Effect of high-fat diet on cholesterol metabolism in rats and its association with Na⁺/K⁺-ATPase/Src/pERK signaling pathway.
| Intervention | Direction | Endpoint | Population | Dosage | Impact | Claim # |
|---|---|---|---|---|---|---|
high-fat diet | increase | serum TC levels | male SD rats | P<0.01 | were significantly higher | #1 |
high-fat diet | increase | serum TG levels | male SD rats | P<0.01 | were significantly higher | #2 |
high-fat diet | increase | serum LDL-C levels | male SD rats | P<0.01 | were significantly higher | #3 |
high-fat diet | decrease | serum HDL-C level | male SD rats | P<0.01 | was significantly lower | #4 |
high-fat diet | increase | cholesterol content in the cytoplasm | male SD rats | - | led to an increase | #5 |
high-fat diet | increase | cholesterol content in the cell membrane | male SD rats | - | led to an increase | #6 |
high-fat diet | increase | ratio of cholesterol content in cytoplasm to that in cell membrane | male SD rats | - | was elevated | #7 |
high-fat diet | decrease | expression of HMG-CoA reductase at mRNA level | male SD rats | P<0.05 | was significantly suppressed | #8 |
high-fat diet | decrease | expression of HMG-CoA reductase at protein level | male SD rats | P<0.05 | was significantly suppressed | #9 |
high-fat diet | decrease | expression of SREBP-2 at mRNA level | male SD rats | P<0.05 | was significantly suppressed | #10 |
high-fat diet | decrease | expression of SREBP-2 at protein level | male SD rats | P<0.05 | was significantly suppressed | #11 |
high-fat diet | increase | Na(+)/K(+)-ATPase α1 | male SD rats | P<0.05 | promoted the expression | #12 |
high-fat diet | decrease | Src-PY418 | male SD rats | P<0.05 | suppressed the phosphorylation | #13 |
high-fat diet | decrease | ERK1/2 | male SD rats | P<0.05 | suppressed the phosphorylation | #14 |
Abnormal cholesterol metabolism is associated with an elevated risk of developing atherosclerosis, hypertension, and diabetes etc. Na(+)/K(+)-ATPase was found to regulate cholesterol synthesis, distribution and trafficking. This study aimed to examine the effect of high-fat diet on cholesterol metabolism in rats and the role of Na(+)/K(+)-ATPase/Src/ERK signaling pathway in the process. Forty male SD rats were evenly divided into high-fat diet group and control group at random. Animals in the former group were fed on high-fat diet for 12 weeks, and those fed on basic diet served as control. Blood lipids, including total cholesterol (TC), triglyceride (TG), high density lipoprotein-cholesterol (HDL-C), and low density lipoprotein-cholesteral (LDL-C) levels, were detected at 3, 6 and 12 weeks. The ratio of cholesterol content in cytoplasm to that in cell membrane was detected in liver tissues. RT-PCR and Western blotting were used to measure the expression of lipid metabolism-associated genes (HMG-CoA reductase and SREBP-2) after 12-week high-fat diet. Na(+)/K(+)-ATPase/Src/ERK signaling pathway-related components (Na(+)/K(+)-ATPase α1, Src-PY418 and pERK1/2) were also measured by Western blotting. The results showed that the serum TC, TG, and LDL-C levels were significantly higher in high-fat diet group than those in control group, while the HDL-C level was significantly lower in high-fat diet group at 6 weeks (P<0.01). High-fat diet led to an increase in the cholesterol content in the cytoplasm and cell membrane. The ratio of cholesterol content in cytoplasm to that in cell membrane was elevated over time. The expression of HMG-CoA reductase and SREBP-2 was significantly suppressed at mRNA and protein levels after 12-week high-fat diet (P<0.05). Moreover, high-fat diet promoted the expression of Na(+)/K(+)-ATPase α1 but suppressed the phosphorylation of Src-PY418 and ERK1/2 at 12 weeks (P<0.05). It was concluded that high-fat diet regulates cholesterol metabolism, and Na(+)/K(+)-ATPase signaling pathway is involved in the process possibly by regulating the expression of lipid metabolism-associated proteins HMG-CoA reductase and SREBP-2.