This study investigated whether and how electroacupuncture (EA) attenuates cold hypersensitivity (allodynia) in a rat model of oxaliplatin-induced neuropathic pain. Cold allodynia [evaluated by immersing the tail into cold water (4 C) and measuring the withdrawal latency] was induced 3 days after an oxaliplatin administration (6 mg/kg, i.p.). EA stimulation (2/100 Hz, 0.3-ms pulse duration, 0.2-0.3 mA) was delivered to ST36 acupoint or non-acupoint for 20 min. Low-frequency (2 Hz) EA at ST36 relieved cold allodynia more effectively than high-frequency EA at ST36 or low-frequency EA at non-acupoint. Naloxone (opioid antagonist, 2 mg/kg, i.p.) completely blocked such EA-induced anti-allodynia, whereas phentolamine (α-adrenergic antagonist, 2 mg/kg, i.p.) did not. Moreover, plasma β-endorphin levels significantly increased right after the end of EA and subsequently decreased. These results indicate that low-frequency EA at ST36 in rats has a marked relieving effect on oxaliplatin-induced cold allodynia that is mediated by the endogenous opioid, but not noradrenergic, system. © 2013 The Physiological Society of Japan and Springer Japan.
Cold allodynia; Electroacupuncture; Endogenous opioid; Noradrenergic; Oxaliplatin
EMTREE drug terms: alpha adrenergic receptor blocking agent; beta endorphin; naloxone; narcotic antagonist; oxaliplatin; phentolamine; platinum complex
EMTREE medical terms: animal; animal behavior; article; blood; chemically induced disorder; cold; disease model; electroacupuncture; hyperalgesia; male; pain threshold; pathophysiology; rat; reaction time; Sprague Dawley rat; time
MeSH: Adrenergic alpha-Antagonists; Animals; Behavior, Animal; beta-Endorphin; Cold Temperature; Disease Models, Animal; Electroacupuncture; Hyperalgesia; Male; Naloxone; Narcotic Antagonists; Organoplatinum Compounds; Pain Threshold; Phentolamine; Rats; Rats, Sprague-Dawley; Reaction Time; Time Factors
Medline is the source for the MeSH terms of this document.
Chemicals and CAS Registry Numbers: beta endorphin, 59887-17-1; naloxone, 357-08-4, 465-65-6; oxaliplatin, 61825-94-3; phentolamine, 50-60-2, 73-05-2