Changes of wide dynamic range neuronal responses to mechanical cutaneous stimuli following acute compression of the rat sciatic nerve.

To investigate the changes in central neuronal activity in response to cutaneous stimulation following acute nerve compression, the responses of wide dynamic range dorsal horn neurons (n = 13) to graded mechanical cutaneous stimuli (brush, press, pinch, and squeeze) were recorded in anesthetized male Sprague-Dawley rats before and during compression, and after the release of the compression. A small vascular clip (pinching force, 120 g) was applied to compress the sciatic nerve for 30 min. In 12 neurons, background activities increased transiently for 1.5 to 4 min after nerve compression. Similarly, after the release of the compression, 7 neurons showed a transient increase in background activities. The responses to brush, press, and pinch were inhibited significantly 10 min after the nerve compression. The responses to press and pinch recovered gradually after the release of the compression. Responses to squeeze were little affected throughout the experimental period. Acute compression of the rat sciatic nerve can cause short periods of continuous increased spontaneous firing and can attenuate the dorsal horn neuronal responses to cutaneous stimuli. In particular, the neuronal responses to innocuous stimuli were more susceptible to compression of the nerve than the responses to noxious stimuli.