ラット坐骨神経に対する高周波熱凝固の効果

Abstract

We applied radiofrequency thermocoagulation(R.F.T.C) to the rat. sciatic nerve on one side of the body. Animals were divided into four groups, to which R.F.T.C was applied at temperatures of 50, 60, 70 and 80℃, respectively, for 45 seconds. Autotomy, motor function, and response to heat and mechanical stimulation were examined for 6 weeks. Autotomy was observed in the foot on the R.F.T.C side, in proportion to the increase in the R.F.T.C temperature above 60℃. Normal responses of digit spread, grip strength and foot drop in motor function were reduced immediately after R.F.T.C treatment, and then recovered slowly at a rate dependent on the temperature. A nociceptive test based on heat stimulation of the plantar showed temporary hyperalgesia on the R.F.T.C side. A touch sensitivity test for mechanical stimulation using Von Frey hair filaments was more sensitive on the R.F.T.C side. with increased temperature. It was concluded that these rats had similar characteristics to a neuropathic pain model. In a second study, we adrninistered sarpogrelate hydrochloride orally to rats with R.F.T.C applied to the sciatic nerve at 70℃ for 45 seconds. Each rat was then examined for 8 weeks. In the sarpogrelate hydrochloride group, the R.F.T.C effects decreased in both number and extent of autotomy, and the abnormal motor function response, and especially the grip strength, recovered a little more quickly. Hyperesthesia observed upon heat and mechanical stimulation also declined more rapidly, and the number of animals with this condition decreased. Histologically, we have observed axon degeneration in the sciatic nerve on the R.F.T.C side, and reduced degeneration was observed following sarpogrelate hydrochloride treatment. Sarpogrelate hydrochloride is a selective serotonin (5HT2) receptor antagonist that results in anticoagulation of thrombocytes and expansion of blood vessels. Hence, it may have positive effects on the microcirculation following R.F.T.C-induced nerve injury.