Figure 1.
Representative pictures of hepatic lipid staining with Oil red O.
There were no significant differences in lipid accumulation between the control (A) and the quercetin (B) group. The lipid levels were comparable to mice fed a normal-fat diet (C) and much lower than the positive control of hepatic lipid accumulation from mice fed a high-fat diet (D).
Figure 2.
Cumulative serum profile of fatty acids originating from total lipids.
Fatty acids were measured with GC. The levels of palmitic acid (16∶0), oleic acid (18∶1(n-9)), and linoleic acid (18∶2(n-6)) were significant lower in the quercetin group. Data is presented as mean ± SEM. Asterisks indicates a significant difference between the control and the quercetin group; *** p<0.001.
Table 1.
Fatty acid composition of the control and quercetin diet in percentages.
Figure 3.
1H NMR difference spectrum of the quercetin-fed mice minus the control mice.
Serum samples from mice exposed to quercetin minus the 1H NMR spectra of the sera from control mice is represented by the top line. The control group is represented by the middle line and the quercetin group is represented by the lowest line. Two representative parts of the spectrum are presented in the figure. PUFA, poly unsaturated fatty acids; MUFA, mono unsaturated fatty acids; FA, fatty acids; TG, triglycerides; PGLY, phosphoglycerides; PC phosphatidylcholine; EC, esterified cholesterol; TC total cholesterol.
Figure 4.
Percentages of lipids present in serum per mouse plotted for quercetin mice to control mice.
Lipids were measured with 1H NMR. Data is presented as the mean ratio of percentages of lipids present in serum per mouse plotted for quercetin-fed (Q) mice over control (C) mice. Total FFA were not changed, while other PUFA than 18∶2 FA, 22∶6 FA, and, w-3 FA were significantly increased. TG were significantly decreased by the quercetin diet. Data is presented as mean ± SEM. Asterisks indicates a significant difference between the control and the quercetin group; * p<0.05, **p<0.01, *** p<0.001. PUFA, poly unsaturated fatty acids; MUFA, mono unsaturated fatty acids; FA, fatty acids; TG, triglycerides; PGLY, phosphoglycerides; PC phosphatidylcholine; EC, esterified cholesterol; TC total cholesterol.
Figure 5.
Volcano plot of all expressed probes by global hepatic gene expression analysis.
Volcano plot of all probes showing statistics FDR-adjusted p-values plotted against the fold change of each probe (quercetin vs. control). Frames outline genes that are regulated with absolute fold change >1.75 and a FDR-adjusted p-value <0.01; these gene symbols, names and functions are also represented in table 1.
Table 2.
Regulated hepatic genes with an absolute fold change >1.75 and FDR-adjusted p-value <0.01.
Figure 6.
Microarray confirmation by RT-qPCR.
The quercetin (Q) regulated genes Cyp4a14, Cyp4a10, Acot3, Car (Nr1i3) and Por, compared to the control (C) found by microarray analysis were confirmed with RT-qPCR. Data is presented as mean ± SEM (n = 12). Asterisks indicates a significant difference between the control and quercetin group; ** p<0.01.
Figure 7.
Schematic representation of the quercetin-regulated genes involved in ω-oxidation.
Microarray and RT-qPCR analysis showed an up regulation of Cyp4a14, Cyp4a10, Acot3, Por and Car. Quercetin is suggested to activate Car and/or Por (dashed arrow). Activation of the transcription factor CAR can induce the microsomal cytochrome P450 enzymes, CYP4a14, CYP4a10 and CYP4a31, which are important enzymes involved in ω-oxidation. POR is the electron donor for the microsomal cytochrome P450 mixed-function oxidase system. Formed DCA by ω-oxidation are further degraded by peroxisomal β-oxidation to shorter chain fatty acids. ACOT3 is involved in the transport of DCA into the peroxisomes by hydrolysis of long-medium chain fatty acyl-CoA esters to FFA, which can be further transported out of peroxisomes to mitochondria for β-oxidation or excreted in the urine. FA, fatty acids; DCA, dicarboxylic acids.