Indoleamine2, 3-dioxygenase enzyme activity detected by in vivo liver microdialysis after rat ortho topic liver transplantation

Abstract

Objective To observe the activity of indoleamine 2, 3-dioxygenase (IDO) enzyme in vivo after rat liver transplantation, and the effects of liver transplantation rejection on IDO enzyme activity.Methods Ten SD rats were subjected to othotopic liver transplantations respectively in allogenic OLT group (SD→SD) and heterogenic OLT group (Wistar→SD). In the other 10 SD rats, the blood supply to the liver was obstructed for 15 min for simulating the anhepatic period in the OLT group ( sham group). An in vivo rat liver microdialysis-HPLC system was established on the day I after OLT. The concentrations of kynurenine and tryptophan in dialysate samples were continuously monitored quantitatively and reproducibly for more than 2 weeks in the same animal. Results The average concentrations of tryptophan in dialysate were 97. 14, 85.71, 53.07 nmol/L respectively in the sham, allogenic OLT and heterogenic OLT groups respectively. The concentrations of kynurenine were 3.46, 14. 58, 46.79 nmoL/L in the sham, allogenic OLT and heterogenic OLT groups respectively. The concentration of kynurenine was increased significantly on the day 7 after surgery in heterogeneic OLT group (70. 75 nmol/L). Conclusion The transplantation surgery can induce the activity of IDO enzyme in vivo and accelerate the metabolism of tryptophan in the liver allografts. Key words: Liver transplantation; Acute rejection; Immune tolerance; Tryptophane; Indoleamine 2,3-dioxygenase