5-Caffeoylquinic Acid Ameliorates Cognitive Decline and Reduces Aß Deposition by Modulating Aß Clearance Pathways in APP/PS2 Transgenic Mice.

The accumulation of amyloid ß (Aß) in the brain is a major pathological feature of Alzheimer's disease (AD). In our previous study, we demonstrated that coffee polyphenols (CPP) prevent cognitive dysfunction and Aß deposition in the brain of an APP/PS2 transgenic mouse AD model. The underlying mechanisms, however, remain to be elucidated. Here, we investigated the effects of the chronic administration of 5-caffeoylquinic acid (5-CQA), the most abundant component of CPP, on cognitive dysfunction in APP/PS2 mice to identify the role of CPP in Aß elimination. Relative to the untreated controls, the mice fed a 5-CQA-supplemented diet showed significant improvements in their cognitive function assessed by Y-maze and novel object recognition tests. Histochemical analysis revealed that 5-CQA substantially reduced Aß plaque formation and neuronal loss in the hippocampi. Moreover, 5-CQA upregulated the gene encoding low-density lipoprotein receptor-related protein 1, an Aß efflux receptor, and normalized the perivascular localization of aquaporin 4, which facilitates Aß clearance along the paravascular pathway. These results suggest that 5-CQA reduces Aß deposition in the brain by modulating the Aß clearance pathways and ameliorating cognitive decline and neuronal loss in APP/PS2 mice. Thus, 5-CQA may be effective in preventing cognitive dysfunction in AD.

Coffee polyphenols prevent cognitive dysfunction and suppress amyloid ß plaques in APP/PS2 transgenic mouse.

Epidemiological studies have found that habitual coffee consumption may reduce the risk of Alzheimer's disease. Coffee contains numerous phenolic compounds (coffee polyphenols) such as chlorogenic acids. However, evidence demonstrating the contribution of chlorogenic acids to the prevention of cognitive dysfunction induced by Alzheimer's disease is limited. The present study investigated the effect of chlorogenic acids on the prevention of cognitive dysfunction in APP/PS2 transgenic mouse model of Alzheimer's disease. Five-week-old APP/PS2 mice were administered a diet supplemented with coffee polyphenols daily for 5 months. The memory and cognitive function of mice was determined using the novel object recognition test, Morris water maze test, and the step-through passive avoidance test. Immunohistochemical analysis revealed that chronic treatment with coffee polyphenols prevented cognitive dysfunction and significantly reduced the amount of amyloid ß (Aß) plaques in the hippocampus. Furthermore, we determined that 5-caffeoylquinic acid, one of the primary coffee polyphenols, did not inhibit Aß fibrillation; however, degraded Aß fibrils. In conclusion, our results demonstrate that coffee polyphenols prevent cognitive deficits and reduce Aß plaque deposition via disaggregation of Aß in the APP/PS2 mouse.