Expression Of Ephrin B3in The Hippocampus Of Epileptic Rats Induced On Cortical Dysplastic Rats

Object:To investigate the expression of ephrin B3in the hippocampal formation of in a rat model of cortical dysplasia with epilepsy, and to explore the potential interaction of cortical dysplasia and epilepsy.Methods:1. The animal models of MCD were established by BCNU (Carmustine)-exposure in uterus. Nine pregnant Sprague-Dawley rats were injected intraperitoneally with15mg/kg of BCNU on embryonic day17(E17), their pups were enrolled in experiment group. Another ten were injected with a corresponding volume of5%dextrose in water on E17. Their offspring were recuited in control group. The model of cortical malformations in experiment group were confirmed by abnormal offspring growth and development, brain wet weight and brain tissue HE staining.2. The offspring experiment group on postnatal60(P60) were induced status epilepticus (SE) by intraperitoneal Lithium Chloride-Pilocarpine(PILO) injection in order to set up malfunction cortical development epileptic group (MCD+EP group) while the offspring in the same group that did not recive pilocarpine injection were recruited into common epileptic model (EP group).There are four groups in our research:MCD+EP group, EP group, MCD group and CON group.3. Compare the latency and duration of SE onset and mortality of two groups and assess the seizure susceptibility.4. Investigate the mRNA and protein expression level of Ephrin B3in hippocampus of different group using immunohistochemistry, immunofluorescence and Real-time PCR at different time points (1,14and60days) after SE.Results:1. Compared to the control group, cortical dysplasia pups grew retardation and HE staining showed a thinner brain cerebral cortex, layered structure disorder ectopic cortical and hippocampal neurons. We established the cortical dysplasia rats successfully.2. The MCD model rats showed a shorter latent period (P<0.05), longer duration(P<0.01), and increased mortality than the control rats significantly after SE(P<0.01).3Immunohistochemistry and immunofluorescence confirmed that ephrinB3protein was predominantly located within the dentate gyrus granule layer; The expression of ephrinB3in MCD+EP group was significantly increased (P<0.01); The expression of MCD+EP group was lower at1day and14day post SE, while it increased at the time point of60day. Compared to CON group, the expression of ephrinB3in EP group also significantly increased (P<0.01).4. Real-time PCR showed that the ephrinB3mRNA expression levels was significantly higher in MCD+EP group than in EP group, and the expression decreased in the acute and resting phase, but increased in chronic phase.Conclusions:1. EphrinB3might participate in regulating excitability of brain network in the hippocampus of cortical dysplastic rats.2. EphrinB3may be related to the mechanism of epileptogenicity in MCD.