Electroacupuncture Effects in a Rat Model of Complete Freund’s Adjuvant-Induced Inflammatory Pain: Antinociceptive Effects Enhanced and Tolerance Development Accelerated
- 190 Downloads
We have previously shown that electroacupuncture (EA) produced antinociception through the release of endogenous opioid peptides to activate opioid receptors during acute nociception. EA produced tolerance after its prolonged application. It has reported that 100 Hz EA could reduce mechanical hyperalgesia in complete Freund’s adjuvant (CFA)-induced inflammatory nociception rats. The present study aims to investigate the antinociceptive effect of EA and the development of EA tolerance in chronic inflammatory nociception rats with CFA injection into the hind paw plantar. The results showed that the antinociceptive effect of 100 Hz EA was significantly enhanced in CFA-induced inflammatory nociception rats. Naloxone at 20 mg/kg could significantly block this antinociceptive effect. Chronic tolerance to EA was developed faster in CFA-induced inflammatory nociception rats than in normal rats. Therefore, 100 Hz EA could enhance antinociceptive effects and accelerate tolerance development in CFA-induced inflammatory nociception rats. The enhancement of EA antinociceptive effect in CFA-induced inflammatory nociception rats might involve the endogenous opioid peptides such as dynorphin.
KeywordsElectroacupuncture Antinociception Complete Freund’s adjuvant Inflammatory pain Tolerance Naloxone
This work was supported by grants from the National Natural Science Foundation of China (30560145, 30600173 and 30570566), the Scientific and Technological Program of the Department of Education of Jiang-Xi Province, the “111” Project of the Ministry of Education of China and the “973” program of the Ministry of Science and Technology of China (2007CB512501).
- 13.Liu HX (1999) Repeated 100 Hz TENS for the treatment of chronic inflammatory pain in rats: optimal parameters and possible neurochemical mechanisms. Prog Physiol Sci 30:35–37Google Scholar
- 17.Ren MF, Han JS (1979) Rat tail-flick acupuncture method. Chin Med J 92:576–582Google Scholar
- 20.Tian JH, Zhang W, Fang Y, Xu W, Grandy DK, Han JS (1998) Endogenous orphanin FQ: evidence for a role in the modulation of electroacupuncture antinociception and the development of tolerance to antinociception produced by morphine and electroacupuncture. Br J Pharmacol 124:21–26PubMedCrossRefGoogle Scholar