BLOCKADE OF AMPA RECEPTORS REDUCES BRAIN EDEMA FOLLOWING OPENING OF THE BLOOD-BRAIN-BARRIER

The aim of our study was to evaluate whether blockade of alpha-amino-3 -hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptors could re duce brain edema in two experimental models of edema following opening of the blood-brain barrier (BBB). The brain specific gravity was dete rmined 2 h after opening the BBB by a 30-s infusion of protamine sulfa te (10 mg in 200 mul 0.9% NaCl) or arabinose (1.5 or 1.8 mol/L, 0.06 m l . s-1) into the fight internal carotid artery. Cisternal CSF was wit hdrawn for albumin determination before the carotid infusion and befor e killing 2 h later. After infusion of protamine sulfate or arabinose, CSF albumin increased in all groups. The brain specific gravity was s ignificantly lower in the right than in the left (control) frontal, pa rietal, and occipital cortex and striatum. NBQX dihydroxy-6-nitro-7-su lfamoylbenxo(F)quinoxaline), an AMPA receptor antagonist, given intrav enously 10 min after opening the BBB (5 mg/kg), significantly increase d the specific gravity in the treated rats (p < 0.01 for the differenc e from control rats) without reducing CSF albumin or albumin extravasa tion in the brain as evaluated with Evans blue. We hypothesize that in tracerebral (glial?) AMPA receptors may play a role in brain edema fol lowing opening of the BBB.