ABSTRACT
Objective To study the mechanism of β3 adrenoceptor (β3-AR) activation underlying cholesterol efflux by activating or inhibiting the β3-AR of HepG2 cells.Methods Cultured HepG2 cells were randomly divided into control group,β3-AR agonist group and β3-AR antagonist group.Serum levels of apoA-Ⅰ,apoA-Ⅱ,and β3-AR in supernatant fluid,and cholesterol,free cholesterol,cholesterol ester in HepG2 cells were measured by ELISA.Cholesterol efflux from macrophages was tested by 3H-labled cholesterol.Expressions of ABCA1 and LXRα mRNA and protein were detected by RT-PCR and Western blot respectively.Results The efflux rate of apoA-Ⅰ,cholesterol and cholesterol ester was significantly higher while the serum levels of cholesterol and cholesterol ester were significantly lower and the expression levels of ABCA1 and LXRα mRNA and protein were significantly higher in β3 AR agonist group than in control group.The serum levels of cholesterol and cholesterol ester were significantly higher while the efflux rate of cholesterol and cholesterol ester and the expression levels of ABCA1 and LXRα mRNA and protein were significantly lower in β3-AR antagonist groupt than in β3-AR agonist group (0.49±0.10 vs 1.24±0.02,0.85±0.05 vs 1.32±0.05,0.38±0.01 vs 1.45±0.20,0.08±0.01 vs 0.76±0.02,P＜0.01).Conclusion β3 AR promotes cholesterol efflux by upregulating the expression of apoA-Ⅰin HepG2 cells.