Prevention Of Epileptogenesis After Brain Insults

Epilepsy is one of the most common neurological disorders characterized by recurrent and unpredictable seizures. It is estimated about 50 million people suffered from epilepsy worldwide. The currently available AEDs are mainly symptomatic, which block seizures but do not affect the underlying pathology or the progression of the disorder. Therefore, prevention of epileptogenesis has become the hot topic in epilepsy research.Epileptogenesis refers to a process in which an initial brain-damaging insult triggers a cascade of events culminating in increased seizure susceptibility and the emergence of spontaneous seizures. In recent years, numerous evidences have indicated that inflammatory reactions occur in brain after seizures induced in experimental models and in clinical cases of epilepsy. The relationship between inflammation and epilepsy is one of hot topics for epilepsy research. Previous study indicates that COX-2 inhibitor may have a role of prevention of epileptogenesis, however, whether inflammation inhibition has a potential anti-epileptogenetic effect or not remains unclear. The accumulating evidence suggests that selective COX- 2 inhibitors are associated with an increased risk of cardiovascular events, which have limited their use. Aspirin (Asp) is a non-selective COX inhibitor, and has an extensive clinical application. Our preliminary studies showed that aspirin treatment after SE reduced the frequency and duration of spontaneous recurrent seizures (SRS). Thus, this study was designed to determine whether aspirin has the function of prevention of epileptogenesis, and further explore the potential mechanism. Lithium-pilocarpine was used to induce epilepsy model of rats, we studied the effect of aspirin on the developing spontaneous recurrent seizures after SE, neuronal loss, mossy fiber spourting (MFS), aberrant neurogeneiss.1. Effects of aspirin on the developing spontaneous recurrent seizures after SELithium-pilocarpine was used to induce status epilepticus (SE). The criterion was that epileptic rats experienced Racine stage 4 or 5 seizures for 70 min. The SD rats were divided into control group , epileptic group, epileptic-0 h Asp group, epileptic-3 h Asp group, epileptic-24 h Asp group randomly and equally, according to first time treatment (0 h, 3 h, 24 h), and then aspirin (20 mg/kg , 1/d) was injected for consecutive 20 days from the day of status epilepsy (SE). Epileptic rats were video-monitored from 10 to 30 days after SE. The frequency and duration of Racine stage 4 or 5 seizures were recorded and analysised. NeuN immunostaining cells in the hippocampus were counted. The results were as followings:(1). The frequency and duration of SRS in epilepsy-aspirin group were significantly reduced compared with epilepsy-only group (P < 0.05, Mann-Whitney U test). There were no significant differences (p > 0.05) among 0 h Asp, 3 h Asp and 24 h Asp groups.(2). Treatment with aspirin alleviated SRS-induced neuronal loss in the CA3 area of the hippocampus compared with the epilepsy-only group (p < 0.05). There were no statistical difference between 3 h Asp group and 24 h Asp group (p> 0.05), but these two groups and 0 h Asp group have statistical difference (p < 0.05). Treatment with aspirin alleviated SRS-induced neuronal loss in the CA1 area of the hippocampus compared with the epilepsy-only group (p < 0.05). There were no statistical difference among of Asp groups (p > 0.05). The number of dentate gyrus neurons in each group were no statistical difference (p > 0.05).2. Effects of aspirin on mossy fiber sprouting in the hippocampus after SEThe methods of modeling Status epileptic rat and aspirin intervention are as the former. Timm histochemistry was used to observe the hippocampal dentate gyrus (DG) MFS. The study found that Aspirin administration at certain time windows can decrease MFS significantly. Compared with control group, A significant difference was found in epileptic rats (P < 0.05). 20-day aspirin treatment could decrease the MFS in hippocampal DG at 3 h and 24 h group (P < 0.05) but not at 0h group (P > 0.05). There were no statistical difference between 3 h aspirin group and 24 h aspirin group.3. Effects of aspirin on the aberrant neurogeneiss in the hippocampus after SEStatus epileptic rat model and aspirin intervention as the former, all animals were injected BrdU (i. p., 50 mg/kg) at 6 days after seizures to label newborn cells in the hippocampus. DCX staining was employed to label newborn neurons. The results were as followings:(1). After BrdU injection 28 days, most newborn neurons migrated into the granular cell layer in control group, but epilepsy-only group were associated with an aberrant migration of newborn neurons into the dentate hilus. There were statistical difference between epilepsy-aspirin group and epilepsy-only group (p < 0.05). There were no significant differences among 0 h Asp, 3 h Asp and 24 h Asp groups (p > 0.05).(2). SE induced the formation of aberrant hilar basal dendrites and hilar-ectopic newborn neurons. The number of hilar basal dendrites and the length of processes in epilepsy-aspirin group were significantly reduced compared with epilepsy-only group (P < 0.05). There were no significant differences among 0 h Asp, 3 h Asp and 24 h Asp groups (p > 0.05).(3). By using BrdU/NeuN co-labeling we observed that the ratio of neuronal differentiation of newborn cells did not reveal a statistical difference in all groups. About 80% of newborn cells differentiated into neurons (p > 0.05).In conclusion, aspirin treatment after SE reduced the frequency and duration of spontaneous recurrent seizures (SRS), which maybe owe to its function of anti-epileptogenesis in neuroprotection, suppression of MFS and aberrant neurogenesis.