Electric stimulation of the cingulum bundle precipitates onset of autotomy induced by inflammation in rat

The purpose of this work was to test if electric stimulation of the cingulum bundle in animals subjected to a hindpaw inflammatory process precipitates the onset and enhances autotomy behaviour. Wistar rats were implanted with bipolar parallel electrodes in the boundary of the cingulum bundle. The inflammatory process was induced in all subjects by injection of carrageenan. The groups were: A, sham; B, implanted and stimulated 10 min daily for 7 days; C, implanted and stimulated 2 h daily, for 7 days. Both groups were injected with CAR 2 days after ending the stimulation period; and D, implanted and stimulated 10 min daily for 5 days, the first stimulation being simultaneous to CAR injection. Results show that 100% of the subjects in stimulated groups presented autotomy as compared with 66% in the sham group. A significant shortening of the onset and increased rates in autotomy were observed in experimental groups (B, C and D) as compared to the sham group. We did not find differences between groups B and C, but there was an increment of autotomy in group D when compared with both B and C groups. We conclude that it is possible to facilitate the onset and to increase the intensity of the autotomy triggered by the inflammatory process with cingulum bundle electrical stimulation. The results also suggest that a fundamental condition to the development of the autotomy in this model is the presence of the noxious inflammatory process. Copyright 1999 European Federation of Chapters of the International Association for the Study of Pain.