Changes in anesthetic sensitivity and glutamate receptors in the aging canine brain.

TitleChanges in anesthetic sensitivity and glutamate receptors in the aging canine brain.
Publication TypeJournal Article
Year of Publication2000
AuthorsMagnusson KR, Scanga C, Wagner AE, Dunlop C
JournalThe journals of gerontology. Series A, Biological sciences and medical sciences
Volume55
Issue9
PaginationB448-54
Date Published2000 Sep
ISSN1079-5006
KeywordsAging, Analysis of Variance, Anesthetics, Inhalation, Animals, Brain, Cerebral Cortex, Dizocilpine Maleate, Dogs, Dose-Response Relationship, Drug, Excitatory Amino Acid Antagonists, Female, Glutamic Acid, Hippocampus, Isoflurane, Male, Neurotransmitter Agents, Radiopharmaceuticals, Receptors, AMPA, Receptors, Glutamate, Receptors, N-Methyl-D-Aspartate, Tritium
Abstract

This study investigated whether the aging process in dogs is associated with an increased sensitivity to inhalation anesthesia and whether age-related changes in glutamate receptors are related to the increased sensitivity. The mean minimum alveolar concentration (MAC) of isoflurane was 1.82 +/- .08% for 2-3 year olds and 1.45 +/- .06% for 11 years olds, indicating that there was an increased potency of isoflurane in the older dogs as compared to the young. These older animals also showed a significant decrease in binding of [3H]glutamate and [3H]dizocilpine ([3H]MK801) to N-methyl-D-aspartate (NMDA) receptors in multiple cortical and hippocampal regions. The density of binding to NMDA receptors in the cortex, using a single concentration of ligand, correlated significantly with individual MAC values. These results demonstrate that dogs experience an increase in anesthetic potency with increased age, similar to humans, and that age-related changes in the NMDA receptor may represent one mechanism underlying this increased sensitivity to anesthesia.

Alternate JournalJ. Gerontol. A Biol. Sci. Med. Sci.