Cerebral protection by AMPA- and NMDA-receptor antagonists administered after severe insulin-induced hypoglycemia.
Excitatory amino acids are implicated in the development of neuronal cell damage following periods of reversible cerebral ischemia or insulin-induced hypoglycemic coma. To explore the importance of glutamate receptor activation in the posthypoglycemic phase, we exposed rats to 20 min of insulin-induced severe hypoglycemia. The rats were treated immediately after the hypoglycemic insult with four regimes of glutamate receptor antagonists: (1) the AMPA (alpha-amino-3-hydroxy-5-methyl-4-isoxazole propriate)-receptor antagonist NBQX [2.3-dihydroxy-6-nitro-7-sulfamoyl-benzo (F) quinoxaline] given as a bolus dose of 30 mg.kg-1 i.p., followed by an i.v. infusion of 225 micrograms.kg-1.min-1 for 6 h; (2) the non-competitive NMDA-receptor antagonist, dizocilpine (MK-801) 1 mg.kg-1 given i.v.; (3) a combined NBQX treatment, (a bolus dose of 10 mg.kg-1 i.p., followed by an i.v. infusion of 225 micrograms.kg-1.min-1 for 6 h), with dizocilpine 0.33 mg.kg-1 given twice i.p. at 0 and 15 min after recovery and (4) the competitive NMDA-receptor blocker CGP 40,116 [D-(E)-2-amino-4-methyl-5-phosphono-3- pentenoic acid] 10 mg.kg-1 given i.p. In the striatum, all glutamate receptor blockers significantly decreased neuronal damage by approximately 30%. An approximately 50% decrease in neuronal damage was demonstrated in neocortex and hippocampus following the combined treatment with NBQX and dizocilpine, while protection was variable following the treatment with a single glutamate-receptor antagonist.(ABSTRACT TRUNCATED AT 250 WORDS)
Laboratory for Experimental Brain Research, Lund University Hospital, Sweden.
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B
Nellgård
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T
Wieloch
D015763:2-Amino-5-phosphonovalerate / Q000031:analogs & derivatives / Q000627:therapeutic use; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002545:Brain Ischemia / Q000209:etiology / Q000517:prevention & control*; D016923:Cell Death / Q000187:drug effects; D016291:Dizocilpine Maleate / Q000627:therapeutic use; D004569:Electroencephalography / Q000187:drug effects; D018691:Excitatory Amino Acid Antagonists; D007331:Insulin Coma / Q000150:complications / Q000473:pathology / Q000517:prevention & control*; D008297:Male; D009336:Necrosis / Q000473:pathology; D009474:Neurons / Q000187:drug effects; D011810:Quinoxalines / Q000627:therapeutic use; D051381:Rats; D017208:Rats, Wistar; D018091:Receptors, AMPA; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors*
D018691:Excitatory Amino Acid Antagonists; D011810:Quinoxalines; D018091:Receptors, AMPA; D016194:Receptors, N-Methyl-D-Aspartate; C062865:2,3-dioxo-6-nitro-7-sulfamoylbenzo(f)quinoxaline; C064539:2-amino-4-methyl-5-phosphono-3-pentenoic acid; D016291:Dizocilpine Maleate; D015763:2-Amino-5-phosphonovalerate