Hypoxia preconditioning attenuates brain edema associated with kainic acid-induced status epilepticus in rats

Kainic acid (KA)-induced seizures elicit edema associated with necrosis in susceptible brain regions (e.g., piriform cortex and hippocampal CA, and CA , regions). To test the hypothesis that hypoxia preconditioning protects ag ainst KA-induced edema formation, adult male rats were exposed to a 9% O-2, 91% N-2 atmosphere for 8 h. KA (14 mg/kg, i.p.) was administered 1, 3, 7, or 14 days later. Regional analysis of edema indicated that hypoxia exposur e attenuated edema formation in piriform and frontal cortices and hippocamp us when KA was given 1, 3, or 7 days later but not 14 days after hypoxia. C ycloheximide (2 mg/kg s.c.) given 1 h prior to hypoxia prevented the protec tive effect of hypoxia on KA-induced edema attenuation in the piriform cort ex and hippocampus. Thus, hypoxic challenge induces a general adaptive resp onse that protects against the seizure-associated pathophysiology, with no direct relationship to seizure intensity. This response may involve stress- related transcription factors and effector proteins. (C) 1999 Elsevier Scie nce B.V. All rights reserved.