Objective To investigate the effects of early intervention with different doses of hesperetin on learning and memory ability, amyloid beta protein 1-42(Aβ42) and neprilysin (NEP) activity in APPswe/PS1dE9 double transgenic mice. Methods Three month old C57BL/6J wild-type mice were used as control group(0.5% CMC-Na), and three month old APPswe/PS1dE9 double transgenic mice were used as model group, hesperetin low, medium and high dose groups (0, 20, 40 and 80 mg/kg/d), respectively. They were gavaged once a day for 6 months. Morris water maze behavior test was used to observe the learning and memory ability of mice; HE staining was used to observe the morphology of hippocampal neurons; ELISA was used to detect the content of Aβ 42 in serum; Western blot was used to detect the expression of Aβ 42 and neprilysin (NEP) in brain tissue. Results Compared with the control group, the incubation period of mice in the model group was significantly prolonged(P<0.05), the number of crossing platforms was reduced(P<0.05), the neurons in the hippocampal CA1 area were significantly damaged, the serum Aβ42 content was significantly increased(P<0.05), the content of Aβ42 in the brain tissue was significantly increased(P<0.01), and there was no significant difference in the content of NEP. Compared with the model group, the incubation period of mice in the low, medium and high dose groups of hesperetin was significantly shortened(P<0.01). The number of times increased(P<0.01), the morphological structure of hippocampal CA1 neurons was significantly improved, the content of Aβ42 in serum was significantly reduced(P<0.01), the content of Aβ42 in brain tissue was significantly reduced(P<0.01). The NEP content in the medium and high dose group were significantly increased(P<0.01). Conclusion Early intervention of hesperetin could significantly improve the learning and memory ability of APPswe/PS1dE9 double transgenic mice and neuronal damage in hippocampus CA1 area. The mechanism might be related to the increase of NEP activity and the enhancement of Aβ42 metabolism.

Objective To study the effect of hesperetin early prevention on learning and memory ability and its mechanism related to TLR2 、NF-κB in Alzheimer's disease (AD) model mice. Methods Twelve 3-month-old C57/B6 mice were used as blank control group. 48 APP/PS1 double transgenic mice were randomly divided into four groups: model group, low dose group, middle dose group, high dose group (n=12 in each group). The low, middle and high dose groups were given hesperidin 20mg/kg, 40mg/kg and 80mg/kg respectively. The blank control group and the model group were given the same amount of carboxymethylcellulose sodium (each day for 6 months). The learning and memory ability was measured with Morris water maze. HE staining was used to observe the neuronal damage in CA1 region of hippocampus. Western blot was used to detect the contents of TLR2 and NF-κB protein in brain tissue of mice. Results Compared with the blank control group, the escaping latency of the model group was significantly prolonged, the times crossing the hidden platform was significantly decreased (P<0.05), and the neuronal damage in the hippocampal CA1 region was obviously increased. The contents of TLR2 and NF-κB protein were significantly increased (P<0.05). Compared with the model group, the escaping latency of mice in the low, middle and high dose groups was significantly shortened, the times crossing the hidden platform was significantly increased (P<0.05), and the neuronal damage in the hippocampal CA1 region was mild. The content of TLR2 and NF-κB protein decreased significantly (P<0.05). Conclusion Hesperetin early prevention can significantly improve the learning and memory ability and the injury of hippocampal neurons in APP/PS1dE9 mice, and its mechanism might be related to the down-regulation of TLR2 and NF-κB protein expression.