| Objective:To establish a rat model of contrast-induced nephropathy(CIN),and to explore the protective effect of nicorandil on CIN in rats and its molecular mechanism,so as to explore new targets for the prevention or treatment of CIN.Methods:1.Twenty-four SD rats were randomly divided into four groups(n=6): N group,NIC group,CIN group and CIN + NIC.Rats in NIC and CIN+NIC groups were given nicorandil solution by intragastric administration for 7 days.On the fourth day of intragastric administration,rats in CIN and CIN+NIC groups were injected with indomethacin,L-NAME and iopaconol via tail vein at 15 min intervals under isoflurane after 24-hour water deficiency,rats in groups N and NIC were given PBS buffer,normal saline and normal saline successively.2.The 24-hour urine volume was measured at 24,48 and 72 h after iopaconol injection.Urine and Blood were retained for the detection of NGAL,creatinine and Cys-C.Rats were sacrificed 72 h after the iopaconol injection.A renal was used for HE,IHC(Caspase-3)and TUNEL staining.The other kidney was used for RT-PCR and Western blot,whith detect the expression levels of Bax,Bcl-2 and Caspase-3.Results:1.General condition There were no significant difference in body weight and 24hour-urine volume among the four groups at each time point.2.Dynamic changes of various kidney functionindicatorsThere were no significant difference in basal SCr,Ccr,NGAL and Cys-C among the four groups.(1)The Scr of rats in CIN group increased by more than 25% compared with the baseline value within 72 h of CM injection,which met the diagnostic criteria of contrast medium renal injury.After 24,48 and 72 h of modeling,Scr values in CIN group were higher than that of others three groups(all P<0.05),which reached its peak at 48 h of modeling and decreased at 72 h.(2)The Ccr of the three time points in CIN group was significantly lower than that of others three groups(P<0.05).(3)The urinary NGAL values in CIN and CIN+NIC groups continued to increase at 24,48 and 72 h after modeling.The urinary NGAL value of CIN + NIC group is higher than that of N and NIC group,but lower than that of CIN group(all P<0.05).(4)The Cys-C value of CIN+NIC group was higher than that of N and NIC groups at three time points,but lower than that of CIN group(all P<0.05).3.Results of HE staining The renal tubular injury score in CIN group was significantly higher than that in N,NIC and CIN+NIC groups(all P <0.05).Compared with CIN group,pathological renal tubular damage in CIN+NIC group was significantly improved(P<0.05).4.Results of TUNEL staining The apoptotic index of CIN group was not only significantly higher than that of N and NIC groups,but also significantly higher than that of CIN+NIC group(all P<0.05).5.Results of RT-PCR The expression of Bax mRNA and Caspase-3 mRNA in CIN group was significantly higher than that in N group,NIC group and CIN+NIC groups(all P<0.05).Meanwhile,the expression level of Bcl-2 mRNA in CIN+NIC group was higher than that in CIN group(P<0.05).6.Results of IHC staining Although the expression of Caspase-3 in CIN and CIN+NIC groups were higher than that in N and NIC groups(all P<0.05),the expression level of Caspase-3 in CIN+NIC group was significantly lower than that in CIN group after nicorandil intervention(P<0.05).7.Results of western blot The expression level of Bax in CIN + NIC group was higher than that in N and NIC groups(all P<0.05),but lower than that in CIN group(P<0.05).In addition,the expression level of Bcl-2 in CIN group was significantly lower than that in other three groups(all P<0.05).Conclusion:1.The method of inducing CIN model in this experiment is rapidity and simplicity.2.NGAL and Cys-C may assist in early diagnosis of CIN with serum creatinine.3.The expression of Bax and Caspase-3 was up-regulated and Bcl-2 was downregulated in rats of CIN group.Meanwhile,the structure of renal tubule was destroyed and the renal tubular cells showed obvious apoptosis.4.After intervention with nicorandil,the up-regulated Bax,Caspase-3 and downregulated Bcl-2 in CIN rats were reversed to a certain extent,which reduced the damage and apoptosis of renal tubular epithelial cells in CIN rats. |
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