Plasticity Of Neuron Axon Initial Segment Of Cortex In Rats With Malformation Of Cortical Development

Object To study the development differences between the malformation of cortical development (MCD) and normal Sprahue Dawley (SD) rats. To observe the expression changes of layer-specific markers Maplb in MCD rats’ cortex. To investigate the expression of AnkG in MCD rats cortical AIS area, reveals the morphological changes of AIS area in the MCD rats’cortex, and then explore the significance to epilepsy susceptibility of MCD animal model.Methods The experimental group rats were induced cortical malformation with BCMU by intraperitoneal injection at the17th day of pregnantce. The control group were injected with10%glucose solution at the same time. Select the day of birth (P0),7days after birth (P7),14days (P14),28days (P28) and56days (P56) as the observation time, then we selected two groups with the same numbers of pups at each observation time, taking the weight, the brain wet weight, and height measurement. We randomly selected six pups from each group at each observation time for the preparation of paraffin sections and frozen sections. Observation of morphological changes of the two groups’cortex by HE staining, immunohistochemical staining was used to observ MAP1B expression in the cortex, and verify the success of the MCD model, immunofluorescence staining method used to observe the AnkG expression differences in the two sets of cortex.Results There were no significant difference (P>0.05) in weight between two groups at P0, the difference was significant starting from P7(P<0.05); There were no significant difference (P>0.05) in brain wet weight between two groups at PO and P7(P>0.05), it was significant starting from the time of P14(P<0.05); There were no significant difference (P>0.05) in height at any observation time. MAP1B expressed in Ⅱ, Ⅲ, Ⅴ layer in the temporal cortex of control group, no significant expression changes happened at any observation time, MAP1B expressed in Ⅱ, Ⅲ, Ⅳ layer in MCD group. There were significant differences in morphology of AnkG+cell between two groups, the normalization of AIS morphology in MCD group was later than that in the control group. The length of the AnkG+cell in MCD group were shorter than that in the control group from the time of P7(P<0.05).Conclusions The weight development of MCD group lagged far behind that in the control group from the first week after birth; The brain wet weight development of MCD group lagged far behind that in the control group from the second week after birth; There was no significant difference in height between two groups; Maplb+cell expressed in Ⅱ Ⅲ Ⅴ layer in the nomal group; The expression pattern of Maplb changed from different area in the MCD group, it expressed in Ⅱ, Ⅲ, Ⅳ layer in the temporal cortex; There were significant differences in the morphology of AIS between two group, There were significant differences in the length of AIS between two group from the first week after birth:the length of AIS is shortened in the MCD cortex, the normalization of AIS morphology delayed.