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Anesthesiology. 2009 May;110(5):1077-85. doi: 10.1097/ALN.0b013e31819daedd.

Dexmedetomidine attenuates isoflurane-induced neurocognitive impairment in neonatal rats.

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  • 1Department of Anaesthetics, Pain Medicine and Intensive Care, Imperial College London, London, UK.

Abstract

BACKGROUND:

Neuroapoptosis is induced by the administration of anesthetic agents to the young. As alpha2 adrenoceptor signaling plays a trophic role during development and is neuroprotective in several settings of neuronal injury, the authors investigated whether dexmedetomidine could provide functional protection against isoflurane-induced injury.

METHODS:

Isoflurane-induced injury was provoked in organotypic hippocampal slice cultures in vitro or in vivo in postnatal day 7 rats by a 6-h exposure to 0.75% isoflurane with or without dexmedetomidine. In vivo, the alpha2 adrenoceptor antagonist atipamezole was used to identify if dexmedetomidine neuroprotection involved alpha2 adrenoceptor activation. The gamma-amino-butyric-acid type A antagonist, gabazine, was also added to the organotypic hippocampal slice cultures in the presence of isoflurane. Apoptosis was assessed using cleaved caspase-3 immunohistochemistry. Cognitive function was assessed in vivo on postnatal day 40 using fear conditioning.

RESULTS:

In vivo dexmedetomidine dose-dependently prevented isoflurane-induced injury in the hippocampus, thalamus, and cortex; this neuroprotection was attenuated by treatment with atipamezole. Although anesthetic treatment did not affect the acquisition of short-term memory, isoflurane did induce long-term memory impairment. This neurocognitive deficit was prevented by administration of dexmedetomidine, which also inhibited isoflurane-induced caspase-3 expression in organotypic hippocampal slice cultures in vitro; however, gabazine did not modify this neuroapoptosis.

CONCLUSION:

Dexmedetomidine attenuates isoflurane-induced injury in the developing brain, providing neurocognitive protection. Isoflurane-induced injury in vitro appears to be independent of activation of the gamma-amino-butyric-acid type A receptor. If isoflurane-induced neuroapoptosis proves to be a clinical problem, administration of dexmedetomidine may be an important adjunct to prevent isoflurane-induced neurotoxicity.

PMID:
19352168
[PubMed - indexed for MEDLINE]
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