Roles of nitric oxide synthase in acute rejection of intestinal transplantation in rats

Objective To evaluate the role of neuronal (nNOS) and inducible nitric oxide synthase (iNOS) in acute rejection (AR) of intestinal transplantation in rats.Methods The rat orthotopic intestinal transplantation was performed.Animals were assigned to following 2 groups:isograft group ( A,Lewis→Lewis,n =12) ; allograft group (B,DA→Lewis,n =12).The survival time was observed.At 30 min,postoperative day (POD) 1,3,5 and 7,the serum nitric oxide (NO) levels were measured,the maltose absorption tests were performed,and intestinal specimens were resected for light microscopy after H&E staining.The activity of nNOS and iNOS was examined by immunohistochemistry.The expression levels of nNOS and iNOS mRNA were detected by using reverse transcription-polymerase chain reaction (RT-PCR).Results The survival time in groups A and B was ＞ 30 and (6.83 ±0.75 ) days respectively.In group A,the staining and mRNA expression of nNOS were weakened obviously after reperfusion and returned to normal degree on POD 3 and 7 respectively.The staining and mRNA expression of iNOS were increased after reperfusion and then decreased gradually.As compared with group A,from POD 3 to 7,the nNOS staining was weakened,the iNOS staining was strengthened,the serum NO levels were increased significantly (P ＜ 0.05 ),and the blood glucose absorption levels reduced significantly (P ＜ 0.01 ) in group B.On POD 5 and 7,the nNOS mRNA expression levels were decreased significantly (P ＜ 0.01 ) and the iNOS mRNA expression levels increased significantly (P ＜ 0.001 ) in group B.Conclusion During the AR period,nNOS regulates the expression of iNOS probably.The activity and expression of nNOS have close relations with the graft structure and absorptive function.The activity of iNOS is one of important factors in exacerbating tissue damage. Key words: Intestinal transplantation;  Nitric oxide synthase;  Acute rejection