Effect Of Icariin On Expressions Of CREB And BDNF In The AD Cell Model And Its Potential Mechanism

Objective:Alzheimer’s disease is fatal neurodegenerative diseases caused by multiple factors on a progressive course. Its clinical performances are gradual deterioration of cognitive ability and memory capacity, progressive loss of daily living ability, and accompanied by a variety of neuropsychiatric symptoms and behavior disorders. Senile plaques (SPs) and neurofibrillary tangles (NFTs) are considered to be the key pathological features of AD. Most scholars believe that β-amyloid protein (β-amyloid,A(3) deposition is an important factor in the pathogenesis of AD, which plays a key role in inducing AD. A(3has neurotoxicity. To adopt Aβ25-35induce injury in PC12cells to establish a cellular model of AD has been used for many experiments in vitro studies. As the principal active ingredients of epimedium belonging to Berberidaceae, Icariin (Icaritin ICA) had multiple pharmacological effects. In recent years, more and more researches has focused on pharmacological actions and molecular mechanisms of icariin in central nervous system, including anti-dementia, anti-aging, anti-ischemic brain injuries, anti-depression, et al. cAMP response sequence binding protein (CREB) is an important nuclear transcription factor to regulate gene transcription of cyclic adenosine monophosphate response unit (CRE). It has an adjustment function in neuron regeneration, synapse formation, learning and memory. Brain-derived neurotrophic factor (BDNF) is an important factor in the components of neurotrophic factors (NT). It has a protective effect to peripheral and central nervous system, which could not only promote neuronal survival, growth and differentiation, but also play an important role in the accommodation of synaptic transmission and synaptic plasticity. In vitro experiments found that if it was given neuron sub-toxic doses of Aβ1-42, CREB signal transduction pathway would be obstructed, BDNF levels fell and further lead to synaptic dysfunction and neuronal degeneration. This study discusses whether ICA has a neuroprotective effect to induced damage in PC12cells towards Aβ25-35with the model of AD. It seeks to the effect of Icariion on expressions of CREB and BDNF in the AD cell model.Methods:1.Cell Culture:PC12cells were cultured in high glucose DMEM medium containing10%fetal bovine serum,100U/ml streptomycin and100U/ml penicill in the incubator at37℃with5%CO2. Liquid for a2day, Drug intervention and all the indexes have tested in logarithmic growth phase cells.2. MTT assay:Experimental group division:control group, Aβ group, ICA group, LY group, and LY+ICA group. Except control group, the concentration of Aβ in rest four groups is20μmol/L; ICA group:add ICA to incubate for1hour, and then add Ap, the ICA is20μmol/L.; LY294002concentration in LY group is50μmol/L; In LY+ICA group, first add LY294002concentration50μmol/for1hour, and then add ICA and Aβ to make concentration become20μmol/L3.Western blot detection:the experimental division is the same as (2).TO detect protein expressions of P-CREB(Serl33)/CREB, BDNF, P-Akt(Ser473)/Akt.Results:1. Compared with the Control group, PC12cell survivol decreased significantly in Aβ group, the difference is obvious(P<0.01); Compared with Aβ group, the improvement of cell survival of ICA group is obvious(P<0.01);Compared with ICA group, PC12cell viability decreased in ICA+LY group, the difference is of statistical meaning(P<0.05);2. Compared with the Control group, Aβ processing of P-CREB, BDNF, P-Akt protein expression is decreased. The difference is of statistical meaning (P<0.05); ICA groups can significantly increase the P-CREB, BDNF and P-Akt protein expression (P<0.05) comparing with Aβ group; Compared with the ICA group, P-CREB, BDNF, P-Akt protein expression pretreated by adding LY29400250μM is clearly inhibited (P<0.05)；Conclusion:1. To use Aβ25-35to induce PC12cells, Cell viability will decrease remarkably. ICA pretreatment can significantly improve cell viability2. After the effect of the inhibitor LY294002through PI3K/Akt signal pathway, the impact of ICA to improve PC12cell viability is conspicuously compressed. ICA may play a protective role through PI3K/Akt signal pathway.3. Aβ25-35can decrease P-CREB, BDNF, P-Akt protein levels in PC12cells;ICA pretreatment can significantly increase the above protein expression to protect cells.4. After the effect of the inhibitor LY294002through PI3K/Akt signal pathway, the impact of ICA to improve the above protein expression is clearly inhibited. The protective effect of ICA on PC12cells may relate with the increase of CREB, BDNF expression by the PI3K/Akt pathway.