Increased duration of isoflurane exposure reduces cerebral infarct and improves neurological function in focal cerebral ischemia in rats




Gaidhani, Nikhil


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Isoflurane is a widely used gas anesthetic for surgical procedure in rodents. Using a rodent model of transient ischemic stroke (transient midcerebral artery occlusion; tMCAO) our laboratory has demonstrated that longer exposure period to isoflurane anesthesia significantly reduce cerebral ischemic damage. The objective of this study was to demonstrate the correlation between the duration of isoflurane exposure and isoflurane-induced neuroprotection after tMCAO. Three groups were created based on total duration of isoflurane exposure during tMCAO and rats were randomly assigned to these groups; Isoflurane-20 min, Isoflurane-40 min, and Isoflurane-90 min. Focal cerebral ischemia was induced by a transient (90 min) middle cerebral artery occlusion in the rats from each group. Measurements of cerebral infarct volumes and neurological behavioral tests were performed 24hrs post-MCAO. We report that rats from Isoflurane-20 min group sustained significantly larger cerebral infarct than animals from Isoflurane-40 min and Isoflurane-90 min groups. Rats from Isoflurane-90 min groups showed near complete resistance to ischemic damage. Neurological function also significantly improved with increased duration of isoflurane exposure as evidenced by the results of Bederson and Cylinder tests. Our results clearly demonstrate the neuroprotective effect of isoflurane during ischemic stroke and provide strong evidence that increasing the duration of isoflurane exposure during the tMCAO procedure significantly reduce brain injury and improve neurological function after focal cerebral ischemic stroke.