ABSTRACT
Objective: To investigate the effects of quercetin on cholesterol accumulation and cholesterol flow in RAW264.7 macrophages and explore the potential mechanism underlying its anti-atherogenic activity. Methods: The inhibitory effect of quercetin on cholesterol accumulation induced by oxidized low-density lipoprotein (ox-LDL) was assessed by oil red O staining and total cholesterol (TC) specific kits in RAW264.7 macrophages. And the action of cholesterol efflux and influx was tested by fluorescent assays. Cholesterol flow-associated genes expression was detected by real-time quantitative PCR (RT-PCR). Results: Quercetin significantly inhibited the cholesterol accumulation. Treatment with quercetin (10 μmol/L) significantly enhanced cholesterol efflux and substantially inhibited cholesterol influx. RT-PCR showed that quercetin significantly increased the mRNA levels of peroxisome proliferator-activated receptor γ (PPARγ), liver X receptor alpha (LXRα), ATP-binding cassette, subfamily A1 (ABCA1) and subfamily G1 (ABCG1), decreased scavenger receptor (SR)-A1 and SR-A2. Conclusion: Quercetin might be a new inhibitor on intracellular cholesterol accumulation. Upregulation of the classical PPARγ-LXRα-ABCA1/ ABCG1 pathway and down-regulation of SR-A1 and SR-A2 may participate in its suppressive effect on intracellular cholesterol accumulation.
ABSTRACT
Objective: To clarify the potential inhibitive effect of epipinoresinol on macrophage foam and potential mechanisms. Methods: The inhibition of epipinoresinol on foam cell formation after stained with oil red O was assessed by Image-Pro Plus and Microplate Reader, and the effect on cholesterol efflux and influx was tested by fluorescence detection to obtain cholesterol inflows-time curve and outflow rate. Additionally the cholesterol flow-associated genes expression was checked by real-time PCR (RT-PCR). Results: Epipinoresinol dose-dependently inhibited the enhanced cholesterol accumulation elicited by oxidized low-density lipoprotein cholesterol (ox-LDL) in RAW264.7 cells. Treatment with epipinoresinol significantly enhanced the cholesterol efflux mediated by high-density lipoprotein (HDL) and substantially inhibited the cholesterol influx. RT-PCR showed that epipinoresinol significantly increased the mRNA levels of PPARγ, LXRα, ABCA1, and ABCG1, decreased those of SR-A1 and SR-A2. Conclusion: Epipinoresinol is a new inhibitor on foam cell formation that may stimulate the cholesterol efflux through up-regulating the PPARγ-LXRα-ABCA1/ABCG1 pathway and prevent cholesterol influx through down-regulating SR-A1 and SR-A2, which may be useful on atherosclerosis treatment.
ABSTRACT
Objective: To investigate the effect of oxLDL on CD36 expression and cholesterol influx in THP-1 macrophage. Methods: THP1 macrophage were treated with 50mg/L oxLDL for 0,12,24,36,48 h respectively.Oil red O staining was used to observe the intracellular lipid droplets.\labeled Cholesterol influx was determined by FJ-2107P type liquid scintillator.CD36 mRNA and protein level were determined by reverse transcription-polymerase chain reaction(RT-PCR) and Western blotting respectively. Results:We found that oxLDL elevated CD36 in both protein and mRNA levels and increased cholesterol influx in a time-dependent manner.The levels of cholesterol influx were 23.5%、(27.8%、)39.7%、44.1% and 49.7% respectively. Conclusion: oxLDL may upregulate CD36 expression and increase cholesterol influx.