Objective  To study the effect of red yeast rice (monacolin K) on intestinal barrier function in ApoE-/- rats.

  Methods  Eighteen 8-week-old male ApoE^-/- mice were fed with feeds containing 15% lard and 0.25% cholesterol to establish atherosclerosis model and then randomly divided into a model (with daily gavage of saline), a statin control (10 mg/kg.d statin), and a red yeast rice group (0.34 g/kg.d monacolin K) and 6 male 8-week-old C57BL/6J rats were used as normal control for a 12-week experiment. The aorta specimens were stained with oil red O to quantify the area of plaque; pathological changes of the small intestine were observed with hematoxylin-eosin (HE) staining; the ultrastructure of the small intestine was observed with transmission electron microscopy; and Western blot (WB) was used to detect the expression of tight junction protein zonula occludens-1 (ZO-1) and claudin-1 in colon tissues.

  Results  No aorta plaque formation was observed in the normal control group. The average aorta plaque area for the atherosclerosis model group was 22.46 ± 8.33%. Compared with the normal control group, the mean height of colonic villi (66.27 ± 6.38 μm) and the mean length of colonic microvilli (0.67 ± 0.19 μm) of the model group were significantly decreased compared with those of the normal control group (both P < 0.05) and the mean height of colonic villi (92.57 ± 7.37 μm) and the length of colonic microvilli (0.87 ± 0.07 μm) of the monacolin K group increased significantly (both P < 0.05) in contrast to those of the model group. The protein expression of claudin-1 (494 ± 47.15) and ZO-1 (466.67 ± 43.41) of the model group were significantly lower than those of the normal control group (both P < 0.05). Compared with the model group, the protein expression level of claudin-1 (709.33 ± 60) and ZO-1 (785.67 ± 101.55) in the colonic tissues of the monacolin K group increased significantly in comparison with those of the model group (both P < 0.05). There were no significant differences in all the indicators between monacolin K group and the statin group (P > 0.05 for all).

  Conclusion  Red yeast rice can improve intestinal barrier function in ApoE^-/- rats and the mechanism of the effect may be related to the repairment of colonic villi and the up-regulation of colonic ZO-1 and claudin-1 tight junction proteins.