Purpose To evaluate the effect of PCSK9 gene knockout on myocardial function in obese mice via ultrasound strain technology,and to discuss the related mechanisms.Materials and Methods Twenty six-week-old wild-type C57BL/6 male mice were selected and randomly divided into a normal group(n=10)and an obese group(n=10).Additionally,ten six-week-old PCSK9-/-C57BL/6 male mice were selected as the PCSK9-/-group.Mice in the obese group and PCSK9-/-group were fed with high-fat feed to create models,while those in the normal group were fed with regular feed.After 12 weeks,mice that were successfully modeled were selected from the obese group and PCSK9-/-group.Then,the three groups of mice were subjected to cardiac ultrasound,transmission electron microscopy and immunofluorescence staining to observe relevant indicators.Results The interventricular septal end-diastolic thickness of mice in obese group,normal group,and PCSK9-/-group were(0.98±0.13)mm,(0.77±0.07)mm,(0.78±0.13)mm,respectively,with statistically significant difference(F=5.10,P=0.02).The obese group was thicker than the normal group(t=2.73,P＜0.05),while the PCSK9-/-group was thinner than the obese group(t=-2.92,P＜0.05).There were statistically significant differences in global longitudinal strain and global circumferential strain of the left ventricle among the three groups(F=7.44,15.40,P＜0.05),with the obese group showing a decrease in global longitudinal strain and global circumferential strain compared to the normal group(t=3.79,5.50,P＜0.05).The PCSK9-/-group showed an increase in global longitudinal strain and global circumferential strain compared to the obese group(t=-2.53,-3.37,P＜0.05).Electron microscopy and immunofluorescence results showed that the myocardial ultrastructure of the obese group was damaged,and the expression of NLRP3 and Caspase-1 were higher than that of the normal group(t=12.53,-4.73,P＜0.05),the myocardial ultrastructure damage in the PCSK9-/-group was significantly improved,the expression of NLRP3 and Caspase-1 were lower than that in the obese group(t=-6.23,2.05,P＜0.05).Conclusion Ultrasound strain can more sensitively detect changes in myocardial function in obese mice with PCSK9 gene knockout compared with conventional cardiac ultrasound parameters.Knockout of the PCSK9 gene may improve myocardial function in obese mice by inhibiting the expression of NLRP3 and Caspase-1.
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