Extrinsic sympathetic reinnervation after intestinal transplantation in rats

Although extrinsic denervation is inevitable after intestinal transplantation and leads to poor intestinal function, little is known about the occurrence of extrinsic reinnervation. In this study, extrinsic sympathetic reinnervation was investigated morphologically following syngeneic intestinal transplantation performed on male Lewis strain rats. At 1, 3, 6, 9, 15, and 27 weeks after transplantation, the graft mesenteric arteries and their branches in the intestinal wall were histochemically 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 arteries, where it traversed the arterial anastomosis and extended along the course of the mesenteric arteries from proximal to distal. The degree of reinnervation in the mesenteric arteries was similar to the results obtained in the simple denervation model. The transplanted intestinal tract itself was sympathetically denervated for at least 9 weeks after transplantation, and reinnervation was not recognized until 15 weeks after transplantation. Reinnervation extended into the intestinal wall in every preparation, and the enteric nerves began to be reinnervated at 27 weeks after transplantation, but the density was still at a low level and complete extrinsic reinnervation of the graft would seem to require a much longer time to reestablish itself.