Abstracts

Rationale: WAG/Rij rats, a genetic model for generalized absence epilepsy, display the important characteristics of childhood absence epilepsy. The barrier type of brain capillary endothelial cells is severely affected in many epilepsy disorders including absence seizures. Methods: In this study, we used offsprings displaying the behavioral phenotype characterized by rotational movements of genetically epileptic WAG/Rij mothers and fathers. At the time of experiments, these rats were at least 6 months years old. In this subpopulation of WAG/Rij rats, we recorded EEG and rotational movements of the head and trunk using video-camera system. To show the functional and morphological alterations in blood-brain barrier (BBB) integrity, electron microscopic assessment of horseradish peroxidase (HRP) permeability was made. Results: Macroscopic observation of Vibratome sections of brains revealed a widespread pattern of HRP extravasation in cortical and subcortical regions of the rats. Ultrastructurally, the data revealed frequent vesicles containing HRP reaction products in the cytoplasm of capillary endothelial cells in cerebral cortex, hippocampus and amygdale regions of brain. Tight junctions (TJs) between adjacent endothelial cells were ultrastructurally intact and no sign of paracellular passage of HRP reaction products was noted. Conclusions: This study demonstrates that BBB permeability to HRP is increased in these genetically epileptic WAG/Rij animals with rotational movement. Rotational genetically generalized absence epilepsy must be differentiated within its genetic model. Further studies are needed to confirm whether the phenomenon is a behavioral disorder or of epileptic origin.