Alternations Of Autophagy And Apoptosis In Mice With Status Epilepticus

Epilepsy is a chronic,common and sometimes devastating neurological disorder,characterized by widespread neuronal loss followed by neurogenesis,gliosis,mossy fiber sprouting and changes in synaptic transmission in the hippocampus.Apoptotic cell death is a common neuropathological finding in patients with temporal lobe epilepsy and laboratory animal models with hippocampal neuron loss.and autophagy has been proved to be cytoprotectional,but its role in epileptogenesis is unclear and controversial.To investigate the precise roles of these processes in epilepsy-induced neuronal loss,this study detected the time-dependent changes of Akt/mTOR pathway,autophagy and apoptosis in mice that had already developed status epilepticus in a pilocarpine model by western blotting.Material and method:Adult(6-8week old)male C57BL/6 mice were randomly divided into a control group(n = 10)and a status epilepticus group.Mice with successful status epilepticus were randomly divided into six sub-groups,specifically,0 h group(n = 6),4 h group(n =6),8 h group(n = 6),12 h group(n = 6),16 h group(n = 6)and 24 group(n = 6).Status epilepticus was induced by LiCl-pilocarpine intraperitoneal injection.Briefly,mice were injected with LiCl(127mg/kg,i.p.)18-24 h prior to pilocarpine(30mg/kg,i.p.).Atropine was adminseted 30 min before pilocarpine to minimize peripheral side effects.The control rats were administered an equal volume of saline.Behavioral seizures were graded accordingto the Racine scale.Status epilepticus was terminated with diazepam(7.5mg/kg,i.p.)60 min after SE onset.Mice were sacrificed at various time points following the onsetof SE for the western blot analysis.Results:(1)SE induced by LiCl-pilocarpine:after the administration of pilocarpine,36 mice developed SE with morbidity of 72%.Latency to the first seizure(at least stage IV)or to SE after pilocarpine administration was 6.97±4.04min;Single seizure duration was 5.45±4.16min;The duration of SE was 33.82±19.07 min.(2)The Akt/mTOR pathway was activated in mice with SE: a large increase in ratio of p-Akt(Thr308)/Akt 4h after SE onset compared with the control group(P<0.05).A large increase in the ratio of p-mTOR(Ser2448)/mTOR fom 0-4h after SE onset compared with the control group(P<0.05)(3)Autophagy was impared in mice with SE:there was no LC3 II but LC3 I either in control group or in SE group.The expression of Beclin 1 was slight increased after pilocarpine injection without no statistic difference between control group and in SE group.(4)The apoptic pathway was activated in mice with SE: the levels of the Bcl-2 protein were significantly decreased from 8-24 h post-SE onset compared with 0h group.The levels of the Bim protein were significantly increased at 24 h post-SE onset compared with the control group.Conclusions:(1)The Akt/mTOR pathway was activated in mice with SE;(2)Autophagy was impared in mice with SE;(3)The apoptic pathway was activated in mice with SE;(4)Impared autophagy was unable to restrain the abnormal activation of apoptosis signaling pathways in hippocampal neuron death,both impaired autophagy activity and abnormal activation of apoptosis contributed to the process of hippocampal neuron loss.