Affiliation:
1. Lecturer.
2. House Officer.
3. Medical Student.
4. Senior Research Technician.
5. Ph.D. Student.
6. Professor in Biophysics Section, The Blackett Laboratory, and Department of Anaesthetics, Pain Medicine and Intensive Care, Imperial College London.
7. Sir Ivan Magill Professor, Department of Anaesthetics, Pain Medicine and Intensive Care.
Abstract
Background
Anesthetics, including isoflurane and nitrous oxide, an antagonist of the N-methyl-D-aspartate subtype of the glutamate receptor, have been demonstrated to induce apoptotic neurodegeneration when administered during neurodevelopment. Xenon, also an N-methyl-D-aspartate antagonist, not only lacks the characteristic toxicity produced by other N-methyl-D-aspartate antagonists, but also attenuates the neurotoxicity produced by this class of agent. Therefore, the current study sought to investigate xenon's putative protective properties against anesthetic-induced neuronal apoptosis.
Method
Separate cohorts (n = 5 or 6 per group) of 7-day-old rats were randomly assigned and exposed to eight gas mixtures: air, 75% nitrous oxide, 75% xenon, 0.75% isoflurane, 0.75% isoflurane plus 35% or 75% nitrous oxide, 0.75% isoflurane plus 30% or 60% xenon for 6 h. Rats were killed, and cortical and hippocampal apoptosis was assessed using caspase-3 immunostaining. In separate cohorts, cortices were isolated for immunoblotting of caspase 3, caspase 8, caspase 9, and cytochrome c. Organotypic hippocampal slices of postnatal mice pups were derived and cultured for 24 h before similar gas exposures, as above, and subsequently processed for caspase-3 immunostaining.
Results
In vivo administration of isoflurane enhances neuronal apoptosis. When combined with isoflurane, nitrous oxide significantly increases whereas xenon significantly reduces apoptosis to a value no different from that of controls. In vitro studies corroborate the ability of xenon to attenuate isoflurane-induced apoptosis. Isoflurane enhanced expression of indicators of the intrinsic and common apoptotic pathways; this enhancement was increased by nitrous oxide but attenuated by xenon.
Conclusions
The current study demonstrates that xenon prevents isoflurane-induced neonatal neuronal apoptosis.
Publisher
Ovid Technologies (Wolters Kluwer Health)
Subject
Anesthesiology and Pain Medicine
Cited by
235 articles.
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