EXTRINSIC INTESTINAL REINNERVATION AFTER CANINE SMALL-BOWEL AUTOTRANSPLANTATION

Background. The process of extrinsic reinnervation after small bowel t ransplantation is poorly understood. Methods. Jejunal and ileal specim ens, obtained from the dogs that underwent intestinal autotransplantat ion by an end-to-end (E-E) or end-to-side arterial reconstruction, wer e analyzed at 1 (n = 7), 3 (n = 6), 6 (n = 6), 12 (n = 6), or 24 (n = 2) months and compared with control specimens (n = 7). Tissue catechol amine levels and indirect immunohistochemistry results for extrinsic n europeptides, calcitonin gene-related peptide, neuropeptide Y, substan ce P, and tyrosine hydroxylase (TH) were examined. Results. Catecholam ine levels in the grafts were undetectable until 6 months but increase d significantly after 12 months, particularly in the E-E group. Immuno histochemistry results showed no significant indication of extrinsic r einnervation until 12 months, when TH fibers were observed in five of six dogs. The E-E group revealed some TH fibers extending across the a rterial anastomosis toward the graft mesentery. Examination of the int estinal anastomosis at 12 months showed abundant peptidergic and TH ex trinsic fibers in the host side, whereas there were few or none on the graft side. Conclusions. These results suggest that extrinsic reinner vation of the graft intestinal wall does occur but requires a prolonge d period and the major route of extrinsic reinnervation is along the a rterial axis of the intestinal graft, not beyond the enteric anastomos is.