Aniracetam Attenuates Scopolamine-induced Cognitive Impairment And Increases Synaptic Plasticity

Objectives: As the most common forms of senile dementia,Alzheimer's disease(Alzheimer disease AD)is a neurodegenerative disease related to age,with the clinical features of insidious onset,progressive memory and cognitive dysfunction,accompanied by personality,mental disorders.While the pathologically characteristics is deposition of amyloid-beta(A?)plaques extracellularly,neurofibrillary tangles(NFTs)intracellularly,and the decrease of cholinergic neurons and the number of synapses.So far,the pathogenesis of AD is still not very clear,the medical profession at domestic and abroad are mainly the following: the theory of cholinergic nerve damage,the theory of mitochondrial damage,the theory of oxidative stress,the theory of gene mutation and genetic,however there is no theory to elucidate its pathogenesis.Scopolamine is a blocker of muscarinic acetylcholine receptor and blocks the excitatory effects of acetylcholine on the muscarinic receptors in the cerebral cortex and hippocampus.The result is producing an inhibitory effect on memory acquisition and lead to dementia.It has been used in the assessment of neurotrophic drugs.Previous studies have confirmed intraperitoneal administration of scopolamine with 3mg/Kg can cause animal memory dysfunction.Animal memory impairment model induced by scopolamine has the advantages of simple,economical and convenient,and is often used in the preliminary screening of anti-AD active compounds.As a cyclized derivative of ?-aminobutyric acid,aniracetam is a brain metabolism enhancer.It was accepted that aniracetam seems to exert certain long-term effects on severe clinical depression.What's more,it can reduce anxiety in mice.The main mechanism of aniracetam may be the regulating of AMPA receptorand acetylcholine system,but it has not yet seen any application of aniracetam on scopolamine induced dementia model.In the present study,we usescopolamine-induced dementia as AD model to explore the glutamate(GluR1)receptor,synaptic plasticity protein expression,and whether aniracetam can activate the glutamate receptor phosphorylation and increase the expression of synapses to improve the cognitive function of AD mice.Methods:96 male BALB/c mice of SPF grade were purchased from Beijing Vital River Laboratory Animal Technology Co and were housed in the Animal Research Center of Hebei Provincial People Hospital.Managed by the animal center breeder,with standard rat grain and pure drinking water.The mice were randomly divided into 6 groups: vehicle group(vehicle saline 3mg /kg,vehicle group),model group(SCO 3mg/kg,SCO group),low dose group(SCO 3mg/kg + aniracetam 40mg/kg L-A group),medium dose group(SCO3mg/kg + aniracetam 80 mg / kg,M-A group),high dose group(SCO 3mg/kg+ aniracetam 160mg/kg,H-A group),Huperzine A group(SCO 3mg/kg +huperzine A 0.15mg/kg,Huper-A group),each group has 16 mice.SCO subcutaneous injection once a day,continuous administration of 60 days,aniracetam and huperzine A in the 50 th day irrigation Stomach administration,once a day,continuous administration of 10 days.The expression of ERK1/2,p-ERK1/2,GluR1,p-GluR1Ser845 and PSD-95,SYN were detected by Western blot analysis.RT-qPCR technique was used to determine the mRNA expression of ERK1/2,GluR1,PSD-95 and SYN.The number of positive cells of ERK1/2,PSD-95 and SYN in hippocampus was determined by immunohistochemistry.The acetylcholinesterase activity was measured by dedicated kit.Results:1 Aniracetam Treatment Rescued Cognitive impairment in AD Mouse induced by scopolamineThere was no statistically significant difference in the total exploration times between the six groups.Compared with vehicle group,the RI of SCO group was significantly decreased(P<0.01),scopolamine significantly reduced the cognitive function of mice..Compared with SCO group,the RI ofM-A and H-A group was significantly increased(P<0.05,P<0.01);aniracetam could improve the cognitive function of AD mouse induced by scopolamine.2 Aniracetam Treatment exert effect on synpatic proteins2.1 Aniracetam Treatment Stimulate ERK1/2 Phosphorylation in AD Mouse Hippocampus induced by scopolamineCompared with vehicle group,the expression of p-ERK1/2 and p-GluR1 protein in hippocampus of SCO group was significantly decreased(P<0.01).Compared with SCO group,the levels of p-ERK1/2 protein in hippocampus of M-A and H-A groups were significantly increased(P<0.05,P<0.01),the expression of p-ERK1/2 in the positive control group was also significantly higher than that in the control group(P<0.01)2.2 Aniracetam Treatment Stimulate and GluR1 Phosphorylation in AD Mouse Hippocampus induced by scopolamineCompared with vehicle group,the expression of p-GluR1 protein in hippocampus of SCO group was significantly decreased(P<0.01).Compared with SCO group,the levels of p-GluR1 protein in hippocampus of H-A group were significantly increased(P<0.01),the expression of p-GluR1 in the positive control group was also significantly higher than that in the control group(P<0.01)2.3 Aniracetam Treatment Restored Synaptic Protein Alteration in AD Mouse Hippocampus induced by scopolamineCompared with vehicle group,the expression of PSD-95 and SYN protein in hippocampus of SCO group was significantly decreased(P<0.01,P<0.01).Compared with SCO group,the levels of PSD-95 and SYN were significantly increased in L-A group(P<0.05,P<0.01).The expression of PSD-95 and SYN protein in positive control group was significantly higher than that in SCO group(P<0.01,P<0.01).3 Aniracetam Treatment upregulated the gene expression of ERK1/2,GluR1,SYN,PSD-95 in AD mouse hippocampus induced by scopolamineCompared with the vehicle group,the expression of ERK1/2,GluR1,SYN,PSD-95 gene in hippocampus of SCO group was significantly decreased(P<0.01,P<0.01).Compared with SCO group,the levels of hippocampal genes in M-A and H-A groups were significantly increased(P<0.01),and the expression of corresponding protein in positive control protein was significantly increased(P<0.01).4 Aniracetam Treatment didn't Increase the Activity of Acetylcholinesterase in AD Mouse Hippocamus induced by scopolamineResults showed that the AChE activities in hippocampal tissues were increased by scopolamine injection compared with the vehicle group(P<0.05),while aniracetam treatment at any of dose substantially inhibited the hyper-activation of AChE activity.But the treatment didn't show any significant difference(P>0.05).As a positive control,donepezil(5 mg/kg)pretreatment also reversed the scopolamine-induced increases in ACh E activities in the hippocampus(P<0.05).Conclusion:1 aniracetam can improve the ability of learning and memory in AD mouse model caused by scopolamine mice.2 aniracetam can improve the learning and memory ability in AD mouse model caused by increasing the phosphorylation of glutamate receptors and the expression of synaptic-associated proteins.