| Objective: To observe the changes of SOX9 expression in myocardial tissue after acute myocardial infarction in rats,and clarify the relationship between SOX9 and myocardial injury markers,inflammatory factors and ischemic myocardial damage.Methods: Adult male SPF SD rats weighing 250~300g were randomly divided into two groups: myocardial infarction group(MI group)and Sham group(Sham group).The MI group was established by ligating left anterior descending branch of the coronary artery,while the Sham group only threaded the left anterior descending coronary artery without ligation.At the end of 0.5h,8h and 24 h after the successful establishment of the model,the two groups respectively:(1)Cardiac function was evaluated by cardiac ultrasound;(2)Myocardial infarction area was measured by TTC staining;(3)Ultrastructure of myocardial mitochondria in rats was observed by transmission electron microscopy and mitochondrial Flameng score.(4)Serum was collected to detect myocardial injury markers: hs-c Tn,CKMB,Mb and inflammatory factors: expression of IL-6 and TNF-?;(5)The expression of SOX9 in rat myocardium was detected by RT-PCR and Western-blot methods.Results:1.Survival of rats: In MI group,15 rats were established at 0.5h,14 rats survived;15 rats were established at 8h,12 rats survived;15 rats were established at 24 h,11 rats survived.A total of 36 rats in sham group were established at each time point and 36 rats survived.2.The changes of cardiac ultrasound in each group: there was no significant difference in LVEF,LVFS,LVIDd,LVIDs and other cardiac function indexes in sham group.Compared with the Sham group,LVEF,LVFS,LVAWs,and LVAWd decreased and LVIDs and LVESV increased at each time point in the MI group(P<0.05),while there were no differences in the changes of LVPWd,LVPWs,LVIDd,and LVEDV.Compared with 0.5h in the MI group,LVEF and LVFS decreased,LVIDs and LVESV increased at 8h(P<0.05),while LVEF and LVFS increased at 24h(P<0.05)and LVIDs,LVESV showed a decrease(P<0.05).There was no difference in other indicators;In addition,compared with 0.5h,there was no significant difference in all cardiac function indicators in the MI group at 24h(P>0.05).3.The area of myocardial infarction in each group of rats: no myocardial infarction was found in Sham group at each time point.Compared with the Sham group,there were different degrees of myocardial infarction in MI group,and the myocardial infarction area increased gradually at 0.5 h,8 h and 24 h in MI group(P<0.05).4.Results of myocardial ultrastructure and myocardial mitochondria Flameng scores of rats in each group:(1)The results of ultrastructure of myocardial mitochondria: in sham group,the number of mitochondria was large,the structure was complete and clear,the muscle fibers were arranged orderly,the Z-line and light dark band were clear and regular at 0.5h,8h and 24 h At 0.5h,the electron density in the mitochondrial matrix of the MI group decreased slightly,and other results had no significant changes;At 8h,the number of mitochondria decreased,some of the mitochondria swelled and the membrane was destroyed,mitochondria became shorter,shallower and broken,the electron density in the matrix decreased significantly,and some muscle fibers were dissolved and broken.At 24 hours,the number of mitochondria decreased significantly,and the structure of the remaining mitochondria was swollen and vacuolated,and the muscle fibers were dissolved and broken into clusters.(2)Flameng score of myocardial mitochondria: there was no significant difference in the score of myocardial mitochondria at each time point between Sham group and Sham group(P>0.05);There was no significant difference in 0.5h mitochondrial score between MI group and sham group,and the mitochondrial score increased significantly at 8h and 24h(P<0.05);Compared with 0.5h in MI group,the score of mitochondrial increased at 8h and 24h(P<0.05),and the score at 24 h was higher than that at 8h(P<0.05).5.Changes of the markers of serum myocardial injury and inflammatory factors of rats in each group: there was no significant difference in the levels of hs-c Tn,CK-MB,Mb,IL-6 and TNF-? in sham group(P>0.05).Compared with sham group,the levels of IL-6 and TNF-? in MI group increased at 8h and 24h(P<0.05),but the levels of IL-6 and TNF-? in MI group increased at 0.5h(P<0.05),but there was no difference in hs-c Tn,CK-MB and Mb(P>0.05);In MI group,all the markers of serum myocardial injury and inflammatory factors increased at 8h and 24h(P<0.05).6.The expression of SOX9 m RNA and protein in myocardium of rats in each group: there was no difference in the expression of SOX9 m RNA and protein at each time point in the Sham group.Compared with the Sham group,the expression of SOX9 m RNA and protein in MI group had no significant change at 0.5 h(P>0.05),while SOX9 m RNA decreased at 8h and 24 h,and the expression of SOX9 m RNA at 8 h and 24 h in MI group was lower than that at 0.5 h(P<0.05).However,there was no significant difference between 8h and 24h(P>0.05).Compared with the Sham group,the expression of SOX9 protein in the MI group showed a general downward trend,while there was significant difference at 24h(P<0.05),and the expression at 24 h in MI group was lower than that at 0.5 h(P<0.05),There was no significant difference among 0.5h,8h and 24h(P>0.05).7.The results of correlation analysis between the relative expression of myocardial SOX9 protein,the markers of serum myocardial injury and inflammatory factors in each group of rats: With the prolongation of ischemic time in AMI,the expression of SOX9 protein in ischemic myocardium decreased gradually at 24 h,while the markers of serum myocardial injury and inflammatory factors increased gradually.There was a negative correlation between the protein changes of SOX9,the markers of serum myocardial injury and inflammatory factors in serum(the correlation values were:(hs-c Tn,r =-0.641;CK-MB,r =-0.707;TNF-?,r =-0.722;IL-6,r =-0.684)(P<0.05).Conclusion:Within 24 h of AMI:1.The expression of SOX9 in ischemic myocardium decreased,which may be related to the degree of myocardial damage.2.It can lead to the increase of serum myocardial injury markers such as hs-c Tn,CK-MB,Mb,inflammatory factors such as IL-6 and TNF-?,the changes of myocardial injury markers and inflammatory factors can indirectly reflect the damage of myocardial SOX9 protein(negative correlation);3.The local myocardial damage can affect the overall systolic function of the heart,while the changes of cardiac function cannot truly reflect myocardial damage in a certain period of time,and there is a self-regulating mechanism of cardiac function in vivo. |
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