Objective To examine the effect of acetylcholine（ACh）on the electric activities of pain-excitation neurons （PEN）and pain-inhibitation neurons（PIN）in the hippocampal CA1 area of normal rats or morphinistic rats,a...
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Objective To examine the effect of acetylcholine（ACh）on the electric activities of pain-excitation neurons （PEN）and pain-inhibitation neurons（PIN）in the hippocampal CA1 area of normal rats or morphinistic rats,and to explore the role of ACh in regulation of pain perception in CA1 area under normal condition and morphine *** The trains of electric impulses applied to sciatic nerve were set as noxious *** discharges of PEN and PIN in the CA l area were recorded extracellularly by glass *** observed the influence of intracerebroventricular （i.c.v.）injection of ACh and atropine on the noxious stimulation-evoked activities of PEN and PIN in the CA1 *** Noxious stimulation enhanced the electric activity of PEN and depressed that of PIN in the CA1 area of both normal and addiction *** normal rats,ACh decrease the pain-evoked discharge frequency of PEN,while increased the frequency of *** effects reached the peak value at 4 min after injection of *** morphinistic rats,ACh also inhibited the PEN electric activity and potentialized the PIN electric activity,but the maximum effect appeared at 6 min after administration. The ACh-induced responses were significantly blocked by muscarinic receptor antagonist *** Cholinergic neurons and muscarinic receptors in the hippocampal CA1 area are involved in the processing of nociceptive information and they may play an analgesia role in pain *** addiction attenuated the sensitivity of painrelated neurons to the noxious information.
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 influen...
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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. Conclusion The responses to painful stimulation were completely opposite between normal rats and morphinistic rats after the intracerebroventricular injection of DA.
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