Changes Of PDCD4/Autophagy Signaling Pathways And Apoptosis In Rats With Status Epilepicus

Introduction:Epilepsy is a common chronic brain disease of nervous system,which is the second largest disease after stroke.Status epilepticus(SE)is one of the most serious forms of epilepsy.The annual incidence rate of SE is(10-41)/10 000,with the mortality between 7.6% and 39%.The sustained seizure of epilepsy can not only cause neuron damage and permanent brain damage,but also cause internal environment disorder,respiratory and circulatory failure to lead to death.Studies have shown that autophagy and apoptosis are involved in neuronal damage processes in central nervous system diseases,including brain trauma,stroke,and neurodegenerative diseases,but its role in epilepsy is unclear.Autophagy is an adaptive response to various physiological stimuli,maintaining the stability of the internal environment to play a self-protection role,but excessive autophagy is harmful to the body and can cause cell death.Apoptosis is closely related to neuron death.Autophagy and apoptosis pathway share some important components,both of which are independent and interact to jointly regulate cell survival.Programmed cell death factor 4(PDCD4)is an important cause of programmed cell death and an essential event in many biological processes,such as embryonic development,normal tissue renewal,etc.Studies have shown that PDCD4 can act as upstream molecules of autophagy and apoptosis pathways in diseases such as cerebrovascular disease and central nervous system degeneration to regulate autophagy and apoptosis,thereby mitigating the effects of cell injury.And this suggests whether autophagy and apoptosis pathway can also be regulated by PDCD4 in SE,thereby alleviating the damage of brain neurons after epilepsy,but the specific mechanism needs further research and demonstration.The purpose of this study is to observe the expression changes of PDCD4,autophagy and apoptosis signal pathway in SE model of rats,and to provide the research basis for further exploring the role of PDCD4 in SE.Methods:Lithium-pilocarpine injection(i.p)was used to induce status epilepticus.The rats were randomly divided into a control group(n = 4)and a status epilepticus group.SE group Racine grade ?IV scores were further randomly divided into five subgroups,specifically,6h group(n = 4),12 h group(n = 4),24 h group(n = 4),48 h group(n = 4)and 72 h group(n = 4).qRT-PCR was used to detect the expression of mRNA levels of PDCD4,ATG5,LC3 and Beclin-1 in hippocampus of rats at different time points in control and SE groups.Western blot was used to detect the expression of the protein levels of LC3 and Beclin-1 in hippocampus of rats at different time points in control and SE groups.TUNEL staining was used to observe the apoptosis of neurons in the CA1 area of hippocampal tissue in the control group and the SE group at different time points,and the number of normal neurons and apoptotic neurons was counted.Results:(1)Behavioural observation in rats showed no significant behavioral abnormality in the control group.The rats in the epilepsy group had a generalized tonic clonic seizure after intraperitoneal injection of pilocarpine,followed by a status epilepticus.In this experiment,total 56 rats were used.The success rate of modeling was 89.2%,the mortality rate was 19.6%,and the incubation period of grade IV attack was 18.79±1.82.(2)Compared with the control group,the expression of PDCD4 mRNA in hippocampus began to increase at 12 h after SE,peaked at 48 h and decreased at 72 h,but it was still higher than that in the control group(P<0.05).(3)Compared with the control group,the expression of ATG5 mRNA in hippocampus began to increase at 12 h after SE,peaked at 48 h and decreased at 72 h,but it was still higher than that in the control group(P<0.05).(4)Compared with the control group,the expression of LC3 mRNA in hippocampusbegan to increase at 12 h after SE,peaked at 48 h and decreased at 72 h,but it was still higher than that in the control group(P<0.05).LC3 changes in protein levels were consistent with mRNA changes.The LC3II/I ratio in hippocampus after SE increased at 12 h,peaked at 48 h,and declined in 72h(P<0.05).(5)Compared with the control group,the expression of Beclin-1 mRNA in hippocampus began to increase at 12 h after SE,peaked at 48 h and decreased at 72 h,but it was still higher than that in the control group(P<0.05).Beclin-1changes in protein levels were consistent with mRNA changes.The expression of Beclin-1 protein in hippocampus after SE increased 12 h,peaked at 48 h,and decreased 72h(P<0.05).(6)Compared with the control group,the number of positive cells in hippocampus CA1 area increased 24 h after SE,reached a peak in 48 h,and began to decrease in 72 h,but it was still higher than that in control group(P<0.05).Conclusion:(1)The increased expression of ATG5?LC3 and Beclin-1 in hippocampus after status epilepticus suggests that autophagy may be involved in neuronal injury after epilepsy;(2)Apoptosis of hippocampal neurons increased after status epilepticus in rats,suggesting that apoptosis may be an important pathological change in brain injury after status epilepticus;(3)The expression level of PDCD4 in hippocampus increased after status epilepticus in rats,and the trend of PDCD4 was basically consistent with that of autophagy and apoptosis,suggesting that PDCD4 might be involved in autophagy and apoptosis of neurons after status epilepticus in rats.