一氧化氮合成酶在大鼠小肠移植急性排斥反应中的作用

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

目的观察神经型（nNOS）和诱导型一氧化氮合成酶（iNOS）在大鼠小肠移植急性排斥反应（AR）中作用。方法行大鼠原位小肠移植。实验分为2组。1组：同系移植组（Lewis→Lewis，12例）；2组：同种移植组（DA→Lewis，12例）。观察术后生存时间。再灌注30min、术后1、3、5、7d检测血清一氧化氮（NO）浓度；开腹行麦芽糖吸收实验；切取移植肠管，苏木素-伊红（HE）染色后光镜检查。免疫组织化学法观察移植肠nNOS和iNOS的活性。逆转录-聚合酶链反应（RT—PCR）法检测移植肠nNOSmRNA和iNOSmRNA的表达。结果A组生存时间〉30d。B组生存时间为（6．83±0．75）d。再灌注后A组nNOS染色与mRNA表达明显减弱，此后nNOS染色和mRNA表达分别于术后3、7d恢复正常。再灌注后A组iNOS染色与mRNA表达增强，此后逐渐减弱。与A组比较，术后3～7d．B组nNOS染色减弱，iNOS染色增强，血清NO水平明显升高（P〈0．05），m糖吸收值显著降低（P〈0．01）；术后5、7d，B组nNOSmRNA表达显著下降（P〈0．001），iNOSmRNA表达明显增强（P〈0．01）。结论在AR过程中，nNOS可能调节了iNOS的表达；nNOS的活性和表达与移植肠管的结构和吸收功能密切相关；iNOS的激活是加重组织损伤的重要因素之一。

Objective To evaluate the role of neuronal （r,NOS） and inducible nitric oxide syn- thase （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 rain, 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 reseeted 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 transeription-polymerase chain reaction （RT-PCR）. Results The survival time in groups A and B was 〉 30 and （6. 83 ＋ 0. 75 ） （lays 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 sig- nificantly （ 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.