Finally, we examined the accumulation of Aβin the hippocampus
of the mice to demonstrate that the positive effects of mulberry on
learning and cognition are potentially mediated by the inhibition of
Aβformation. The data obtained showed that the SAMP8 controls
contained significantly higher Aβaccumulation when compared to
SAMR1 controls and that supplementation with ME was able to
reduce the Aβ deposition (Fig. 6). Oxidative stress is strongly
implicated in the progressive decline of cognition associated with
aging and neurodegenerative disorders [50]. It is suggested that
antioxidants such as α-tocopherol and phenolics found in Toona
sinensisRoemor could lessen the memory deterioration and cognition
deficient, possibly much closely involved in their antioxidant capacity
[14,51]. Much importantly, naturally occurring flavonoids, particularly
for anthocyanins, are the new inhibitors againstβ-amyloid aggregation, suggesting that phytochemicals with the particular C6-linkers-C6
structure could be potent inhibitors[52]. Furthermore, Aβ-stimulated
decrease in antioxidant capacity is positively correlated with spatial
cognitive learning impairment of rats; however, administration of
green tea catechins significantly increases antioxidant activity of
plasma and consequently prevents from Aβ-induced cognitive deficits
[53]. In the present study, we observed that isoprostane, which is a
hallmark of lipid oxidation, showed a high tendency of positive
correlation with Aβcontent in hippocampus of SAM mice (r=.277,
P=.057, data not shown), and the cognitive performance was
significantly correlated with Aβexpression negatively (Fig. 7)