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To investigate the potential preventive effects of metformin on non-alcoholic fatty liver disease (NAFLD) and roles of phospholipase A2/lysophosphatidylcholine pathway in hepatocyte lipoapoptosis in a rat NAFLD model induced by high-fat diet.Male SD rats (n = 36) were randomly divided into three groups with 12 rats in each and treated with different diet and drugs: group I: ordinary diet, group II: high-fat diet, group III: high-fat diet and metformin. Ten weeks later, the rats were sacrificed and their body weight and liver weight were obtained, serum lipid metabolic indexes, insulin resistance indexes and secretory phospholipase A2 (sPLA2), lysophosphatidylcholine (LPC) levels and other parameters were measured. Phospholipase A2 mRNA expression levels were measured by quantitative reverse transcription-polymerase chain reaction (RT-PCR). In addition, the histological changes of liver tissue were analyzed.Compared to ordinary diet group, the rat's liver weight (g) (16.92 ± 2.49 vs. 12.16 ± 0.82), hepatic exponent (0.034 ± 0.004 vs. 0.026 ± 0.002), serum alanine aminotransferase (U/L) (45.43 ± 9.73 vs. 29.42 ± 6.73), triglyceride (mmol/L) (1.22 ± 0.24 vs. 0.85 ± 0.19), cholesterol (mmol/L) (2.00 ± 0.37 vs. 1.49 ± 0.33), lipoprotein(a) (mmol/L) (743.86 ± 32.19 vs. 648.42 ± 78.87), low-density lipoprotein (mmol/L) (1.31 ± 0.35 vs. 0.65 ± 0.22), insulin (mmol/L) (22.16 ± 5.16 vs. 16.86 ± 5.35), insulin resistance index(5.10 ± 1.45 vs. 3.59 ± 0.99), free fatty acid (mEq/L) (0.57 ± 0.10 vs. 0.35 ± 0.07), sPLA2 [µmol/(min·ml)] (0.130 ± 0.016 vs. 0.098 ± 0.024), lysophosphatidylcholine (µmol/L) (707.26 ± 92.48 vs. 508.87 ± 96.50), leptin (pg/ml (80.08 ± 17.73 vs. 65.11 ± 14.09), liver triglyceride (mg/g) (13.57 ± 0.65 vs. 12.03 ± 1.14), cholesterol (mg/g) (2.19 ± 0.15 vs. 1.94 ± 0.12) (P0.05) were significantly increased in high-fat diet group. Moreover, degree of hepatic steatosis was significantly higher and sPLA2 mRNA expression was also significantly increased. Secondly, in comparison with high-fat diet group, early metformin treatment significantly reduced the rat's body weight (g) (394.40 ± 33.10 vs. 491.86 ± 26.45), liver weight (g) (13.24 ± 1.16 vs. 16.92 ± 2.49), serum alanine aminotransferase (U/L) (30.40 ± 4.50 vs. 45.43 ± 9.73), triglyceride (mmol/L) (0.75 ± 0.19 vs. 1.22 ± 0.24), cholesterol (mmol/L) (1.61 ± 0.38 vs. 2.00 ± 0.37), insulin (mmol/L) (16.96 ± 5.60 vs. 22.16 ± 5.16), insulin resistance index (3.75 ± 1.41 vs. 5.10 ± 1.45), sPLA2 [µmol/(min·ml)] (0.101 ± 0.009 vs. 0.130 ± 0.016), lysophosphatidylcholine (µmol/L) (549.92 ± 90.78 vs. 707.26 ± 92.48), liver triglyceride (mg/g) (11.23 ± 1.70 vs. 13.57 ± 0.65), cholesterol (mg/g) (1.97 ± 0.20 vs. 2.19 ± 0.15) (P0.05). Moreover, degree of hepatic steatosis was significantly lower and sPLA2 mRNA expression was also significantly decreased by metformin. Thirdly, when compared to ordinary diet group, metformin could also significantly increase hepatic exponent (0.034 ± 0.004 vs. 0.026 ± 0.002) and low-density lipoprotein level (mmol/L) (0.96 ± 0.34 vs. 0.65 ± 0.22) (P0.05). However, it had no impact on hepatic steatosis and sPLA2 expression (P0.05).It was indicated that metformin has potent effects on improving lipid metabolism and insulin resistance in high-fat diet induced non-alcoholic fatty liver disease rat model. The liver protective mechanisms of metformin in non-alcoholic fatty liver disease may be contributed to down-regulation of secretory phospholipase A2 mRNA expression, decrease in serum secretory phospholipase A2, lysophosphatidylcholine, lower inflammatory response and protect mitochondrial function.

AIM: To investigate if non-alcoholic fatty liver disease (NAFLD) is an early mediator for prediction of metabolic syndrome, and if liver B-ultrasound can be used for its diagnosis. METHODS: We classified 861 obese children (6-16 years old) into three subgroups: group 0 (normal liver in ultrasound and normal transaminases); group 1 (fatty liver in ultrasound and normal transaminases); and group 2 (fatty liver in ultrasound and elevated transaminases). We measured the body mass index, waist and hip circumference, blood pressure, fasting blood glucose, insulin, homeostasis model assessment of insulin resistance (HOMA-IR), whole-body insulin sensitivity index (WBISI), lipid profile and transaminases in all the participants. The risk of developing metabolic syndrome (MS) was assessed according to the degree of liver fatty infiltration based on the B-ultrasound examination. RESULTS: Among the 861 obese children, 587 (68.18%) were classified as having NAFLD, and 221 (25.67%) as having MS. The prevalence of MS in NAFLD children (groups 1 and 2) was 37.64% (221/587), which was much higher than that in non-NAFLD group (group 0, 12.04%) (P < 0.01). There were significantly higher incidences concerning every component of MS in group 2 compared with group 0 (P < 0.05). The incidence of NAFLD in MS patients was 84.61% (187/221), which was significantly higher than that of hypertension (57.46%, 127/221) and glucose metabolic anomalies (22.62%, 50/221), and almost equal to the prevalence of dyslipidemia (89.14%, 197/221). Based on the B-ultrasound scales, the presence of moderate and severe liver fatty infiltration carried a high risk of hypertension [odds ratio (OR): 2.18, 95% confidence interval (95% CI): 1.27-3.75], dyslipidemia (OR: 7.99, 95% CI: 4.34-14.73), impaired fasting glucose (OR: 3.65, 95% CI: 1.04-12.85), and whole MS (OR: 3.77; 95% CI: 1.90-7.47, P < 0.01). The state of insulin resistance (calculated by HOMA-IR and WBISI) deteriorated as the degree of fatty infiltration increased. CONCLUSION: NAFLD is not only a liver disease, but also an early mediator that reflects metabolic disorder, and liver B-ultrasound can be a useful tool for MS screening.