Pitavastatin Induces Neuroprotection Through BDNF-TrkB Signalling Pathway In Culture Cerebral Neuron After Oxygen-glucose Deprivation

BackgroundCerebral ischemia,produced by interrupting blood flow to the brain,would cause serious neurofunction deficit.In 2013,a nationally representative door-to-door survey was conducted in 155 urban and rural centers in 31 provinces in China,totaling 480 687 adults aged ?20years.The survey showed that the age-standardized prevalence,incidence,and mortality rates were 1114.8/100 000 people,246.8 and 114.8/100 000 person-years,respectively.It's the main reason leading to morbidity and mortality in our country,and brings not only physical but also mental suffering to the patients,and heavy financial burden to the family and community as well.Ischemia cause cerebral damage,and when reperfusion occur,inflammatory response and Reactive Oxygen Species would cause further worsening of ischemic brain tissue.There is a growing need for neuroprotect agent to protect the ischemic reperfusion injury(IR).Statins,a 3-hydroxy 3-methylglutaryl coenzyme A(HMG-CoA)reductase inhibitor,has been commonly applied to lower plasma cholesterol levels,specifically low density lipoprotein(LDL)-associated cholesterols,And it is the first line pharmacological treatment in all international guidelines for the prevention of cardiovascular and brain ischemia disease.Researches found that statins have pleiotropic effect besides cholesterol lowering,including immunomodulatory effect,neuroprotective effect,and modulation of oxidative and nitrosative stress.Pitavastatin is the third statin.It is safe and has rather limited side effects for that it is poorly metabolized by cytochrome P450(CYP)2C9.compaired with other statin,pitatvastatin doesn't increase the risk of glucose metabolism.BDNF(brain-derived neurotrophic factor)which belongs to the neutrophin family of growth factors is highly expressed in the central nervous system.It is crucial for the survival,differentiation and plasticity of neurons.BDNF is synthesized in the endoplasmic reticulum as a precursor protein(proBDNF)of 32 kDa,which is cleaved intracellularly by furin or extracellularly by plasmin or matrix metalloprotease-7 to produce mature form(mBDNF).Mature BDNF is believed to induce axonal branching and alters the structure and function of dendritic extremities.These biological effects of BDNF are realized via binding to the tropomysin-related kinase B(TrkB)receptor.The definite mechanism of statins' neuroprotective effect hasn't been clarified clearly.The aims of our study was to investigate the neuroprotective effect of PTV and seek the potential molecular mechanism with BDNF-TrkB signal pathway via mimicking cerebral ischemia.Objective:To investigate whether pitavastatin protect the cortical neurons from hypoxia/reoxygenation injury,and explore the proper neuroprotection concentration.To explore the potential molecular mechanism of pitavastatin's neuroprotive effect with the BNDF-TrkB signal pathway.Methods:We first culture primary cortical neurons,and then divide them to following groups randomly: the control group,the pitavastatin group,the OGD group,the OGD + pitavastatin group.The neurons were treated with pitavastatin for 48 hours and OGD for 3 hours.The concentration of pitavastatin was set as 1?mol/L,15?mol/L,30?mol/L.We investigated the survival neurons with MTT;The neuron morphology were observed with immunofluorescence and the dendrites of the neuron were counted;the dimmer-BDNF,the homo-BDNF and TrkB was detected with western blot method analysis.Results:1.Compared with the control group,the neuron activity in the OGD group were decreased significantly(P<0.05);The neuron activity in PTV treatment groups showing no significant differences to the control group,and there wasn't statistical difference among1?mol/L,15?mol/L,30?mol/L PTV groups(P>0.05);Compared with OGD group,theneuron activity in the OGD + 1?mol/L PTV and OGD +15?mol/L PTV increased significantly(P<0.05);there was no statistical difference between the OGD + 1?mol/L PTV and the OGD +15?mol/L PTV group(P>0.05);The neuron activity in the OGD + 1?mol/L PTV and OGD +15?mol/L PTV was higher than the OGD + 30?mol/L PTV;The neuron activity in OGD + 30?mol/LPTVhas no statistical difference to the OGD group(P>0.05).2.Compared with control group,the neuron dendrite number in the OGD group reduce significantly and the length of dendrite got shorter(P<0.05);the neuron dendrite number in the PTV treatment group had no statistic difference(P>0.05)to the control group;Compared with OGD group,the neuron dendrite number in the OGD+1?mol/L PTV and OGD+15?mol/L PTV increased significantly(P<0.05),while the length of dendrite shows no statistic difference(P>0.05);The neuron dendrite number and the length of dendrite in the OGD+30?mol/LPTVtreatment group shows no statistic difference to the OGD group.3.Compared with the control group,the expression of protein dimmer-BDNF,homo-BDNF,TrkB decreased significantly(P<0.05).Compared with control group,the expression of protein dimmer-mBDNF,homo-mBDNF,TrkB increased significantly in the1?mol/L,15?mol/L PTV treatment group(P<0.05);Compared with OGD group,the expression of protein dimmer-mBDNF,homo-mBDNF,TrkB increased significantly in the OGD+1?mol/LPTVgroup,OGD+15?mol/LPTVgroup(P<0.05).Conclusions:1.Hypoxia/reoxygenation has damage to the cortical neurons activity.2.PTV has no protective effect to the normal cortical neuron.PTV in proper concentration would protect cortical neuron from hypoxia/reoxygenation damage;The neuroprotective effect of PTVwas concentration-dependent.3.Pitavastatin promote the regeneration of dendrite injured by hypoxia/reoxygenation,and the neuroprotective effect of PTVwas concentration-dependent.4.Pitavastatin may induce neuroprotective effect through BDNF-TrkB pathway.