抄録
We attempted to produce an animal model of trigeminal neuralgia by chronic nerve constriction injury (CCI) and investigated the time course of pain thresholds in the chronic state. Adult male Wistar rats (250 to 300 g) were used in these experiments. All rats were anesthetized with pentobarbital before surgery. Two ligatures 2 mm apart were made loosely around the unilateral supraorbital nerve with 4-0 silk (n=21) . Control animals underwent a sham operation (n= 6) . In the ligation group, carbamazepine was administered intraperitoneally to 15 rats every day for 10 days from the 10th postoperative day. The sham group (n=6) and the ligation group (n=6) to which carbamazepine was not administered were observed for 40 days after the surgery. Heat and pressure stimulation tests wer performed on these animals. The carbamazepine group (n=15) was observed for 20 days and heat stimulation was performed on this group. Both the avoidance latency to heat stimulation and the avoidance threshold to pressure stimulation were significantly lower on the CCI operation side than on the intact side. The short latency and low threshold lasted for 40 days. In the carbamazepine group the latency of the avoidance response to heat stimulation on the intact side was dose-dependently prolonged. However, on the CCI side 5 mg/kg carbamazepine had the same effect as 10 mg/kg. We believe this to be the first study of neuralgia in the region of the supraorbital nerve and of the estimation of the therapeutic effect of carbamazepine against chronic neuropathic pain. The model is easy to produce and might be useful for investigating the pathophysiology, etiology, and treatment of trigeminal pain.
