EFFECTS OF CEREBRAL CORTICAL AND STRIATAL LESIONS ON AUTOTOMY FOLLOWING PERIPHERAL NEURECTOMY IN RATS

Peripheral nerve lesions have been reported to produce deafferentation pain and persistent changes at various levels of the central nervous system. Using autotomy in rats following leg denervation, as a model f or deafferentation pain, we studied the effect of various cerebral les ions on this abnormal behavior. Under deep anesthesia, rats were subje cted either to massive hemidecortication or to subtotal hemispherectom y (involving parts of basal ganglia and limbic areas), which was follo wed 1 week later by a denervation of the ipsilateral or contralateral leg. Hemidecortication significantly delayed autotomy from 7.8 +/- 2.8 to 25.6 +/- 2.1 days without reducing its incidence, whereas hemisphe rectomy abolished the incidence of autotomy in the contralaterally den ervated leg and delayed its onset from 7.8 +/- 2.8 to 34 +/- 6.1 days and decreased its incidence (from 100% to 60%) in the ipsilaterally de nervated leg. Chemical lesions of the neostriatum produced similar eff ects on autotomy to those produced by hemispherectomy. Hemispherectomi zed and striatum-lesioned rats that failed to elicit autotomy in the c ontralaterally denervated leg were subjected after 7 weeks to denervat ion of the ipsilateral leg. Sixty to seventy percent of these rats sho wed autotomy and in half of them the attack was directed simultaneousl y to both legs. These results suggest an involvement of the cerebral c ortex and a stronger contribution of subcortical structures (like stri atum and limbic system) in the processing of nociceptive information.