Objective:To correlate diffuse cortical dysplasia(DCD) epileptogenicity and the expression of GABAARα1 in adult rat with DCD by γ-ray irradiated injury.Methods:To establish γ-ray-induced model of DCD in rat

and newborn Wistar rats were allowed to survive for 14~16 weeks before HE

Nissl Stain

Timm’s histochemical method and SABC immunohistochemistry.We observed the structure of cortical regions and hippocampal formation with naked eyes and under a light microscope

and assessed the hippocampal mossy fiber sprouting after HE staining

Nissl staining and Timm’s histochemical method.The comparisons between every two groups were performed with Nemenyi test.We observed the expression of GABAARα1 subunit in cortical regions and hippocampal formation in the animal model and quantitatively analyzed using immunohistochemistry of GABAARα1 subunit.Results:Normal rats and irradiated pregnant rats didn’t have any seizure.F1 generation rats had seizure by chance.EEG showed no typical sharp waves

or spikes.In utero irradiation of fetal rats had served as an injury-based animal model of cortical dysplasia and neuronal heterotopia.Exposure of fetal rats to a single dose of γ-irradiation on embryonic day 17 resulted in microcephaly

diffuse cortical dysplasia

neuronal heterotopia

heterotopic neurons in the hippocampus

and hypoplasia of the corpus callosum.The mossy fiber sprouted in hippocampi CA3 area bilaterally

however there was no mossy fiber sprouting in controls or irradiated rats(P <0.05).Neonatal γ-ray irradiated injury could result in CD in cerebral cortex and mossy fiber sprouting in hippocampi CA3 area.There were chances of GABAARα1 subunit in cortical dyspiasia and hippocampal formation.Only the optical densities of GABAARα1-immunoreactive neurons located at Fr

HL

Par1

Par2

CA1

CA2

CA3 and DG area were significant different(P <0.05) between the experimental groups and the two control groups.Conclusion:These studies provide important mechanisms of epileptogenicity involving mossy fiber sprouting in hippocampi CA3 area and hyperexcitability of the cortical synapse network adjacent to cerebral cortex.