Objective To investigate the effect of mono (2-ethylhexyl) phthalate (MEHP) on cholesterol content in hepatocytes and to provide evidences to researches on the mechanism of hepatic toxicity of MEHP.
Methods HepG2 cells were treated with MEHP at various dosages (0.8, 4.0, 20.0, and 100.0 μmol/L for intra-hepacellular and extra-hepacellular total cholesterol TC and free cholesterol FC test; 0.01, 1.00, 10.00, and 100.00 μmol/L for tests of endonuclear sterol regulatory element binding protein 2 SREBP-2 and cellular cholesterol metabolism-related proteins), Dulbecco′s modified Eagle′s medium (DMEM) as negative control and 1 mmol/L oleic acid (OA) for 24 and 48 hours, respectively. CHOD-PAP-POD enzymatic method was used to detect intra-hepacellular and extra-hepacellular TC and FC; the expression of SREBP-2 was measured with immunocytochemistry; protein expressions of hydroxymethylglutaryl coenzyme A reductase (HMGCR), low density lipoprotein receptor (LDLR) and cholesterol acyltransferase (ACAT1) were determined with Western blot.
Results After 24 hours′ treatment of 100 μmol/L MEHP, the intracellular FC (0.508 ± 0.069 mmol/g) was significantly higher than that of the negative control cells (P < 0.05); the endonuclear nSREBP-2 expressions increased obviously in all MEHP-treated cells and in positive control cells compared with that of the negative control cells. After 48 hours′ treatment, the intracellular FC returned to normal levels (P > 0.05); while, the intra-hepacellular expressions of nSREBP-2 and HMGCR decreased significantly in all MEHP exposed HepG2 cells in comparison with those in the negative control cells (all P < 0.05).
Conclusion MEHP has a certain interference effect on cholesterol metabolism in hepatocytes, but the effect is reversible.
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