The Role of Decreased Levels of Neuronal Autophagy in Increased Susceptibility to Post-traumatic Epilepsy

Post-traumatic epilepsy (PTE) caused by mild TBI (mild traumatic brain injury, mTBI) has a high incidence and poor prognosis, but its mechanisms are unclear. Herein, we investigated the role of reduced levels of neuronal autophagy during the latency period in the increased susceptibility to PTE. In the study, a gentle whole-body mechanical trauma rat model was prepared using Noble-Collip drums, and the extent of injury was observed by cranial CT and HE staining of hippocampal tissue. The incidence of epilepsy and its seizure form were observed 7-90 days after mTBI, and electroencephalography (EEG) was recorded during seizures in rats. Subcortical injection of non-epileptogenic dose of ferrous chloride (FeCl₂) was used to observe the changes of PTE incidence after mTBI. Western blot and Real-time PCR were used to detect the level of autophagy in hippocampal cells at different time points during the latency period of PTE, and its incidence was observed after up-regulation of autophagy after administration of autophagy agonist-rapamycin. The results showed that mTBI was prepared by Noble-Collip drum, which could better simulate the clinical mTBI process. There was no intracerebral hemorrhage and necrosis in rats, no early-onset seizures, and the incidence of PTE after mTBI was 26.7%. The incidence of PTE was 56.7% in rats injected cortically with FeCl₂ at a dose lower than the epileptogenic dose 48 h after mTBI, and the difference was significant compared with no FeCl₂ injection, suggesting an increased susceptibility to PTE after mTBI. Further study of neuronal autophagy during PTE latency revealed that autophagy levels were reduced, and the incidence of PTE was significantly reduced after administration of rapamycin to upregulate autophagy. Taken together, the decreased level of neuronal autophagy during the latency period may be a possible mechanism for the increased susceptibility to PTE after mTBI.