Interplay of curcumin and its liver metabolism on the level of Aβ in the brain of APPswe/PS1dE9 mice before AD onset

Background An increasing number of studies have shown that Alzheimer's disease (AD) is a systemic disease characterized by brain dysfunction. In this study, we aimed to investigate the effects of curcumin on the liver, an important metabolic organ, and on the brain in APP(swe)/PS1(dE9)(APP/PS1) mice, and the interaction between these effects. Methods Curcumin was administered to 5-month-old APP/PS1 transgenic mice for 7 consecutive days using the intragastric (ig) and intracerebroventricular (icv) administration routes, respectively. The object recognition test (ORT) and open field test (OFT) were conducted to evaluate long-term recognition memory and anxiety after curcumin administration. Levels of beta-amyloid (A beta), A beta(42), and interleukin-1 beta (IL-1 beta) in the brain and liver were measured. Results In the ig group, curcumin ameliorated anxiety-like behavior and suppressed the level of A beta(42) in the liver and the total A beta in the brain. In the icv group, curcumin treatment affected the distribution of A beta(42) and IL-1 beta in the brain compared to the liver. There was a significant treatment-region interaction in A beta(42) level for the icv group (F(1, 24) = 17.7,p < 0.001), but no interaction effect for the ig group. Conclusion Our findings show that curcumin administration before A beta deposition shows promise for preventing AD, and further that curcumin may play an important role in the clearance of A beta(42) from the brain to the peripheral circulation.