| Objective:To explore whether diet with different saturated fat content has direct effects on lipid metabolism and risk factors of cardiovascular disease(CVD),and to further explore its mechanism,so as to provide theoretical basis for dietary fat related dietary guidance in healthy adults.Methods:Healthy C57BL/6 mice aged 12-14 weeks with normal blood glucose and moderate body weight were selected as experimental mice.The mice were fed in SFA grade environment with temperature range of 23-25 ?.The experimental animals were randomly divided into 4 groups.Mice were fed with normal diet or diets containing different concentrations of saturated fat,that is,normal diet group,10% saturated fat group,20% saturated fat group,30% saturated fat content group,there are 10 mice in each group,and 8 weeks of food intervention.At the end of the intervention,body weight was measured,fasting for 12 hours,left ventricular ejection function measured by M-mode echocardiography in small animals,serum triglyceride and cholesterol levels were measured by eyeball sampling.The calcium transient was measured in isolated cardiomyocytes,and the amplitude of calcium transient change(F/F0)and calcium recovery rate in myocardial cells were measured.The mRNA expression of FABP3 gene,the mRNA expression of FABP4 gene in adipose tissue,the content of FABP3 in cardiomyocytes and the content of FABP4 in adipose tissue were detected.Results:1.The results of body weight and blood glucose: The weight gain of mice in each saturated fat content group was higher than that in the control group.The body weight gain of the 10% saturated fat content group was about 106% more than that of the control group and there was a significant difference between the 10% saturated fat content group and the control group(P<0.05).The body weight gain of the 30% saturated fat content group was about 87% more than that of the control group,and there was a significant difference between the 30% saturated fat content group and the control group(P<0.05).Compared with the control group,the terminal blood glucose in the saturated fat content group increased with the increase of fat content,and there was no significant difference between the two groups(P>0.05).2.Blood lipid results: The serum cholesterol level of mice in each saturated fat content group was higher than that in the control group.The serum cholesterol level in 30% saturated fat content group was 28% higher than that in control group,and there was a significant difference between the 30% saturated fat content group and the control group(P<0.05),There was no significant difference in serum cholesterol levels between 10% and 20% saturated fat content groups compared with the control group(P>0.05).Compared with the control group,the serum triglyceride level of each hyperlipidemic group had no significant difference(P>0.05).3.Results of echocardiographic examination of cardiac function: The left ventricular ejection fraction(LVEF)of mice in each saturated fat content group was lower than that in the control group.The left ventricular ejection fraction of the 10% saturated fat content group was 10% lower than that of the control group,and there was a significant difference between the 10% saturated fat content group and the control group(P<0.05).There was no significant difference in ejection fraction between the 20% and 30% saturated fat groups compared with the control group(P>0.05).4.Results of calcium transient in cardiomyocytes: Compared with the control group,the calcium transient amplitude of each saturated fat content group had no significant difference(P>0.05).Compared with the control group,the calcium recovery rate in the 10% saturated fat content group increased by 22%(P<0.05),and that in the 20% saturated fat content group increased by 33% compared with the control group,and the calcium recovery rate in the 10% saturated fat content group was 33% higher than that in the control group.The difference was statistically significant(P < 0.05).Compared with the control group,the 30% saturated fat content group increased by 33%,the difference was statistically significant(P<0.05).5.FABP3 expression level results: Compared with the control group,the expression of FABP3 mRNA in the 30% saturated fat content group increased by 24 %,and there was a significant difference between the 30% saturated fat content group and the control group(P<0.05),but the expression of FABP3 mRNA in 10% and 20% saturated fat group had no significant difference(P>0.05).There was no significant difference in the expression of FABP3 protein in cardiomyocytes between the saturated fat content groups and the control group(P>0.05).6.FABP4 expression level results: There was no significant difference in the expression of FABP4 mRNA between the 10% saturated fat content group and the control group.The mRNA expression of FABP4 in the 20% saturated fat content group was 72% higher than that in the control group,and there was a significant difference between the 20% saturated fat content group and the control group(P<0.001).The expression of FABP4 mRNA in adipose tissue of 30% saturated fat content group was 52% higher than that of control group,and there was a significant difference between the 30% saturated fat content group and the control group(P<0.05).There was no significant difference in the expression of FABP4 protein between the 10% saturated fat content group and the control group(P>0.05).Compared with the control group,but the 20% saturated fat content group increased by 81% compared with the control group,and the difference was statistically significant(P<0.05).Compared with the control group,the 30% saturated fat content group increased by 67%,the difference was statistically significant(P<0.05).7.Comparison of calcium transient and contraction of cardiomyocytes incubated with 0.5 nmol/L FABP3 and 0.5 nmol/L FABP4: the inhibition amplitude of calcium transient in cardiomyocytes incubated with 0.5 nmol/L FABP3 tended to be consistent with that of contraction.The amplitude of inhibition of calcium transient in cardiomyocytes incubated with 0.5nmol/L FABP4 was not obvious,but significantly inhibited the amplitude of contraction.Conclusions:1.Eating 10%,20%,and 30% saturated fat diets for eight weeks increased weight and blood sugar,increased blood lipids and increased the risk of cardiovascular disease.2.A diet of 10%,20%,and 30% saturated fat for 8 weeks had a certain effect on cardiac function and had a negative effect on the contraction of cardiomyocytes.3.Dietary intake of 10%,20% and 30% saturated fat for 8 weeks increased the expression of FABP4,a physiological and pathological biomarker for metabolic and cardiovascular diseases.4.10%,20%,and 30% saturated fat diet directly reduces cardiac function by up-regulating the expression of FABP4. |
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