| BackgroudWith economic developing in high speed and the aging process speeding up, the prevalence rate of dementia was rising. By2040,the number of elderly sufferers of dementia in our nation will be equivalent to the total number of sufferers in developed countries. Now in our country, there are130millions elder people, and in which there are5-6millions people suffering dementia. By the middle of the21st century, elderly population may reach400millions and the population of dementia sufferers will reach16-20millions. By then, dementia will be an important healthy problem of public.There are abundant theories, practical experience and potential advantage to apply Chinese medicine to treat dementia. Also, it is important practical significance to explain the mechanism, develop a drug to slow the progress of dementia and improve the life quality for the patients.Researches showed that β-asarone could improve the learning ability of modle animals and have an effect of protecting the neuron of AD brains. The pharmalogical mechanism of β-asarone may have an relationship with its effect of attenuating apoptosis of neuron. To assure its therapeutic effect on animals of AD modle and the mechanism to attenuate neuron apoptosis, our study respectively used the APPswe/PSldE9double transgenic mice and glutamate-induced PC12cells to discuss the pharmacological action and pharmacological mechanism of β-asarone.ObjectiveThe present study intend to explore the effect of β-asarone on learning and memory in APPswe/PSldE9double transgenic mice and the effect on PI3K/Akt/Bcl-2singnaling pathway.Method In vivo:55male APPswe/PS1dE9double-transgenic mice aged at4.5months were divided randomly into model group,β-asarone treated(21.2mg/kg per day;42.4mg/kg per day;84.8mg/kg per day;) group and donepezi treated(2mg/kg per day) group. In addition,12male with the same age and background B6mice were used as control. Distilled water was administered to the control group and model group. All mice were oral administered by the drugs from4.5to7months of age. After2.5months of treatment, spatial learning and memory was measured by Morris Water Maze and Step-through Test. The amyloid precursor protein in the cortex from mice were detected by Western blot.In vitro:PC12cells were cultured and exposed to25mmol/l glutamate in the absence or presence of β-asarone. In addition, the potential contribution of the PI3K/Akt neuroprotective pathway in β-asarone-mediated protection against glutamate-induced neurotoxicity was also investigated. The results measured by MTT assay, synapse counting and western blot.Result1. Result in vivo(1) Compared with normal B6mice(normal group), the total swim path length of APPswe/PS1dE9double-transgenic mice (model group) was significantly longer in place navigation test(P<0.01, day5), and the error times was also significantly increased(P<0.05). Treatment with mid-does β-asarone significantly decreased the total swim path length and error times of APPswe/PS1dE9double-transgenic mice(P<0.05). But the donepezil group and high-does β-asarone group only showed a trend of improving the ability of APPswe/PS1dE9double-transgenic mice(P>0.05).(2)7months old double-transgenic mice expressed more APP than normal B6mice in their cortices(P<0.01). And treatment with donepezil and β-asarone didn’t decrease expression of APP in cortices of double-transgenic mice(P>0.05).(3) The expression of p-Akt/Akt was more in cortices of double-transgenic mice than of normal B6mice(P<0.05). And the expression of p-Akt/Akt in all of the donepezil group, low-does β-asarone group and mid-does β-asarone group was decreased(P<0.05).(4) The expression of Bcl-2/Bax was more in cortices of double-transgenic mice than of normal B6mice(P<0.01).β-asarone of mid-does could increase the expression of Bcl-2/Bax(P<0.05). And the donepezil group and high-does β-asarone group only showed a trend of increasing the expression of Bel-2/Bax (P>0.05).2.Result in vitro(1) Glutamic acid of25mmol/L could reduce the survival rate of PC12cells at3h,6h,12h and24h.Treatment with β-asarone of3.125-100umol/L didn’t inhibited the cytotoxicity of induced by glutamate at different time point (P>0.05), but β-asarone of6.25umol/L、12.5umol/L and25umol/L showed a thrend of increasing the survival rate of glutamate-induced PC12cells.(2) Treatment of glutamic acid of25mmol/L for3h could reduce the rate of attachment of PC12cells, and inhibit the growth of synaptic. It was a significant trend of growth inhibition when glutamic acid induced PC12cells for6h(P>0.05). β-asarone showed a trend of promoting synapse growth of PC12cells which was induced by glutamic acid for3h, but it also showed a trend of inhibiting synapse growth after3h(P>0.05).(3) Compared with normal PC12cells, The expression of p-Akt/Akt was less in glutamate-induced PC12cells (P<0.01), and so as the expression of p-Akt/Akt p-Akt/Akt and Bcl-2/Bax in glutamate-induced PC12cells (P<0.01).β-asarone of25umol/L could also increase the expression of Bcl-2/Bax in (P<0.01), but only show a trend of increasing the expression of p-Akt/Akt.Conclusion(1) Learning ability of APPswe/PS1dE9double-transgenic mice is abnormal. Treating APPswe/PS1dE9double-transgenic mice of4.5month old with β-asarone of42.4mg/kg/d for2.5months could improve its spatial memory and learning.(2) β-asarone can’t decrease expression of APP, and it improves learning ability of APPswe/PS1dE9double-transgenic mice by attenuating neroual apoptosis in cortex.(3) β-asarone can inhibit apoptosis of cells via activating the PI3K/Akt/Bcl-2signaling pathway, but there may be another pathway to attenuate neuronal apoptosis in cortex of APPswe/PS1dE9double-transgenic mice.(4) These findings raise the possibility that β-asarone may be a potent therapeutic compound against Alzheimer’s disease acting through neuroprotection. |
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