NERVE-TERMINALS CONTAINING NEUROPEPTIDES DECREASE IN NUMBER AFTER MASSIVE PROXIMAL SMALL-BOWEL RESECTION IN THE PIGLET

The aim of this study was to evaluate possible changes in the neuropep tide innervation pattern of the remaining porcine ileum following 75% proximal resection of the small intestine. Three-month-old piglets wer e operated on and two months postoperatively full-thickness specimens of the proximal part of the distal ileum wall were taken. Age-matched 3- and fi-month-old unoperated piglets were used as controls. The numb er and intensity of VIP-, galanin-, enkephalin-, substance P-, and som atostatin-containing nerve fibers were estimated in sections processed for immunofluorescence microscopy and subjected to quantitative scori ng. The VIP-, galanin-, and enkephalin-immunoreactive fibers of the ci rcular muscle layer and villi were also quantitated by computer-assist ed morphometry. The number and intensity of VIP-immunoreactive fibers in the mucosa and circular muscle layer markedly decreased after resec tion as compared to 3-month-old and 5-month-old controls (P < 0.05). T he galanin immunoreactivity index decreased significantly after resect ion in the circular muscle layer as compared to both control groups (P < 0.05). The increase in the number of enkephalin-immunoreactive nerv e fibers that normally occurred from 3 to 5 months of age was inhibite d by the resection. We were not able to see any differences in somatos tatin or substance P immunoreactivity between the groups. The results suggest that massive resection induces significant changes in the neur opeptide-containing innervation of the remaining small intestine. Thes e findings are compatible with altered motor activity and mucosa funct ion in the remain intestine.