EXTRINSIC SYMPATHETIC REINNERVATION AFTER INTESTINAL TRANSPLANTATION IN RATS

Although extrinsic denervation is inevitable after intestinal transpla ntation and leads to poor intestinal function, little is known about t he occurrence of extrinsic reinnervation. In this study, extrinsic sym pathetic reinnervation was investigated morphologically following syng eneic intestinal transplantation performed on male Lewis strain rats. At 1, 3, 6, 9, 15, and 27 weeks after transplantation, the graft mesen teric arteries and their branches in the intestinal wall were histoche mically examined by a glyoxylic acid method demonstrating perivascular sympathetic nerve fibers. At 3 weeks after transplantation, extrinsic sympathetic reinnervation was recognized in the graft mesenteric arte ries, where it traversed the arterial anastomosis and extended along t he course of the mesenteric arteries from proximal to distal. The degr ee of reinnervation in the mesenteric arteries was similar to the resu lts obtained in the simple denervation model. The transplanted intesti nal tract itself was sympathetically denervated for at least 9 weeks a fter transplantation, and reinnervation was not recognized until 15 we eks after transplantation. Reinnervation extended into the intestinal wall in every preparation, and the enteric nerves began to be reinnerv ated at 27 weeks after transplantation, but the density was still at a low level and complete extrinsic reinnervation of the graft would see m to require a much longer time to reestablish itself.