Effect of mexiletine on thermal allodynia and hyperalgesia in diabetic mice

The antinociceptive effect of mexiletine in diabetic mice was examined. Tai l-flick latencies at heat intensity of 35 and 50 V in diabetic mice were sh orter than those in non-diabetic mice. In diabetic mice, mexiletine increas ed the tail-flick latency at 35 V to the level observed in non-diabetic mic e. The tail-flick latency at 50 V in diabetic mice, but not in non-diabetic mice, was increased by pretreatment with capsaicin (0.56 nmol, i.t., 24 h) . The antinociceptive effect of mexiletine in diabetic mice was reduced by capsaicin. These results suggest that the mexiletine-induced antinociceptio n in diabetic mice involves the inhibition of the nociceptive transmission of capsaicin-sensitive primary afferent fibers.