Changes in blood-brain barrier permeability during hot water-induced seizures in rats

Abstract.   Hot water epilepsy (HWE) was induced in freely movingWistar rats by applying hot water jets over the head region. Thestatus of the blood-brain barrier (BBB) during the seizures andduring hot water-induced hyperthermia without seizures wasexamined using Evans blue dye. In order to investigate thecontribution of concomitant factors to this process,synchronized body temperature and blood pressure recordings werealso made. Tonic-clonic seizure activity was observed within anaverage of 3.9 min (SE=0.6 min) in the rats exposed to the hotwater jets; this treatment induced BBB opening in the corticaland deep brain areas. Body temperature and blood pressureincreased from 36.5°±0.3°C to 40.0°±0.2°C, and from 91±3 mmHg to153±4 mmHg, respectively. In the group of animals exposed to hotwater application without inducing seizures, there weresignificant increases both in blood pressure and bodytemperature; however, the extravasation of Evans blue was notpronounced in the brains. Hot water-induced seizures, increasedcerebrovascular permeability. Although high blood pressure andhyperthermia contribute to this permeability, the seizureactivity is the major factor in this change.