Topical glucose and accumulation of excitotoxic and other amino acids in ischemic cerebral cortex.
Pre-ischemic hyperglycemia aggravates brain damage due to transient global ischemia as demonstrated by exacerbation of brain lesions. Lactacidosis and elevated glutamate levels have been implicated as mechanisms of the increased damage. Our objective was to determine the effects of different levels of glucose (0, 66.5, 450 mg/dL) in cortical superfusates on the ischemia/reperfusion-evoked release of amino acids from the rat cerebral cortex. Physiologic levels of glucose significantly reduced the amount of aspartate, glutamate and gamma-aminobutyric acid and the supra-physiologic levels of glucose reduced the amount of aspartate and phosphoethanolamine released from the cortex during ischemia/reperfusion in comparison with no glucose. The decrease in glutamate release may be due to increased availability of glucose for glycolysis with the subsequent formation of ATP and lactate, which has been shown to act as an energy source for neurons. The decreased levels may also reflect the continued energy-dependent uptake of glutamate by glial cells.
Guyot
L L
LL
Department of Neurological Surgery, School of Medicine, Wayne State University, Detroit, MI 48201, USA.
Diaz
F G
FG
O'Regan
M H
MH
Song
D
D
Phillis
J W
JW
D000818:Animals; D001224:Aspartic Acid / Q000378:metabolism; D001794:Blood Pressure; D002545:Brain Ischemia / Q000378:metabolism*; D002245:Carbon Dioxide / Q000097:blood; D002540:Cerebral Cortex / Q000378:metabolism*; D004983:Ethanolamines / Q000378:metabolism; D018846:Excitatory Amino Acids / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism* / Q000494:pharmacology; D018698:Glutamic Acid / Q000378:metabolism; D006943:Hyperglycemia / Q000378:metabolism; D008297:Male; D010100:Oxygen / Q000097:blood; D051381:Rats; D017207:Rats, Sprague-Dawley; D015427:Reperfusion Injury / Q000378:metabolism; D013654:Taurine / Q000378:metabolism; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
D004983:Ethanolamines; D018846:Excitatory Amino Acids; D002245:Carbon Dioxide; D013654:Taurine; D001224:Aspartic Acid; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid; C005448:phosphorylethanolamine; D005947:Glucose; D010100:Oxygen