Acetylcholine synthesizing activity and nicotinic binding sites in rat hind limb muscles during reinnervation

Abstract

Acetylcholine synthesizing (ACh-s) activity and binding of the nicotinic ligands ³H-α-bungarotoxin (α-Btx) and ³H-d-tubocurarine (d-TC) were analysed in rat hind limb muscles for up to 6 months after a cryolesion of the sciatic nerve. Muscles of the contralateral leg served as controls. After cryolesion there was a rapid decrease in ACh-s activity parallel to a considerable increase in α-Btx binding. A clearcut increase in ACh-s activity was first seen at 32 days and complete restoration in ACh-s activity was seen from 2–3 months postoperatively. From the 16th day there was a rapid decrease in α-Btx binding sites and initial values were seen at the 32nd day postoperatively. D-TC binding sites were relatively unchanged during the experimental period. The first neurophysiological signs of reinnervation were seen at 16 days. The rats were observed to move normally about 2 months postoperatively. Normalization of α-Btx binding sites seems to be an earlier sign of reinnervation than normalization of ACh-s activity.