Immunohistochemical demonstration of enteric nervous distribution after syngeneic small bowel transplantation in rats

Background. Small bowel transplantation causes a disturbance of the enteric neural networks after complete extrinsic denervation. Methods. The morphologic changes in the enteric nervous system after transplantation were immunohistochemically investigated in jejunal isografts at 10 days, 100 days, and 400 days after transplantation. Results. No remarkable differences were revealed concerning the antibodies for general neural markers, vasoactive intestinal polypeptide, substance P, somatostatin, or galanin between controls and isografts. Identical differences were detected in the distribution of nerve fibers containing calcitonin gene-related peptide and catecholamines. In the isografts a partial reduction of calcitonin gene-related peptide-immunopositive fibers was shown. A complete elimination of catecholaminergic nerves was seen in the isografts at 10 and 100 days; however, a sparse distribution of catecholaminergic nerves was observed in the 400-day isograft. Conclusions. Most intrinsic neural elements are preserved; however, the extrinsic, sympathetic, and sensory nerves are completely disrupted as a consequence of transplantation. Reinnervation of extrinsic nerve fibers could occur in the transplanted small intestine.