Differential effects of dopamine on pain-related electric activities in normal rats and morphinistic rats.
OBJECTIVE
To investigate the influence of dopamine (DA) and DA receptor's antagonist on the transmission of noxious information in the central nervous system of normal rats or morphinistic rats.


METHODS
The influence of DA on the electric activity of the pain-excited neuron (PEN) in the caudate nucleus (Cd) of normal rats or morphinistic rats was recorded after the sciatic nerve was noxiously stimulated.


RESULTS
DA shortened the average latency of the evoked discharge of PEN in the Cd of normal rats, indicating that DA could increase the activity of PEN and pain sensitivity in normal rats. This effect could be inhibited by Droperidol. DA increased the average latency of the evoked discharge of PEN in the Cd of morphinistic rats, indicating that DA could inhibit the activity of PEN and pain sensitivity in morphinistic rats.


CONCLUSIONS
The responses to painful stimulation were completely opposite between normal rats and morphinistic rats after the intracerebroventricular injection of DA.
Zhang
Ying
Y
Department of Physiology, Harbin Medical University, Harbin 150081, China.
Xu
Man-Ying
MY
Su
Jie
J
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D000704:Analysis of Variance; D000818:Animals; D002421:Caudate Nucleus / Q000187:drug effects; D004195:Disease Models, Animal; D004298:Dopamine / Q000494:pharmacology*; D018492:Dopamine Antagonists / Q000494:pharmacology; D004329:Droperidol / Q000494:pharmacology; D004347:Drug Interactions; D004558:Electric Stimulation / Q000009:adverse effects; D005260:Female; D008297:Male; D009021:Morphine Dependence / Q000503:physiopathology* / Q000628:therapy; D009474:Neurons / Q000187:drug effects*; D010146:Pain / Q000188:drug therapy / Q000209:etiology / Q000503:physiopathology*; D017288:Pain Threshold / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects
D018492:Dopamine Antagonists; D004329:Droperidol; D004298:Dopamine