Changes in rat intestinal motility and absorption following intestinal transplantation: an experimental study

Intestinal transplantation (ITx) is a life-saving procedure for patients with complicated intestinal failure. In the acute phase, allograft permeability increases primarily due to ischemia-reperfusion injury. However, long-term allograft physiology after transplantation remains poorly understood, particularly the impact of lost autonomous graft innervation. This study aims to evaluate post-ITx allograft motility and permeability using orally administered fluorescein-labeled dextrans (TRITC70,FITC4). Lewis-to-Lewis orthotopic ITx (n = 6, 260-300 g) were performed. Intestinal permability and motility were evaluated in recipient at baseline (2 days pre-transplant, control) and 4 weeks post-transplant (experimental), using orally administered dextrans (TRITC70 and FITC4). Total GI motility was assessed by TRITC70 fecal excretion, while intestinal and colonic permeability were evaluated using TRITC70 (transcellular route) and FITC4 (paracellular route) plasma concentrations, measured at 3 h, 6 h, 24 h. Paired data were reported as mean (±SEM) and compared using paired t-test (normal distribution)/Wilcoxon rank test (non-normal distribution). Fecal excretion of TRITC70 was 9.58 (±0.85) hours in the control group and 11.02 (±1.40) hours in the experimental group (p = 0.287). Plasma concentrations (µg/mL) of FITC4 at 3 h, 6h, and 24 h were (control vs. experimental): 0.23 (±0.08) vs. 0.72 (±0.23) (p = 0.041), 0.12 (±0.06) vs. 0.53 (±0.16) (p = 0.031), and 0.04 (±0.02) vs. 0.12 (±0.04) (p = 0.625). For TRITC70, plasma concentrations were 11.20 (±1.81) vs. 11.11 (±1.39) (p = 0.975), 20.49 (±8.87) vs. 12.60 (±1.87) (p = 0.562), and 20.82 (±7.25) vs. 5.02 (±0.82) (p = 0.094). Finally, the AUC (µgh/mL) of FITC4 and TRITC70 absorption were 2.39 (±1.1) vs. 8.84 (±2.69) (p = 0.029) and 436 (±159) vs. 197 (±25) (p = 0.195), respectively. Four weeks after ITx, we observed an increased paracellular permeability compared to pre-transplant evaluation, while overall GI motility remained unchanged. Further research is needed to better understand intestinal graft physiology.