Choline acetyltransferase activity in collateral sprouting of peripheral nerve after surgical intervention: Experimental study in rats

The purpose of this study was to establish an assay of choline acetyltransferase (ChAT) activity to investigate the regeneration of injured peripheral nerve, repaired by end-to-end or end-to-side neurorrhaphy. Murine sciatic and peroneal nerves were exposed, and the peroneal nerve was transected at a site 5 mm from its ramification. For end-to-side neurorrhaphy, an epineurotomy producing a 5- x 5-mm window was carried out on the tibial nerve, just above the level of gastrocnemius muscle ramification. The peroneal nerve stump was then sutured end-to-side to the tibial nerve window. For end-to-end neurorrhaphy, the peroneal stump was directly sutured end-to-end. ChAT activity was measured at a site distal to the peroneal stump at 1 to 3 months postoperatively, and the results were compared among four groups: 1) end-to-end neurorrhaphy group; 2) end-to-side neurorrhaphy group; 3) unrepaired group; and 4) positive controls. ChAT activity in the end-to-side neurorrhaphy yielded approximately two-thirds the value of the end-to-end neurorrhaphy, and more than half the value of positive controls at 3 months postoperatively. Histologic sections of the end-to-side and end-to-end sutured peroneal nerve demonstrated large numbers of myelinated axons and Schwann cells at the third postoperative month. All the results demonstrated that end-to-side neurorrhaphy is comparable to well-performed end-to-end neurorrhaphy, thus providing another option for surgical treatment of avulsion nerve injury and massive nerve defect.