Résumé
Aim To investigate the effect of orientin on proliferation and differentiation of 3T3-L1 pre-adipocytes and on insulin resistance(IR) in 3T3-L1 adipocytes and the possible mechanisms.Methods MTT assay and oil red O staining were applied to investigate the proliferation and the differentiation of 3T3-L1 pre-adipocytes, respectively.The intracellular triglyceride(TG) contents were detected by enzymatic analysis.IR model was induced with dexamethasone.A fluorescent glucose analogue, 2-NBDG, was used to measure the rate of glucose uptake.Western blot was used to detect the protein level of GLUT4 and phosphorylation of AMPK and ACC.The GLUT4 translocation was measured by fluorescent-immunohistochemistry.Results Orientin decreased the formation of lipid droplets and intracellular TG contents(P<0.01) in a concentration-dependent manner(P<0.05), but it had no obvious effects on the cell vitality.Under the IR state, orientin significantly increased 3T3-L1 adipocytes glucose uptake(P<0.05).Meanwhile, orientin up-regulated the protein expression of p-AMPK, p-ACC, and enhanced GLUT4 translocation and its expression.Conclusion Orientin can effectively inhibit the differentiation of 3T3-L1 pre-adipocytes and increase insulin sensitivity due to the activation of AMPK/GLUT4 signal pathway.
Résumé
A novel method was established for the qualitative and quantitative determination of fatty acids in Channel Catfish muscle by gas chromatography-electron ionization-mass spectrometry (GC-EI-MS) after supercritical carbon dioxide fluid extraction (SFE-CO_2). The extraction parameters for the methodology were optimized). The optimal conditions were extraction pressure of 25 MPa at 45 ℃ and extraction time of 100 min at the rate of carbon dioxide 30 L/h. The fatty acids in the muscle oil were derived by boron-trifluoride method). The saponification time was 10 min, and the esterication time was 20 min. The obtained fatty acid methylesters were separated by gas chromatography using a HP-Innowax capillary column, and were detected by electron) ionization) mass spectrometry. Full scan mode and SIM mode were used for the qualitative and quantitative analysis), respectively. In the SIM mode, saturated fatty acids were determined with m/z 74, mono-unsaturated) fatty acids were determined with m/z 55, double-unsaturated fatty acids were determined with m/z 67, and polyunsaturated fatty acids were determined with m/z 79. The detection limits of 14 fatty acids were 2.2-20.0 μg/L(S/N=3)), and the quantitative limits were 7.39-59.85 μg/L(S/N=10). The recoveries fell in the range from 90.0% to 111.2%(n=4), and the relative standard deviation was between) 2.0% and 5.9%. This effective, sensitive and reproducible method can be used for the determination of fatty acids in Channel Catfish muscle sample.