The inhalation anesthetic desflurane induces caspase activation and increases amyloid β-protein levels under hypoxic conditions

Perioperative factors including hypoxia, hypocapnia, and certain anesthetics have been suggested to contribute to Alzheimer disease (AD) neuropathogenesis. Desflurane is one of the most commonly used inhalation anesthetics. However, the effects of desflurane on AD neuropathogenesis have not been previously determined. Here, we set out to assess the effects of desflurane and hypoxia on caspase activation, amyloid precursor protein (APP) processing, and amyloid beta-protein (A beta) generation in H4 human neuroglioma cells (H4 naive cells) as well as those over-expressing APP (H4-APP cells). Neither 12% desflurane nor hypoxia (18% O-2) alone affected caspase-3 activation, APP-processing, and A beta generation. However, treatment with a combination of 12% desflurane and hypoxia (18% O-2) (desflurane/hypoxia) for 6 h induced caspase-3 activation, altered APP processing, and increased A beta generation in H4-APP cells. Desflurane/hypoxia also increased levels of beta-site APP-cleaving enzyme in H-4-APP cells. In addition, desflurane/hypoxia-induced A beta generation could be reduced by the broad caspase inhibitor benzyloxycarbonyl- VAD. Finally, the A beta aggregation inhibitor clioquinol and gamma-secretase inhibitor L-685,458 attenuated caspase-3 activation induced by desflurane/ hypoxia. In summary, desflurane can induce A beta production and caspase activation, but only in the presence of hypoxia. Pending in vivo confirmation, these data may have profound implications for anesthesia care in elderly patients, and especially those with AD.