. In addition, the inhibitory effect induced by DA at a low concentration (0.1 microM) was antagonized by sulpiride (1-10 nM), a selective D2 dopaminergic receptor antagonist. However, D1 dopaminergic receptor antagonist SKF-83566 (1-5 microM) did not affect the blocking effect by DA 0.1 microM. Based on these findings, we conclude that DA at a low concentration (< or = 0.1 microM) reduced the excitatory response of neostriatal neurons following cortical stimulation via the activation of D2, but not D1 dopaminergic receptors, located on the terminals of corticostriatal neurons.
Department of Pharmacology, College of Medicine, National Cheng-Kung University, Tainan, Taiwan.
K S
KS
Hsu
C C
CC
Huang
C H
CH
Yang
P W
PW
Gean
D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D002540:Cerebral Cortex / Q000502:physiology; D004298:Dopamine / Q000494:pharmacology*; D018492:Dopamine Antagonists / Q000494:pharmacology; D004558:Electric Stimulation; D005071:Evoked Potentials / Q000187:drug effects; D066298:In Vitro Techniques; D017072:Neostriatum / Q000166:cytology / Q000187:drug effects*; D009474:Neurons / Q000187:drug effects*; D018408:Patch-Clamp Techniques; D051381:Rats; D017207:Rats, Sprague-Dawley; D017448:Receptors, Dopamine D2 / Q000187:drug effects*; D017661:Receptors, Presynaptic / Q000187:drug effects*; D013469:Sulpiride / Q000494:pharmacology; D009435:Synaptic Transmission / Q000187:drug effects*
D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine; D004298:Dopamine; D018492:Dopamine Antagonists; D017448:Receptors, Dopamine D2; D017661:Receptors, Presynaptic; D013469:Sulpiride; C044846:SKF83566