Body-rotation induced analgesia in male mice: effects of duration and type of rotation procedure.

The effects of body-rotation in a horizontal plane on the nociceptive responses of male mice were examined. In the first experiment the mice were rotated (70 rpm, schedule of 15 sec on; 5 sec off) for 30 minutes or exposed to sham rotation. The animals were then placed on a warm surface (47.5 degrees C) and their latency to show a foot-licking response was measured. Immediately after the preceding rotation procedure a trend toward a significant increase in response latencies, indicative of analgesia, was observed (p = 0.057). However, if tested 30 minutes after the end of the rotation period, no analgesia could be demonstrated (p greater than 0.50). In Experiment 2 mice were rotated (15 sec on; 5 sec off) or sham rotated for durations of 60 or 90 minutes. Response latencies were significantly elevated (p less than 0.01) after both rotation durations, but not differentially so (p greater than 0.20). In the last experiment the effects of 60 minutes of the intermittent rotation procedure (15 sec on; 5 sec off) were compared to those of 60 minutes of continuous rotation. Both types of rotation resulted in the induction of analgesia and the intermittent procedure produced a significantly greater degree of analgesia than the continuous rotation (p less than 0.05). These experiments demonstrate that 60 to 90 minutes of body-rotation can produce a significant "stress-induced" analgesia in mice and that an intermittent schedule of rotation is more effective than a continuous rotation exposure.(ABSTRACT TRUNCATED AT 250 WORDS)