The Role Of MiR-34a In Rat Hippocampal Neuron Apoptosis Following Status Epilepticus

ObjectiveTo study the expressional change of miR-34a in rat hippocampus following status epilepticus (SE). Through intervention of expressional level of miR-34a, this research was also aimed to explore the role of miR-34a and its mechanism in neuronal apoptosis in rats following SE.Method1. SE Model:6-8week, healthy male SD rats were randomly divided into the negative control group (Normal, N group), the epilepsy group (epilepsy, Ep group), the intervention group (Antagomir, A group) and the intervention control group (Antagomir-control, C group). Then the lithium chloride-pilocarpine SE model was established, A and C groups.4-6hours after models set, Antagomir and Antagomir-control were injected into rats'lateral ventricle to intervene miR-34a level in A and C groups by animal brain stereotactic skills. Then corresponding indicators in1day (24hours, Acute phase) and7days (Quiescent) after SE were observed.2. The experimental rats EEG for physiological state, SE, interictal state and spontaneous onset state were recorded to verify that the models were set successfully. 3. Quantitative real-time PCR(qRT-PCR) detection was performed to study the miR-34a expression level in rats after SE.4. Western blot and Immunohistochemical detection were used to detect the expression level of caspase-3protein.5. TUNEL (Terminal deoxynucleotidyl transferase-mediated dUTP nick-end-labeling) was used to detect hippocampal neuronal apoptosis in experimental rats.6. Nissl staining was exploited to detect hippocampal neuronal loss and retention in experimental rats.Result1. Based on animal behavior and EEG results, a successful rate of89.7%for SE rats modules was made in A and C groups. After modules set and intervention, there were69.17%rats (Ep, A and C groups) alive. Meanwhile the cause of death mainly included restored ability, anesthesia, surgical trauma and other factors.2. qRT-PCR results showed that the expression change of miR-34a at acute phase and quiescent were in consistent trend. Ep group's miR-34a level was significantly higher than N group's, whereas A group's miR-34a level was significantly lower than C group's.3. Western blot results showed that expression of caspase-3protein at acute phase and quiescent were in consistent trend. The caspase-3 protein level in Ep group was significantly higher than N group's, whereas A group's caspase-3protein level was significantly lower than C group's, which was consistent with the results of qRT-PCR.4. Immunohistochemical results showed that expression of caspase-3protein at acute phase and quiescent were in consistent trend. The expression level of caspase-3protein in Ep group was significantly higher than N group's, whereas A group's caspase-3protein level was significantly lower than C group, which was consistent with qRT-PCR and Western blot results.5. TUNEL results showed the apoptotic neurons at acute phase and quiescent were in consistent trend. The hippocampal neuron apoptosis of Ep group was significantly higher than that of N group, whereas the hippocampal apoptotic neurons of A group was significantly lower than its counterpart in C group.6. Nissl staining results showed the survival and loss of neurons at acute phase and quiescent were in consistent trend. The loss of hippocampal neurons in Ep group was significantly higher than in N group, wheras survival of hippocampus neurons in Ep group was significantly lower than that in N group. The loss of rat hippocampal neurons in A group was significantly lower than that in C group, while survival of hippocampal neurons in A group was significantly higher than that in C group. ConclusionAfter mice SE (at acute phase and quiescent), miR-34a in hippocampal neuron could increase the expression of caspase-3, activate the downstream pathway of apoptosis, and lead to hippocampal neuron loss.