[Reversal of the inhibitory effect of electroacupuncture on the nociceptive response of neurons in parafascicular nucleus by naloxone and atropine in acute arthritic rats].
Rats with adjuvant arthritis were used as an animal model of pathological pain in this experiment and the nociceptive response of neurons in parafascicular nucleus (Pf) were recorded and intracerebroventricular (icv) injection of naloxone and atropine was adopted in order to investigate the effect of electroacupuncture (EA) and to analyze the neurotransmitters involved. The main results were as follows: (1) The nociceptive response of the majority of Pf neurons (29/34) in arthritic rats was significantly inhibited by EA at acupoints of "Zusanli" and "Sanyinjiao"; (2) The inhibitory effect of EA was reversed in 12/13 units by icv injection of naloxone (4 micrograms/10 microliters); (3) The inhibitory effect of EA was also reversed in 11/12 units by icv injection of atropine (5 micrograms/10 microliters) (4) The spontaneous unit discharge of Pf neurons in arthritic rats was increased after icv injection of naloxone or atropine. Experimental results suggest that EA could have an inhibitory effect on the nociceptive response of Pf neurons in arthritic rats, which might be mediated by opioid system and cholinergic system in the brain, and that opioid system and cholinergic system might have a tonic inhibitory effect on the spontaneous unit discharge of Pf neurons in arthritic rats.
Laboratory of Neurobiology, Suzhou Medical College.
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Xu
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Duanmu
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Yin
D000818:Animals; D001169:Arthritis, Experimental / Q000503:physiopathology*; D001285:Atropine / Q000494:pharmacology; D015671:Electroacupuncture; D008297:Male; D009270:Naloxone / Q000494:pharmacology*; D009474:Neurons / Q000502:physiology; D009619:Nociceptors / Q000503:physiopathology*; D051381:Rats; D017208:Rats, Wistar; D013787:Thalamic Nuclei / Q000502:physiology*
D009270:Naloxone; D001285:Atropine