Effects Of Lignans From Eucommia Ulmoides On The Accumulation Of Triglyceride In HepG2Cells

Background:Hypertriglyceridemia is a major risk factor of cardiovascular diseases. There are few drugs in controlling plasma triglyceride clinically. Owing to the defects of drugs in effect and safety treating hypertriglyceridemia, it is significant to develop triglyceride-lowering drugs. Eucommia ulmoides contains many pharmacological activities:anti-hypertension, lipid-lowering, anti-oxidation, anti-atherosclerosis, and myocardial protection. Eucommia Lignans is active fraction extracted from Eucommia Ulmoides, reducing plasma triglyceride in hypertension patients with hyperlipidemia in clinical application. Investigating the effects and the mechanisms of lignans from Eucommia ulmoides on the metabolism of triglyceride will provide evidence for the developing lipid-lowering of Eucommia Lignans and clinic application.Objective:To investigate the effects and the mechanism of lignans from Eucommia ulmoides on the metabolism of triglyceride in HepG2cells incubated in oleic acid.Method:HepG2cells was used in this research.To observed the effect of Eucommia Lignans on the HepG2cells growth, HepG2cells were cultured in vitro in7groups:control,15mg/L,37.5mg/L,75mg/L,150mg/L,300mg/L,600mg/L treated by lignans; then determinate the A490value by MTT one-step detection to assess the number of cells.HepG2cells were cultured in vitro to evaluate the effects and mechanisms of lignans on the accumulation of triglyceride in HepG2cells in6groups:control, OA model (0.5mM OA), low concentration lignans (0.5mM OA+15mg/L lignans), middle concentration lignans (0.5mM OA+30mg/L lignans), high concentration lignans (0.5mM OA+45mg/L lignans), and fenofibrate group (0.5mM OA+100μmol/L fenofibrate). The determination of triglyceride content in the cells was using kits. The mRNA and protein level of PPARou FAS、CPT1A in HepG2were determined by using real-time quantitative polymerase chain reaction method and Western blot.Result:Lignans from Eucommia ulmoides was safe to the proliferation of HepG2incubated with different concentrations lignans(15mg/L～300mg/L). While600mg/L Eucommia lignans inhibited the proliferation of cells signifcantly(0.83±0.17νs1.00±0.08P=0.011).The content of triglyceride increased in HepG2incubated with0.5mM OA compared with the control,(3.13±0.27νs1.00±0.00,P<0.001)；The middle and high concentration of Eucommia Lignans can suppresse intracellular triglyceride accumulation significantly compared with the model group,(2.25±0.12and2.42±0.13νs3.13±0.27,P<0.0001and P<0.001).0.5mM OA induced the expression of CPTlA mRNA in HepG2significantly compared with control(1.62±0.071νs1.00±0.02,P<0.001), while suppressing the PPARα mRNA(0.85±0.10νs1.00±0.03,P=0.019)；The Eucommia Lignans can increase the CPT1A mRNA in different concentration in a dose-dependent manner significantly compared with the model group,(1.89士0.07,2.06±0.11,2.26±0.11νs1.62±0.07,P=0.013,P<0.001,P<0.001)； and PPARα[mRNA in lignans group was increased(1.06±0.05,1.19±0.03,1.24±0.06νs0.85±0.10,P=0.002,P<0.001,P<0.001)；Compared with the model group,fenofibrate increased the level of CPTlA and FAS mRNA(2.78±0.21vs1.62±0.07,P=0.001；1.53±0.15νs0.88±0.19,P<0.001；0.97±0.09vs0.85±0.10,P=0.046),significantly.The protein level of CPTlA and PPARα induced by OA was increased significantly(1.14±0.03νs1.00±0.01,P<0.001and1.22±0.01νs1.00±0.03,P<0.001)；Different concentration of Eucommia Lignans increased the protein level of CPTlA,FAS,PPARα significantly,compared with the model group,(1.42±0.04,1.90±0.01,2.04±0.04νs1.14±0.03,P<0.001,P<0.001, P<0.001in CPTlA；1.11±0.01,1.39±0.01,1.50±0.03νs1.00±0.01,P=0.011,P<0.001,P=0.011in FAS；1.32±0.03,1.52±0.01,1.83±0.04νs1.22±0.01,P<0.001in PPARα)；fenofibrate increased the expression of CPTlA, FAS and PPARα in protein significantly compared with the OA group,(2.51± 0.10νs1.14±0.03, P=0.010,1.21±0.01νs1.00±0.01, P=0.002,1.33±0.02vs1.22±0.01, P<0.001).Conclusions:Lignans from Eucommia ulmoides can suppress accumulation of intracellular triglyceride in HepG2cells, which may be related to the activation of PPARa and the increase of CPTlA, induced the P-oxidation of fatty acid.