|
KMID : 0811720030070000175
|
|
Korean Journal of Physiology & Pharmacology
2003 Volume.7 No. 0 p.175 ~ p.0
|
|
|
Reduction of Nerve Injury-Induced Spinal μ-Opioid Receptors is Related to the Generation of Mechanical Allodynia in Rats
|
|
Back Seung-Keun
Lee Jae-Hee
Hong Seung-Kil
Na Heung-Sik
|
|
|
Abstract
|
|
|
|
Partial peripheral nerve injury is followed by the reduction of spinal μ-opioid receptors and by the generation of neuropathic pain. In the present study, we examined whether 1) the decrease in spinal μ-opioid receptors following peripheral nerve injury was related to the generation of neuropathic pain and 2) naloxone, μ-opioid receptor antagonist, could aggravate the signs of neuropathic pain. To these aims, we compared the amount of spinal μ-opioid receptors between the two groups of rats that showed the extremely different severity of mechanical allodynia 2 weeks following the unilateral transection of the inferior and superior caudal trunks between the S1 and S2 spinal nerves; one group (allodynic group) exhibited the robust mechanical allodynia sign after the nerve injury, whereas the other group (non-allodynic group) did not show the sign despite the same nerve injury. Immunohistochemical and western blot analyses demonstrated that spinal μ-opioid receptor immunoreactivity more decreased in allodynic group than in non-allodynia group. And, naloxone (1 and 2 mg/kg, i.p.) treatment dramatically aggravated the signs of mechanical allodynia in the non-allodynic group. These results suggest that the generation of mechanical allodynia depends upon the extent of decrease in spinal μ-opioid receptors following peripheral nerve injury.
|
|
|
KEYWORD
|
|
|
Peripheral nerve injury, Mechanical allodynia, Spinal μ-opioid receptor, Naloxone, Neuropathic pain
|
|
|
FullTexts / Linksout information
|
|
|
|
|
Listed journal information
|
|
  
|