| Background and Objective: Epilepsy is one of the most common and disabling neurologic diseases and is characterized by recurrent seizure activity.Approximately 65 million people worldwide suffer from epilepsy,and 30% of people with newly diagnosed epilepsy will become pharmacoresistant,eventually progressing to intractable epilepsy.Temporal lobe epilepsy(TLE)is a common form of epilepsy that is often pharmacoresistant,which results in poor prognoses for patients with TLE.Therefore,the underlying mechanisms of TLE require deeper understanding.The development of epilepsy refers to a process in which an initial brain-damaging insult triggers a cascade of molecular and neuronal network changes including neuronal death,neurogenesis,gliosis,and network reorganization that eventually generate the hyperexcitable neural circuits and lead to recurrent seizures.The hyperexcitable neural circuits may be both consequence and cause of epilepsy.The hyperexcitable neural circuits mainly consist of neurons and their synapses,and the transmission of excitatory neurotransmitter in synapses is mainly depend on excitatory postsynaptic receptors.Therefore,underlying mechanism of excitatorysynaptic transmission is crucial for further study in hyperexcitable neural circuits of TLEEndophilin A1 is primarily expressed in the central nervous system and can mediate neuronal excitability by regulating neuronal synaptic plasticity,which indicates that the protein may be involved in epilepsy.However,to date,its role in epilepsy remains unclear.To explore the role of endophilin A1 in epilepsy,we aimed to investigate the expression patterns of endophilin A1 in patients with temporal lobe epilepsy(TLE)and in a pentylenetetrazole(PTZ)-kindled epileptic mouse model,and to explore the mechanisms of endophilin A1 in epilepsy by conduct behavioral,electrophysiological and other analyses after lentivirus-mediated knockdown of endophilin A1 in the hippocampus of epileptic mice.Methods: In this study,by using western blot,immunohistochemistry,immunofluorescence labeling,we explored the expression and distribution of endophilin A1 in temproal cortex of TLE patients,hippocampus and temporal cortex of epileptic mice.Recombinant lentivirus was also used to knockdown the expression of endophilin A1 in order to explore the role of endophilin A1 in epileptogenesis.Further studies about the mechanism of endophilin A1 in epilepsy were conducted by recombinant lentivirus transduction,western blot,co-immunoprecipitation,immunofluorescence labeling,whole-cell patch-clamp recordings and other technical means.Results: This study found that endophilin A1 was expressed in theneuronal cytomembrane and cytoplasm of the temporal cortex tissue of human and hippocampus and adjacent temporal cortex of mice.The expression of endophilin A1 was significantly up-regulated in the temporal neocortex of TLE patients and in the hippocampus and adjacent temporal cortex of the PTZ-kindled epileptic mouse model.This suggests that endophilin A1 may be related to the occurrence and process of epilepsy.Behavioral analyses indicated that knockdown of endophilin A1 in the mouse hippocampus increased the latency of the first seizure and reduced the frequency and duration of seizure activity,which suggest that endophilin A1 may promote seizure susceptibility.Whole-cell patch-clamp recordings of pyramidal neurons in the hippocampal CA3 area indicated that knockdown of endophilin A1 in the mouse hippocampus resulted in a reduced frequency of action potentials and decreased amplitudes of miniature excitatory postsynaptic currents(mEPSCs)and evoked AMPA-dependent EPSCs.Moreover,western blotting analysis showed that the surface expression of the AMPAR GluR2 subunit was also decreased after endophilin A1 knockdown,and co-immunoprecipitation indicated an association between endophilin A1 and AMPAR GluR2 in the mouse hippocampus.Further,when AMPARs were activated by CX546,the antiepileptic function of endophilin A1 knockdown was decreased.These results indicate that endophilin A1 may regulate excitatory synaptic transmission and neuronal excitability byregulating the cell surface AMPAR GluR2 expression,thereby participating in the epileptogenesis.Conclusion: Our data showed that endophilin A1 was upregulated in epileptic tissue and promote excitatory synaptic transmission,neuronal excitability and the occurrence and process of epilepsy via cell surface expression of AMPAR GluR2,which suggests that endophilin A1 could be a potential therapeutic target for the treatment of epilepsy and establishes the foundation for further study of epilepsy... |
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