High‑cholesterol diet results in elevated amyloid‑β and oxysterols in rats

The aim of the present study was to investigate the effects of diet cholesterol on oxysterol levels and amyloid‑β (Aβ) production in the peripheral blood and the brains of Sprague‑Dawley (SD) rats. SD rats were randomly divided into five groups and fed 0.015, 0.05, 0.2, 0.5 and 1.6% cholesterol‑containing diets for 8 weeks. The effect of the different diets on the levels of cholesterol, oxysterols [including 27‑hydroxycholesterol (OHC), 24S‑OHC, 7α‑OHC and 7β‑OHC], and the Aβ1‑40 and Aβ1‑42 peptides were examined in the plasma and the brain of the rats. The results demonstrated that diet cholesterol increased the levels of plasma cholesterol in a dose‑dependent manner. The plasma levels of 27‑OHC, 7α‑OHC and 7β‑OHC significantly increased in the 0.5 and 1.6% cholesterol diet groups and the brain levels of 27‑OHC significantly increased in the 1.6% cholesterol diet group. Increased concentration of cholesterol in the diet had no significant influence on plasma and brain levels of 24S‑OHC in the rats. In addition, Aβ1‑40 and Aβ1‑42 levels in plasma and brain were significantly elevated following administration of 0.5 and 1.6% diet cholesterol. The present study revealed that high diet cholesterol contributed to increased level of oxysterols, especially 27‑OHC, in the peripheral blood and the brain, which may be the link between increased peripheral cholesterol and brain Aβ production.