MiR-132 Regulates The Expression Of Synaptic Proteins In APP/PS1 Transgenic Mice Through C1q

Objectives: Alzheimer’s disease(AD)is a neurodegenerative disease characterized by progressive cognitive dysfunction and behavioral impairment in the aging brain.The main manifestations are deteriorating cognitive and memory functions,which are clinically characterized by dementia such as memory impairment,executive dysfunction,personality and behavior changes.According to their family history,they can be divided into Sporadic Alzheimer’s disease(SAD)and Familial Alzheimer’s disease(FAD),in which sporadic Alzheimer’s disease accounts for 99% of the total number.The impact is increasing globally and is expected to affect nearly one in every 85 people worldwide by 2050.Pathological changes include amyloid plaque,neurofibrillary tangles,and neuronal reduction.Investigation found that the main risk factors and pathogenesis of AD include age,type II diabetes,apolipoprotein,E-4 gene theory,alkalinity toxicity theory,calcium metabolism disorder theory,aluminum poisoning theory,free radical damage theory etc.Synapses are the main structure of signals transmission between neurons.and the changes of synaptic are closely related to learning and memory.Synaptic plasticity is thought to be the key to early development of neuronal circuits,and recent evidence suggests that impaired synaptic plasticity leads to several major neuropsychiatric disorders.Although the etiology of AD has not been clarified,decreased synaptic density,impaired synaptic transmission and synaptic plasticity are the pathological basis of cognitive dysfunction and the main signs of AD.Classical complement cascade is a component of the innate immune system,and the innate protein of the classical complement pathway is C1q.During development,C1q and C3 are located at synapses and mediate synaptic clearance by phagocytic microglia.In healthy brains,C1q promotes the activation of C3,which makes the subsets of synapses clearable,while in aging brains,this process is significantly down-regulated.Therefore,inhibition of C1q can reduce synaptic loss,but the specific mechanism has not been clarified.Current studies have found that the expression of miR-132 in AD is significantly down-regulated,while the expression of C1q in AD is significantly increased,and both of them have influence on the expression of synaptic proteins.Therefore,this study used behavioral,Western blot,immunofluorescence,Real-time q PCR and other experimental methods to explore whether miR-132 regulates the expression of pre-frontal synaptic-related proteins in APP/PS1 transgenic mice through C1q,thereby improving the learning of APP/PS1 transgenic mice,providing a new theoretical basis for the prevention and research of Alzheimer’s disease.Methods: Twelve adults male C57BL/6 mice and thirty-six APP/PS1 transgenic mice were used.36 APP/PS1 mice were randomly divided into three groups with 12 mice in each group,namely AD group,AD+C1INH group,AD+ miR-132 overexpression group,and C57 mice as the normal control group.The experimental animals were raised in the same experiment environment for a week,room temperature 22 ℃,with suitable humidity.The C1 INH and miR-132 overexpression were injected into the lateral ventricle(right side),and 3μl.Seven days later,behavioral tests were performed after all anima models,and then mouse brain were taken.Western blot,immunofluorescence,Real-time q PCR and other experimental methods were used to observe the expression changes of prefrontal synaptic related proteins.Results: 1.Morris water maze behavior test results : Positioning cruise experiment showed that the average latency of the AD group was longer than that of the normal control group(P<0.05).The average latency of the AD+C1INH and AD+ miR-132 overexpression groups was significantly shorter than that of the AD group.Space exploration experiments showed that the number of crossing the platform was less in the AD group compared with the normal control group(P<0.05),and the number of crossing the platform was significantly increased in the AD+C1INH and AD+ mir-132 overexpression groups.It showed that the spatial learning behavior and cognitive ability of mice were significantly improved.However,there was no significant difference between the mice in the normal group(P>0.05).2.Western blot and Immunofluorescence results: The expression of PSD95 and p-Synapsin in the Prefrontal cortex of AD group is significant decrease(P<0.05).However,we found that either miR-132 overexpression or C1 INH administration resulted in a significant increase in the expression of PSD95 and p-Synapsin in the Prefrontal cortex(P<0.05).There was no significant difference between the mice in the normal group(P>0.05).3.Real-time q PCR results: the expression of C1q in AD+ mir-132 group was significant decreased compared with that in AD+ mir-132 group.On the contrary,the expression level of AD+ mir-132 increased significant(P<0.05).Conclusion: 1.miR-132 and C1 INH may effectively improve and delay the occurrence of Alzheimer’s disease.2.miR-132 may affect the expression of prefrontal synaptic protein in AD mice by regulating C1q.