The effect of intravenous insulin on accumulation of excitotoxic and other amino acids in the ischemic rat cerebral cortex.
Insulin has been reported to be neuroprotective during cerebral ischemia/reperfusion. However, it may also increase the sensitivity of cultured cortical neurons to glutamate toxicity. The experiments described here utilized a rat four-vessel occlusion model with cerebral cortical windows to determine the effects of intravenous insulin, alone (I) or combined with glucose (IG) to maintain physiologic blood glucose levels, on the extracellular accumulation of amino acids in superfusates of the cerebral cortex. Aspartate, phosphoethanolamine, taurine and gamma-aminobutyric acid were increased in the I and IG groups and glutamate was increased in the IG group compared to controls during ischemia/reperfusion. Insulin treatment attenuated the rebound in cortical superfusate glucose levels in both groups of animals during reperfusion. The increases in amino acid release during reperfusion may be due to a lack of glycolytically derived energy available for amino acid uptake systems and ionic pumps.
Guyot
L L
LL
Department of Neurological Surgery, School of Medicine, Wayne State University, Detroit, MI 48201, USA. lguyot@voyager.net
Diaz
F G
FG
O'Regan
M H
MH
Ren
J
J
Phillis
J W
JW
D000818:Animals; D001224:Aspartic Acid / Q000378:metabolism; D001923:Brain Chemistry / Q000187:drug effects / Q000502:physiology; D002540:Cerebral Cortex / Q000098:blood supply / Q000378:metabolism*; D004734:Energy Metabolism / Q000187:drug effects / Q000502:physiology; D005947:Glucose / Q000378:metabolism / Q000494:pharmacology; D018698:Glutamic Acid / Q000378:metabolism*; D006003:Glycogen / Q000378:metabolism; D007003:Hypoglycemia / Q000378:metabolism; D007004:Hypoglycemic Agents / Q000494:pharmacology*; D007275:Injections, Intravenous; D007328:Insulin / Q000494:pharmacology*; D002546:Ischemic Attack, Transient / Q000378:metabolism*; D019344:Lactic Acid / Q000378:metabolism; D008297:Male; D009498:Neurotoxins / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015427:Reperfusion Injury / Q000378:metabolism; D013654:Taurine / Q000378:metabolism; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
D007004:Hypoglycemic Agents; D007328:Insulin; D009498:Neurotoxins; D013654:Taurine; D001224:Aspartic Acid; D019344:Lactic Acid; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid; D006003:Glycogen; D005947:Glucose