LETTERS TO THE EDITOR: Letters & Announcements
We are aware of the literature cited by Fodale and Santamaria in their letter and agree that inhibition of nicotinic acetylcholine receptors by certain general anesthetics is a plausible explanation for the learning impairment we observed in rats after isoflurane-nitrous oxide anesthesia (1). However, we know of no study that demonstrates long-lasting effects of a single general anesthetic administration on this or any other neurotransmitter receptor system. Furthermore, most general anesthetic agents act on multiple receptors (e.g., GABA and NMDA receptors) that participate in learning (2) and there are other possible explanations for our observations (3). Therefore, although we have experiments underway to investigate the mechanisms involved, we stand by our assertion that the etiology of postanesthetic learning impairment is unknown.
Deborah J. Culley, MD
Gregory Crosby, MD
1. Culley DJ, Yukhananov RY, Baxter MG, Crosby G. Memory effects of general anesthesia persist for weeks in young and aged rats. Anesth.Analg 2003; 96: 1004–9.
2. Krasowski MD, Harrison NL. General anaesthetic actions on ligand-gated ion channels. Cell Mol.Life Sci 1999; 55: 1278–303.
3. Jevtovic-Todorovic V, Hartman RE, Izumi Y, et al. Early exposure to common anesthetic agents causes widespread neurodegeneration in the developing rat brain and persistent learning deficits. J.Neurosci 2003; 23: 876–82.