Autotomy after nerve sections in the rat is influenced by tonic descending inhibition from locus coeruleus

This study examined the role of descending brainstem inhibition on autotomy (self-mutilation) produced by neurectomy, and on the enhancement of autotomy by an injury prior to denervation. Autotomy after sciatic and saphenous nerve sections was examined following lesions of the locus coeruleus (or sham lesions) in rats which were either uninjured or previously injured by an injection of formalin into the hindpaw. The prior injury of the paw produced a significant increase in autotomy which occurred earlier in rats with lesions of the locus coeruleus than in the sham controls. The locus coeruleus lesion by itself also produced an enhancement of autotomy. These results suggest that self-mutilation following neurectomy, and possibly its enhancement by prior injury, are subject to tonic inhibition due to descending controls from the locus coeruleus.