The effect of dopamine on pain-related neurons in the parafascicular nucleus of rats.
Dopamine (DA) regulates pain perception in the central nervous system (CNS). However, the mechanism of the action of DA in pain-related neurons of the parafascicular nucleus (Pf) is not clear. The present study aimed to determine the effect of DA and its receptor antagonist, droperidol on the pain-evoked responses of the pain-excited neurons (PEN) and pain-inhibited neurons (PIN) in the Pf of rats and to analyze the mechanisms underlying this effect. The trains of electric impulses applied to the sciatic nerve were used as noxious stimulation. The discharges of PEN and PIN in the Pf were recorded by using a glass microelectrode. The results showed that, in the Pf, intra-Pf microinjection of DA (5 microg/0.5 microl) increased the frequency of noxious stimulation-induced discharges of the PEN and decreased the frequency of those of the PIN, while the intra-Pf administration of droperidol (0.15 microg/0.5 microl) produced an opposite effect. On the basis of the above-mentioned findings, we could conclude that DA and its receptors in the Pf are involved in the modulation of the nociceptive response by regulating the discharges of PEN and PIN.
Gao
H-R
HR
Laboratory of Neural Electrophysiology, Department of Physiology, Harbin Medical University, 194 Xuefu Road, Nangang District, Harbin, Heilongjiang 150081, China.
Shi
T-F
TF
Yang
C-X
CX
Zhang
D
D
Zhang
G-W
GW
Zhang
Y
Y
Jiao
R-S
RS
Zhang
H
H
Xu
M-Y
MY
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D004195:Disease Models, Animal; D004298:Dopamine / Q000378:metabolism* / Q000494:pharmacology; D018492:Dopamine Antagonists / Q000494:pharmacology; D004329:Droperidol / Q000494:pharmacology; D004558:Electric Stimulation / Q000379:methods; D005260:Female; D020646:Intralaminar Thalamic Nuclei / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D008845:Microinjections; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D009619:Nociceptors / Q000187:drug effects / Q000378:metabolism*; D010146:Pain / Q000378:metabolism* / Q000503:physiopathology; D010147:Pain Measurement / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D011954:Receptors, Dopamine / Q000187:drug effects; D012584:Sciatic Nerve / Q000503:physiopathology
D018492:Dopamine Antagonists; D011954:Receptors, Dopamine; D004329:Droperidol; D004298:Dopamine