| Objective：On the basis of the successful morphinistic rats model, the presentstudy aimed to determine the effect of acetylcholine(ACh), muscarinic ACh receptors(mAChRs) agonist pilocarpine and mAChRs antagonist atropine on the pain-evokedresponses of the pain-related electric activities in the hippocampal CA3of normalrats.Methods：Use the exacellular electrophysiological recording techniques, thepresent study explored the effect of ACh, pilocarpine and atropine on the pain-evokedresponses of the pain-related electric activities in the hippocampal CA3of normal andmorphinistic rats.Results：(1) There exist pain-excited neurons (PEN) and pain-inhibited neurons(PIN) in the hippocampal CA3of normal and morphinistic rats.(2) ACh orpilocarpine inhibited the electric activities of evoked discharges of PEN andpotentiated those of PIN in the hippocampal CA3of normal rats, and atropinepotentiated the electric activities of evoked discharges of PEN and simultaneouslyinhibited those of PIN in the hippocampal CA3of normal rats.(3) The effect of thecholiergic substance on the pain-related neurons in the hippocampal CA3ofmorphinistic rats is same as the rats in control group. However, the maximum effectsof the choliergic substance were2~4minutes later than the control group.Conclusion： Cholinergic material and hippocampal CA3of normal andmorphinistic rats are involved in the modulation of nociceptive response. ACh canreduce the excitabilities of PEN and potentiate that of PIN in the hippocampal CA3ofnormal and morphinistic rats. Morphine-addiction reduced the sensitivity of the pain-related neurons to the nociceptive stimulation in the hippocampal CA3. |
