EFFECT OF TEMPERATURE ON KAINIC ACID-INDUCED SEIZURES

The effects of body temperature on kainic acid-induced seizures and se izure-related brain damage were examined in rats. In rats with status epilepticus induced by intraperitoneal injection of 12 mg/kg of kainic acid (KA), ictal discharges were decreased by 50% when body temperatu re was lowered to 28 degrees C and nearly abolished when body temperat ure was lowered to 23 degrees C. In rats with mild hypothermia (28 deg rees C), the duration of ictal discharges following KA injection was s ignificantly lower than in rats with normal body temperature. No detec table hippocampal cell loss was observed in rats with hypothermia to 2 8 degrees C whereas gross cell loss in the hippocampus was observed in all rats with KA injection at normal body temperature. In contract to hypothermia, hyperthermia markedly aggravated the seizures and hippoc ampal damage induced by KA. Following elevation of body temperature to 42 degrees C KA (12 mg/kg) resulted in severe seizures and all rats d ied of tonic seizures within 2 h. Furthermore, 6 mg/kg of KA administe red to rats with a body temperature of 41-42 degrees C, resulted in up to 4 h of continuous ictal discharges whereas no continuous ictal dis charges were observed after the same injections in rats with normal bo dy temperature. Histological examination in rats receiving 6 mg/kg of KA revealed severe cell loss in the hippocampus in rats with hyperther mia but not in rats with normal temperature. These results demonstrate that body temperature plays an important role in the control of epile ptic seizures and seizure-related brain damage. These data suggest tha t hypothermia may be useful in reducing seizures and associated brain damage and that hyperthermia should be avoided in status epilepticus.