Expression of peptide transporter following intestinal transplantation in the rat

Background. The absorptive function of the intestinal graft is one of the m ost important factors for successful intestinal transplantation. To clarify whether the intestinal H+/peptide cotransporter (PEPT1) was expressed in t he transplanted intestine, we examined the expression of PEPT1 in an experi mental model of rat small intestinal transplantation in comparison with exp ression of Na+/glucose cotransporter (SGLT1). Materials and methods. Heterotopic intestinal transplantation was performed in allogeneic and syngeneic rat strain combinations. An additional group o f allogeneic recipients was treated with tacrolimus (1 mg/kg) prior to tran splantation, then daily for 7 days. Intestinal grafts were examined for his topathology and PEPT1 and SGLT1 expression. Results. In the isografts, the levels of messenger RNA (mRNA) encoding both transporters were not changed, while the amount of SGLT1 protein was decre ased and that of PEPT1 protein was increased. In the allografts, mRNA level and protein amount of both transporters and the amount of villin protein w ere decreased, and microscopic examination revealed histopathological featu res of rejection on day 7. Tacrolimus treatment ameliorated the histopathol ogical features and prevented the decrease in villin protein expression. Ho wever, the decreases in PEPT1 and SGLT1 expression (both mRNA and protein) were partially prevented by tacrolimus treatment. Conclusions. This study indicated that the expression of transporters shoul d be determined to evaluate intestinal graft function in addition to histop athological examination of the mucosa and that the levels of mRNA encoding intestinal nutrient transporters in biopsy specimens may be useful for eval uating the intestinal graft function for intestinal transplant patients. (C ) 2001 Academic Press.