Ultrastructure of the blood-brain barrier of the gyrus hippocampal cortex in an experimental model of febrile seizures and with the use of a new generation antiepileptic drug - topiramate

The ultrastructure of the blood-brain barrier (BBB) of the gyrus hippocampal cortex in an experimental model of febrile seizures in rats and the effect of a new generation antiepileptic drug, topiramate, on the morphological status of this barrier were investigated. Advanced changes indicating a substantial increase in BBB permeability were observed in the animals with induced febrile seizures (FS), with approximately 2/3 of capillaries and perivascular astroglial processes being affected. Almost total occlusion of the capillary lumen was frequently seen, caused by damaged endothelial lining and by external pressure from markedly swollen perivascular astrocytic processes. Mitochondrial changes predominated among the abnormalities found in endoplasmic organelles of endothelial cells. Lesions in the BBB coexisted with damage to pyramidal neurons, mainly with features of aponecrosis ("dark neurons"). The study on topiramate seems to demonstrate its protective action on the BBB components of the ammonal cortex in the group receiving the drug as prevention, i.e. against febrile seizures. It was found to prevent marked BBB damage in over half of the capillaries. However, the application of topiramate directly after FS induction hod no distinct beneficial effect on the structural BBB components.