The Effect Of Icariin On The Expression Of GSK-3β In The AD Cell Models And Its Possible Mechanism

Background and Objects:Alzheimer’s disease (AD) is a chronic neurodegenerative disease in the elderly. The main pathological features of AD is (3-amyloid (A(3) with neurotoxicity produced in the brain, which causes degeneration and loss of brain neuron cells through a series of complex molecular pathological mechanism, eventually leads to cognitive impairment. The abnormal deposition of Aβ in the brain is the initial factor of memory impairmentin AD patients. Glycogen synthase kinase3(3(GSK-3β) is a multifunctional serine/threonine kinase widely exists in eukaryotic cells. It is a key regulatory enzyme of glycogen synthesis and is one of the few protein kinase which inactivate through phosphorylation. GSK-3β participates in multiple cellular signal transduction pathways and is one of downstream molecules in PI3K/Akt pathway. The excessive activation of GSK-3β accelerates the Alzheimer’s disease-like pathological process by promoting Aβ generated by the degradation of amyloid precursor protein, accelerating abnormal hyperphosphorylation of tau protein (a nerve cytoskeletal protein), aggravating the neuronal degeneration, and interfering the normal synaptic plasticity. So, the research of regulatory mechanism of GSK-3β is crucial to the treatment of AD. The inhibition of excessive activity of GSK-3β has become the new target of drugs to AD.Icariin (ICA) is a kind of flavonoid of Berberidaceae Epimedium plants. 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. This research aimed to investigate the survival rate and the expression of GSK-3β of AD cell model influenced by ICA, reveal the partly pathogenesis of AD and the mechanism of action of ICA, and provide theoretical and experimental basis for the clinical application and development of new drugs of AD.Methods:AD cell models were divided into5groups, including normal control group, A(3group, ICA+Aβ group, Aβ+LY group, and ICA+Aβ+LY group (LY is the classical inhibitor of PI3K/Akt). The survival rate of each cell group was detected by MTT. The expressions of Akt, p-Akt, GSK-3β, and p-GSK-3p in each cell group were detected by Western-Blot.Results:(1) Compared with control group, The survival rates of PC12cells incubated by Aβ declined significantly(P<0.01); Compared with models group,The cell survival rates of ICA group increased significantly (P<0.01); Compared with ICA group, the cell survival rate of ICA+LY group is declined, the difference is of statistical meaning(P<0.05).(2) Compared with the control group, the level of p-GSK-3β and p-Akt of the model group declined significantly (P<0.05).Compared with the control group, the level of p-GSK-3p and Akt of ICA group increased significantly (P<0.05). Compared with the ICA group, the level of p-GSK-3p and Akt of ICA+LY group declined significantly(P<0.05).Conclusions:(1) To use Aβ25-35to induce PC12cells, Cell viability will decrease remarkably. ICA pretreatment can significantly improve cell viability.(2) 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) A(325-35can decrease P-Akt and p-GSK-3β of 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 P-Akt and p-GSK-3p expression through the PI3K/Akt signal pathway.