Inhibitory Mechanism of Periaqueductal Gray Matter on Neuropathic Pain in Rat. |
Kim, Bong Ok , Ryu, Jae Wook , Seo, Jeong Su , Sohn, Jin Hoon |
1Department of Rehabilitation, College of Medicine, Chungnam National University. 2Department of Psychology, College of Social Science, Chungnam National University. |
흰쥐 중뇌수도주변 회백질의 신경병리성 통증 억제 기전 |
김봉옥, 유재욱, 서정수, 손진훈1 |
충남대학교 의과대학 재활의학교실, 1사회과학대학 심리학과 |
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Abstract |
Objective Using Lee et al (1996) model, we assessed the effect of opioid within the PAG on the manifestations of the neuropathic pain, and we studied the effects of naloxone on the analgesic effects of opioid. Method Under pentobarbital anesthesia, male Sprague-Dawley rats were implanted with cannula in the ventral (n=10) and dorsal (n=6) PAG after the unilateral tibial and sural nerves were ligated and cut, leaving the common peroneal nerve intact. Pain sensitivity was assessed using the von Frey filament (8 mN) and acetone applied to the sensitive area for 1 week postoperatively. Rats with neuropathic pain were intracerebrally microinjected with DAMGO (0.1μg/5μl) and enkephaline (20μg/5μl) into the ventral and dorsal PAG and the pain sensitivity was assessed. Naloxone was injected to assess the observed change of pain sensitivity. Results Intracerebral microinjection of DAMGO and enkephaline into the ventral PAG, but not the dorsal PAG, increased the pain threshold which was reversed by naloxone. Conclusion The results suggest that stimulation of the ventral PAG in neuropathic rats may reduce neuropathic pain via opioid-mediating pathway of the descending pain inhibition system.
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Key Words:
Periaqueductal gray matter (PAG), Neurophatic pain,Opioid |
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