Objective  To explore the effect and mechanism of oat fiber on intestinal cholesterol metabolism in C57BL/6 mice fed a high-fat/cholesterol diet.

  Methods  Thirty-six 6-week-old male C57BL/6 mice were randomly divided into three groups according to body weight: negative control group, model control group, and oat fiber group. All the mice were treated for 24 weeks. At the end of the experiment, serum triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), fasting blood glucose (FBG) and insulin, and liver homogenate TG and TC were measured. Western blot was used to determine protein expressions involved in intestinal cholesterol metabolism, including liver-X-receptor alpha (LXRα), adenosine triphosphate-binding cassette A1 and G1 (ABCA1 and ABCG1).

  Results  Compared with the model control mice, the mice treated with oat fiber had significantly decreased serum TC (2.02 ± 0.44 mmol/L) and LDL-C (0.54 ± 0.27 mmol/L) but increased serum HDL-C (1.05 ± 0.19 mmol/L) (P < 0.05 for all) and the mice also had obviously decreased FBG (6.68 ± 1.32 mmol/L) and homeostatic model assessment for insulin resistance (HOMA-IR) (3.66 ± 1.28). In addition the protein expressions of LXRα (0.68 ± 0.14), ABCA1 (0.96 ± 0.24) and ABCG1 (0.59 ± 0.15) were upregulated in small intestine tissue of oat fiber treated mice in comparison with those of the mice of the model group (all P < 0.05).

  Conclusion  Oat fiber can improve blood lipid profiles and increase intestinal cholesterol efflux and the effects may be related to upregulations of LXRα, ABCA1 and ABCG1 signaling pathways in intestinal tissue.