Glutamate receptor antagonists inhibit calpain-mediated cytoskeletal proteolysis in focal cerebral ischemia

• Published in: Brain research Vol. 810; no. 1; pp. 181 - 199
• Main Authors: Minger, Stephen L, Geddes, James W, Holtz, Mary L, Craddock, Susan D, Whiteheart, Sidney W, Siman, Robert G, Pettigrew, L.Creed
• Format: Journal Article
• Language: English
• Published: London Elsevier B.V 09-11-1998; Amsterdam Elsevier; New York, NY
• Subjects: Animals; Biological and medical sciences; Blotting, Western; Calpain; Calpain - antagonists & inhibitors; Cerebral Infarction - physiopathology; Cerebral ischemia; Cytoskeleton - drug effects; Cytoskeleton - enzymology; Excitatory Amino Acid Antagonists - pharmacology; Immunohistochemistry; Ischemic Attack, Transient - enzymology; Male; Medical sciences; Microtubule-associated protein; Microtubule-Associated Proteins - metabolism; Neurology; Neuronal degeneration; Pipecolic Acids - pharmacology; Quinoxalines - pharmacology; Rats; Rats, Inbred SHR; Receptors, Glutamate - drug effects; Spectrin - metabolism; Synaptic Transmission - drug effects; Synaptic Transmission - physiology; tau Proteins - metabolism; Vascular diseases and vascular malformations of the nervous system; Neuronal degeneration; Calpain; Cerebral ischemia; Microtubule-associated protein; Rat; Cysteine endopeptidases; Cardiovascular disease; Glutamate receptor; Vascular disease; Ischemia; Proteolysis; Degeneration; Microtubule associated protein; Antagonist; Cerebrovascular disease; Nervous system diseases; Enzyme; Rodentia; Cerebral disorder; Peptidases; Vertebrata; Experimental disease; Mammalia; Animal; Central nervous system disease; Hydrolases; Cytoskeleton; Brain (vertebrata)
• ISSN: 0006-8993; 1872-6240
• DOI: 10.1016/S0006-8993(98)00921-4

Excitatory amino acids may promote microtubular proteolysis observed in ischemic neuronal degeneration by calcium-mediated activation of calpain, a neutral protease. We tested this hypothesis in an animal model of focal cerebral ischemia without reperfusion. Spontaneously hypertensive rats were treated with 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo-(F)quinoxaline (NBQX), a competitive antagonist of the neuronal receptor for α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), or
cis-4-[phosphono-methyl]-2-piperidine carboxylic acid (CGS 19755), a competitive antagonist of the
N-methyl-
d-aspartate (NMDA) receptor. After treatment, all animals were subjected to permanent occlusion of the middle cerebral artery for 6 or 24 h. Infarct volumes measured in animals pretreated with CGS 19755 after 24 h of ischemia were significantly smaller than those quantified in ischemic controls. Rats pretreated with NBQX showed partial amelioration of cytoskeletal injury with preserved immunolabeling of microtubule-associated protein 2 (MAP 2) at 6 and 24 h and reduced accumulation of calpain-cleaved spectrin byproducts only at 6 h. Prevention of cytoskeletal damage was more effective after pretreatment with CGS 19755, as shown by retention of MAP 2 immunolabeling and significant restriction of calpain activity at both 6 and 24 h. Preserved immunolabeling of tau protein was observed at 6 and 24 h only in animals pretreated with CGS 19755. Western analysis performed on ischemic cortex taken from controls or rats pretreated with either NBQX or CGS 19755 suggested that loss of tau protein immunoreactivity was caused by dephosphorylation, rather than proteolysis. These results demonstrate a crucial link between excitotoxic neurotransmission, microtubular proteolysis, and neuronal degeneration in focal cerebral ischemia.