Inhibitory effect of schisandrin B on free fatty acid-induced steatosis in L-02 cells

AIM：To investigate the effects of schisandrin B （Sch B） on free fatty acid （FFA）-induced steatosis in L-02 cells.METHODS：Cellular steatosis was induced by incubating L-02 cells with a FFA mixture （oleate and palmitate at the ratio of 2：1） for 24 h.Cytotoxicity and apoptosis were evaluated by 3-（4,5-dmethylthiazol-2-yl）-2,5-diphenyl tetrazolium bromide assay and Annexin V/propidium iodide staining,respectively.Cellular total lipid was determined using a photocolorimetric method after Nile red staining,and triglyceride content was measured using an enzymatic kit.To study the effects of Sch B on steatosis,L-02 cells were treated with Sch B （1-100 μmol/L） in the absence or presence of 1 mmol/L FFA for 24 h,and cellular total lipid and triglyceride levels were measured.To explore the mechanisms of action of Sch B in the steatotic L-02 cells,mRNA levels of several regulators of hepatic lipid metabolism including adipose differentiation related protein （ADRP）,sterol regulatory element binding protein 1 （SREBP-1）,peroxisome proliferator-activated receptor （PPAR）-α and PPAR-γ were measured by quantitative real-time polymerase chain reaction （PCR）,and protein levels of ADRP and SREBP-1 were measured by immunoblotting.RESULTS：Treatment with 1 mmol/L FFA for 24 h induced intracellular lipid accumulation in L-02 cells comparable to that in human steatotic livers without causing apparent apoptosis and cytotoxicity.Sch B mitigated cellular total lipid and triglyceride accumulations in the steatotic L-02 cells in a dose-dependent manner.Quantitative real-time PCR and Western blot analyses revealed that treatment of L-02 cells with 100 μmol/L Sch B reverted the FFA-stimulated up-regulation of ADRP and SREBP-1.CONCLUSION：Sch B inhibits FFA-induced steatosis in L-02 cells by,at least in part,reversing the up-regulation of ADRP and SREBP-1.