Protective Effects Of Low-dose FK506 Preconditioning On Ischemia/Reperfusion Injury In Rat With Small Bowel Transplantation

Objectives1. To establish the model of ischemia/reperfusion injury in rat with small bowel transplantation.2. To study the effects of low-dose FK506 preconditioning on the activities of SOD,MDA, LDH in transplanted intestinal mucosa.3. To study the effects of low-dose FK506 preconditioning on the cell apoptosis during the ischemia/reperfusion injury in rat with small bowel transplantation..4. Try to find out the molecul mechanism of the protective effects. MethodsThe model of ischemia/reperfusion injury was established in inbred rat SD with small bowel transplantation. 90 rats were randomly divided into three groups:(l) the sham group , 18 (2) I/R group , 2X 18 (3) FK506 group ,2X18. Every group was further subdivided into three groups : 0.5h , 6h , 24h after reperfusion. Under slightly anesthetized , rats were pretreated with FK506 (0.3 mg/kg, i.v.) through the tail vein and then small bowel transplantation was performed 6 hr after recovery in natural condition. The cold ischemia time 2.5h and warm ischemia time 10 min were controlled. At the different time points following transplantation, the intestinal pathological changes were observed andSOD, MDA,LDH activities in intestinal mucosa were determined. The apoptotic cells were detected using immune-fluorescence cytochemistry technology. Immunohistochemistry method was used to assay the expression the HSP70.Results1. FK506 preconditioning significantly reduced the intestinal pathological changes compared with I/R group.2. Activities of SOD,MDA,LDH in intestinal mucosa were changed during the I/R injury. SOD activities in FK506 group were significantly higher than those in I/R group 6 h and 24 h after reperfusion (P<0.01) ; MDA contents were lower in FK506 group than those in I/R group 6h after reperfusion (P<0.01) ; LDH activities in FK506 group were significantly lower than I/R group at all time points (P<0.01) .3. Ischemia/reperfusion injury resulted in the increase of apoptotic cells in intestinal mucosa. Low-dose FK506 preconditioning significantly decreased the apoptotic cells. At all time points the fluorescence intensity was significantly lower in FK506 group than that in I/R group (P<0.05, PO.01).4. The faint expression of hsp70 can be seen at 24h after reperfusion in I/R group. In FK506 group, the expression of HSP70 appeared at 0.5h after reperfusion, increased at 6h, and achieved the peak expression at 24h.Conclusions1. Low-dose FK506 preconditioning significantly reduced the intestinal pathological changes associated with I/R injury in rat.2. Low-dose FK506 preconditioning significantly reduced changes of SOD, MDA, LDH activities in intestinal mucosa associated with I/R injury.3. Ischemia/reperfusion injury can induce the intestinal mucosa cellsapotosis. Low-dose FK506 preconditioning significantly decreased the apoptotic cell.4.Low-dose FK506 preconditioning has protective effect on ischemia/reperfusion injury in rat with small bowel transplantation. This protective effect may be related to the induction of hsp70.