Effects of morphine on mechanical allodynia in a rat model of central neuropathic pain.
We examined whether morphine reduced the behavioral signs of neuropathic pain below level induced by T13 spinal hemisection in rats. In order to examine the effect of morphine on the mechanical allodynia, morphine alone, morphine with naloxone and saline were administered intraperitoneally and intrathecally and behavioral tests were conducted. In systemic injection, mechanical allodynia was reduced only when a higher concentration of morphine (5 mg/kg) was used. Intrathecally injected morphine (0.5, 1, 2, 5 microg) reduced mechanical allodynia dose-dependently. It is suggested that systemic morphine has limited effect on mechanical allodynia but direct spinal administration of morphine is more effective in controlling central pain following spinal cord injury.
Kim
Junesun
J
Neuroscience Research Institute and Department of Physiology, Korea University College of Medicine, Sungbuk-gu, Seoul.
Jung
Ji-In
JI
Na
Heung Sik
HS
Hong
Seung Kil
SK
Yoon
Young Wook
YW
D000818:Animals; D004195:Disease Models, Animal; D007278:Injections, Spinal; D008297:Male; D009020:Morphine / Q000494:pharmacology / Q000627:therapeutic use*; D010146:Pain / Q000188:drug therapy* / Q000503:physiopathology; D017288:Pain Threshold / Q000187:drug effects / Q000502:physiology; D010812:Physical Stimulation / Q000379:methods; D051381:Rats; D017207:Rats, Sprague-Dawley; D013119:Spinal Cord Injuries / Q000188:drug therapy / Q000503:physiopathology
D009020:Morphine