Choline Acetyltransferase Activity in Collateral Sprouting of Peripheral Nerve after Surgical Intervention: Experimental Study in Rats

ABSTRACT

The purpose of this study was to establish an assay of choline acetyItransferase (ChAT) activity to investigate the regeneration of injured peripheral nerve, repaired by end-to-end or end-to-side neurorrha-phy. 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- × 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.