Antinociceptive effect of mexiletine in diabetic mice.

We examined the effect of mexiletine on the threshold for pain perception as determined by the application of mechanical noxious stimuli (tail-pinch) in diabetic mice. Mexiletine produced a pronounced analgesic effect in diabetic mice in a dose-dependent manner. Mexiletine (10(-5)M) significantly inhibited the K(+)-evoked release of substance P from the slices of spinal cord of diabetic mice. These results suggest that the reduction of release of substance P from the nociceptive afferent terminal in the spinal cord is involved in the mechanisms of mexiletine analgesia in diabetic mice.