Inhibitory effect of intrathecal meptazinol on carrageenan-induced thermal hyperalgesia in rats.
The effect of meptazinol in the spinal cord on carrageenan-induced hyperalgesia was investigated. The latency of paw withdrawal (PWL) to a thermal stimulus was used as an index of inflammatory hyperalgesia in awake rats. Intrathecal (i.t.) injection of 10 and 100 microg meptazinol markedly increased the PWL of the carrageenan-injected paw (P<0.01). The PWL of the non-injected paw was not detectably affected by the administration of meptazinol at the doses tested. I.t. injection of naloxone (5 microg) or atropine (1 microg) alone exhibited no effect on the PWLs of either the carrageenan-injected or non-injected paw. Pretreatment with naloxone, but not atropine, completely blocked the meptazinol-induced anti-hyperalgesia. These observations suggested that mu opioid receptor rather than muscarinic acetylcholine receptor may be involved in the anti-hyperalgesia of meptazinol in the spinal cord.
Zhang
Hua
H
Institute of Neurobiology, Fudan University, Shanghai, 200433, China.
Zhang
Yu-Qiu
YQ
Qiu
Zhui-Bai
ZB
Zhao
Zhi-Qi
ZQ
D000818:Animals; D002351:Carrageenan / Q000037:antagonists & inhibitors / Q000633:toxicity*; D004305:Dose-Response Relationship, Drug; D006930:Hyperalgesia / Q000139:chemically induced* / Q000188:drug therapy*; D007278:Injections, Spinal; D008159:Lumbar Vertebrae / Q000187:drug effects / Q000502:physiology; D008297:Male; D008621:Meptazinol / Q000008:administration & dosage*; D010147:Pain Measurement / Q000187:drug effects / Q000379:methods; D051381:Rats; D017207:Rats, Sprague-Dawley; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology
D008621:Meptazinol; D002351:Carrageenan