title: Acupuncture alleviates the affective dimension of pain in a rat model of inflammatory hyperalgesia.
abstract: Although studies demonstrate that electroacupuncture (EA) alleviates the sensory dimension of pain, they have not addressed EA's effect on the affective dimension. An inflammatory pain rat model, produced by a complete Freund adjuvant (CFA) injection into the hind paw, was combined with a conditioned place avoidance test to determine EA's effects and its underpinning mechanism on the affective dimension of pain. CFA-injected rats showed place aversion, i.e. the affective dimension of pain, by spending less time in a pain-paired compartment after conditioning than before, while saline-injected rats did not. CFA rats given EA treatment at GB30 before a post-conditioning test showed no aversion to the pain-paired compartment, indicating that EA inhibited the affective response. Intra-rostral anterior cingulate cortex (rACC) administration of a κ-, but not μ-opioid receptor antagonist, blocked EA action. These data demonstrate that EA activates opioid receptors in the rACC to inhibit the affective dimension of pain.
authors.affiliation: Center for Integrative Medicine, School of Medicine, University of Maryland, 685 W. Baltimore Street, MSTF Rm 8-22, Baltimore, MD 21201, USA.
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhang
authors.forename: Xianze
authors.initials: X
authors.lastname: Meng
authors.forename: Aihui
authors.initials: A
authors.lastname: Li
authors.forename: Jiajia
authors.initials: J
authors.lastname: Xin
authors.forename: Brian M
authors.initials: BM
authors.lastname: Berman
authors.forename: Lixing
authors.initials: L
authors.lastname: Lao
authors.forename: Ming
authors.initials: M
authors.lastname: Tan
authors.forename: Ke
authors.initials: K
authors.lastname: Ren
authors.forename: Rui-Xin
authors.initials: RX
authors.lastname: Zhang
mesh_terms: D000339:Affect / Q000502:physiology*; D000818:Animals; D001362:Avoidance Learning; D003214:Conditioning, Classical; D004195:Disease Models, Animal; D015671:Electroacupuncture; D005620:Freund's Adjuvant; D006179:Gyrus Cinguli / Q000502:physiology; D006930:Hyperalgesia / Q000628:therapy*; D007249:Inflammation / Q000628:therapy; D008297:Male; D009271:Naltrexone / Q000031:analogs & derivatives / Q000494:pharmacology; D059408:Pain Management / Q000379:methods*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017473:Receptors, Opioid, kappa / Q000037:antagonists & inhibitors; D017450:Receptors, Opioid, mu / Q000037:antagonists & inhibitors; D013004:Somatostatin / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: D017473:Receptors, Opioid, kappa; D017450:Receptors, Opioid, mu; C049352:phenylalanyl-cyclo(cysteinyltyrosyl-tryptophyl-ornithyl-threonyl-penicillamine)threoninamide; C051844:norbinaltorphimine; D013004:Somatostatin; D009271:Naltrexone; D005620:Freund's Adjuvant