NEONATAL GUANETHIDINE SYMPATHECTOMY SUPPRESSES AUTOTOMY AND PREVENTS CHANGES IN SPINAL AND SUPRASPINAL MONOAMINE LEVELS INDUCED BY PERIPHERAL DEAFFERENTATION IN RATS

In the rat, sciatic and saphenous nerve section resulted in self-mutil ation of the ipsilateral limb. Fifteen and 60 days after surgery, mono amine levels were altered not only in the spinal cord but also in supr aspinal structures. Thus, in the ipsi- and contralateral sides of the spinal lumbar region, an increase in the levels of 5-hydroxyindoleacet ic acid (5-HIAA) was observed 15 days after surgery and in the levels of serotonin (5-HT) and noradrenaline 60 days later. Changes in the co ntent of 5-HT and its metabolite were also evident, at these time poin ts, in periaqueductal gray matter and trigeminal nucleus. Chemical sym pathectomy carried out by administering guanethidine to neonatal rats reduced the degree of autotomy and suppressed the changes in monoamine rgic systems following peripheral neurectomy. This study supports the hypothesis that the local noradrenaline outflow from sympathetic fiber s in the neuroma is one of the causal factors in autotomy and it indic ates that autotomy is under the control of descending monoaminergic pa thways originating in brain-stem nuclei.