Expression Alteration Of Rnd1 MRNA And Protein In Rat Hippocampus Of Temporal Lobe Epilepsy

ObjectiveOur aim is to investigate the mRNA and protein expression alterations of Rnd1 in hippocampi of LiCl-pilocarpine induced epileptic rats, as to further explore the mechanisms of mossy fiber sprouting and epileptogenesis.Method124 healthy male Sprauge-Dewly adult rats were randomized into model group and control group, the former of which were further randomized into post-status 8h, 1d, 3d, 7d, 15d, 30d and 60d group. LiCl and pilocarpine injection were given to induce status epilepticus. Once SE was successfully induced, the animals were monitored every day for the behavior and spontaneous seizure observation. In addition, EEG was performed on 8h, 7d, and 60d post status to confirm the animal model preparation.Both revert transcript polymerase chain reaction and immunohistochemical staining were performed in each group to identify the expression alterations of Rnd1 mRNA and protein in hippocampus hilus, CA1 and CA3 region.Result1. In the model group, rats which exhibited seizures above Raccine grade IV for over 1 min were considered in status epilepticus. 10% chloral hydrate was injected intraperitoneally to terminate the seizure. There were a latency period of 18～28 days between the initial acute stage and the following chronic stage in which rats experienced recurrent spontaneous seizures. The SE induction rate was 88.4%, while the percentage of rats that developed recurrent spontaneous seizures was 68.8%, though 19.6% of the rats died during model preparation. EEG results showed abnormally epileptiform discharges in both acute and chronic stages.2. RT-PCR is performed to detect the Rnd1 mRNA expression change. The outcome is normalized and expressed as a Rnd1/β-actin ratio. The experiment revealed that Rnd1 mRNA expression upregulation occurred with 8h post status and maximized around 1d post status, which returned to normal level until 7d post status.3. Immunochemical staining revealed anti-Rnd1 positive cells located mainly in hilus of dentate gyrus, as well as in CA1 region. Rnd1 protein upregulation started as early as 8 h post status, and maximized around 3 d post status. Though the protein expression turned down since 7 d post expression, it still remained above the control level and the upregulation continued in chronic stage. What's more, Rnd1 protein upregulation occurred again in CA1 region of hippocampus during chronic stage.ConclusionHippocampal Rnd1 upregulation in acute stage may participate in the initiation of mossy fiber sprouting in temporal lobe epilepsy.