| Objective In this study,Ang gene knockout mice were combined with angiotensinⅡminiature osmotic release pump to observe the effect of endoliptin on cardiac hypertrophy at cellular and molecular levels,so as to explore the role of endoliptin in cardiac hypertrophy.Methods1.Experimental groupingA total of 16 SPF-grade 8-week-old male C57BL/6 mice weighing 18murine 26g were randomly divided into two groups:wild group(WT group)and wild angiotensin group(WT AngⅡgroup(n=8 in each group).2.Establishment of cardiac hypertrophy modelAll mice were subcutaneously placed with a miniature release pump.The mice in WT group and KO group were continuously infused with normal saline at the rate of 1.3ml/kg/days,while the mice in WT AngⅡgroup and KO AngⅡgroup were continuously infused with AngⅡof 5mg/ml at the rate of 1.3ml/kg/days.3.Materials and methodsThe mice were fed under standard conditions for 4 weeks.After measuring the body weight of the mice,the mice were killed,and at the same time,the hearts of the mice were quickly taken out,washed for 4 times with normal saline of 4 degrees Celsius,and dried with sterile gauze.The weight of the heart of the mice was weighed,and the heart mass index((HMI))was calculated.The mouse ventricle was cut into two parts,and the upper part was stored in a refrigerator at minus 80 degrees Celsius.The levels ofβ-MHC and BNP expressed in mouse cardiomyocytes were detected by RT-PCR.The lower part was immersed in formalin solution,embedded in paraffin,sliced,dewaxed and applied to HE staining and Masson staining.Several different visual fields were observed and intercepted under optical microscope.Image J was used to measure and analyze the cross-sectional area of mouse cardiomyocytes and the volume fraction of collagen fibers of mouse cardiomyocytes.4.Statistical analysisStatistical analysis was carried out by using Prism5.0 software,and the measurement data were expressed in the form of mean±standard deviation(x±S).Independent sample t-test was used to compare different groups,The difference was statistically significant(P<0.05).Results1.Heart mass index(HMI)The HMI of both AngⅡgroup was higher than that of its control group.KO group/KO AngⅡgroup:(4.18±0.24 vs 5.09±0.47 mg/g,P<0.05).WT group/WT AngⅡgroup(4.18±0.21 vs 5.11±0.59 mg/g,P<0.05).There was no significant difference in HMI between KO group and WT group,KO group/WT group[(4.18±0.24)vs(4.18±0.21)mg/g,P>0.05].Compared with WT AngⅡgroup,the HMI of KO AngⅡgroup was smaller than that of WT AngⅡgroup,but there was no significant difference between,KO AngⅡgroup/WT AngⅡgroup[(5.09±0.47)vs(5.11±0.59)mg/g,P>0.05].2.Cross-sectional area of cardiomyocytesThe cross-sectional area of cardiomyocytes in both AngⅡgroups was larger than that in the control group.KO group/KO AngⅡgroup[(332.90±134.00)vs(407.50±171.40)um~2,P<0.05].Compared with WT AngⅡgroup,WT group[(327.10±112.70)vs(415.60±197.50)um~2,P<0.05];There was no significant difference in cross-sectional area of cardiomyocytes between KO group and WT group,KO group/WT group[(332.90±134.00)vs(327.10±112.700)um~2,P>0.05].The cross-sectional area of cardiomyocytes in KO AngⅡgroup was smaller than that in WT AngⅡgroup,but there was no significant difference between KO AngⅡgroup and WT AngⅡgroup,KO AngⅡgroup/WT AngⅡgroup[(407.50±171.40)vs(415.60±197.50)um~2,P>0.05].3.Volume fraction of collagen fibers in cardiomyocytesThe volume fraction of myocardial collagen fiber in AngⅡgroup was higher than that in its control group.KO group/KO AngⅡgroup[(5.31±1.90)vs(15.16±3.21)%,P<0.05].KO group/KO AngⅡgroup[(5.31±1.90)vs(15.16±3.21)%,P<0.05].There was no significant difference in the volume fraction of collagen fibers between KO group and WT group,KO group/WT group[(5.31±1.90)vs(5.32±1.99)%,P>0.05].The volume fraction of collagen fibers of cardiomyocytes in KO AngⅡgroup was slightly lower than that in WT AngⅡgroup,but there was no significant difference between KO AngⅡgroup and WT AngⅡgroup,KO AngⅡgroup/WT AngⅡgroup[(15.16±3.21)%vs(15.26±3.02)%,P>0.05].4.MRNA expression level ofβ-MHC in cardiomyocytesThere was no significant difference in the expression ofβ-MHC m RNA between KO group and WT group(P>0.05).The m RNA expression level ofβ-MHC in KO AngⅡgroup was significantly higher than that in KO group.The m RNA expression level ofβ-MHC in WT AngⅡgroup was significantly higher than that in WT group.The m RNA expression ofβ-MHC in cardiomyocytes of KO AngⅡgroup was lower than that of WT AngⅡgroup,but there was no significant difference(P>0.05).5.MRNA expression level of BNP in cardiomyocytesThere was no significant difference in BNP m RNA expression between KO group and WT group.The m RNA expression of BNP in cardiomyocytes of KO AngⅡgroup was higher than that of KO group,and the difference was statistically significant.The m RNA expression level ofβ-MHC in WT AngⅡgroup was significantly higher than that in WT group.The m RNA expression of BNP in cardiomyocytes of KO AngⅡgroup was lower than that of WT AngⅡgroup,but there was no statistical significance(P>0.05).Conclusions1 Simple adiponectin gene knockout had no significant effect on mouse cardiomyocytes.2 AngiotensinⅡcould induce hypertrophy of cardiomyocytes in mice,which was characterized by an increase in heart mass index,an increase in cross-sectional area of cardiomyocytes,an increase in the number of collagen fibers and an increase in the expression ofβ-MHC and BNP.3 Adiponectin gene knockout had no significant effect on the process of myocardial hypertrophy induced by angiotensinⅡ. |
