Expression Of Activin βA In The Mouse Hippocampus After Seizures Induced By Pilocarpine And The Protective Effect Of Recombinant Human Activin A

Epilepsy is a common neurological disease which characterized by chronic and spontaneous recurrent seizures.The cause and pathogenesis of epilepsy are very complex,and no radical drugs exist until now.Animal experiments have demonstrated that prolonged and recurrent seizure activity can result in a series of pathological changes including hippocampal neuronal cell death ,reactive gliosis and mossy fiber sprouting,which may be a basis for chronic and recurrent seizures of epilepsy.It has been proved that some cytokines and growth factors facilitate the genesis of these pathological changes,and some have an effect of anticonvlusion and neuroprotection.These results suggested that cytokines and growth factors may have a important role in the mechanisms underlying seizure-induced neuropathological changes and hopefully contribute to future therapeutic interventions.Activin is a member of the transforming growth factor-β superfamily.Activin is classified into activin A,activin B and activin AB,which are formed by two β-subunits of βA-βA,βB-βB and βA-βB respectively.Recent works indicated thatβA mRNA of activn was strikingly upregulated in the hippocampi following hypoxic-ischemic injury,focal mechanical brain injury and kaninc acid-induced excitoxic brain injury,butβB mRNA of activin showed no detectable changes. It was also found that exogenous application of activin A can protect neurons both in vitro and in vivo against injuries.Very recent study showed that induction of activin A is an essential step in the signaling cascade of basic fibroblast growth factor required for neuroprotection.Therefore,it is possible that activin A may play a critical role in neural protection and repair after all kinds of brain damage.But to date,reports on hippocampal expression of activin βA and activin receptor mRNA in convlusive animal models are very rare；no information is available on changes in activin and inhibin protein levels in the mouse hippocampus after seizures ,nor are there reports on the effects of activin A exogenousapplication on seizures, epileptiform discharges and related neuropathology. In this study,pilocarpine(PC) was used to induce status epilepticus(SE) in mice and the behavioral seizures were classified as 0～Ⅴ stages according to Racine's standard. Animals that exhibited seizures above Ⅱ stage and lasted uninterruptedly for 1 hour served as SE group.Animals that did not have seizures or did not develop SE 1? h after PC administration served as non-status epilepticus group(NSE). Animals that administered nature saline(NS) other than PC served as control group. All animals were given an intraperitoneal(ip) injection of diazepam to suppress seizure activity immediately after experiencing 1 h of SE ,or 1? h after PC or NS administration for those animals in NSE and control groups. The time that animal had experienced 1h of SE was defined as 1h post-SE. Firstly, RT-PCR was used to study the changes of time course of hippocampal activinβA mRNA expression in SE and NSE mice；in situ hybridization was used to observe the distribution of activinβA mRNA in the hippocampus；cresyl violet staining was used to study the changes of hippocampal pathology. Secondly, western blotting was used to detect the dynamic changes of activin A and inhibin A proteins, and RT-PCR was used to detect the dynamic changes of activin receptorⅡA mRNA. Finally, using seizure score, EEG recording, cresyl violet and TUNEL staining ,the effects of recombinant human activin A(rhACT),which was injected intracerebroventricularly(icv) 1h before intraperitoneal injection of pilocarpine ,on PC-induced seizures and pathological changes of hippocampus were observed.The results showed that: 1) Prior to the beginning of SE(0h),the activin βA mRNA expression was transiently significantly lower than that of normal and NSE mice,but went up to control levels at 1h post SE. Fron then on, the level of activinβA mRNA still went up,and increased significantly at 3h post SE. The peak arrived at 6h post SE and could be...