Effects of dexmedetomidine on activity of c-Jun N-terminal kinase during cerebral ischemia-reperfusion in rats / 中华麻醉学杂志

ABSTRACT

Objective To evaluate the effects of dexmedetomidine on the activity of c-Jun N-terminal kinase (JNK) during cerebral ischemia-reperfusion (I/R) in rats.Methods Eighty-one pathogen-free male Sprague-Dawley rats,aged 8 weeks,weighing 180-220 g,were randomly divided into 3 groups (n=27 each) using a random number tablesham operation group (group S);cerebral I/R group (group CI/R);dexmedetomidine group (group Dex).The rats were anesthetized with intraperitoneal 10％ chloral hydrate 300 mg/kg.Cerebral ischemia was induced by occlusion of the middle cerebral artery for 2 h followed by 24 h of reperfusion in CI/R and Dex groups.The middle cerebral artery was only exposed but not occluded in group S.Dexmedetomidine 3 μg/kg was injected via the tail vein immediately before ischemia followed by infusion at a rate of 3 μg · kg-1 · h-1until 24 h of reperfusion in group Dex,while the equal volume of normal saline was given in S and CI/R groups.The rats were sacrificed at 24 h of reperfusion,and their brains were removed for determination of cerebral infarct size (by TTC staining),brain water content ((wet weight-dry weight)/wet weight × 100％),cell apoptosis (by TUNEL) and expression of phosphorylated JNK (p-JNK) protein (by Western blot analysis).Apoptotic index was calculated.Results Compared with group S,the brain water content,apoptotic index and cerebral infarct size were significantly increased,and the expression of p-JNK was up-regulated in CI/R and Dex groups.Compared with group CI/R,the brain water content,apoptotic index and cerebral infarct size were significantly decreased,and the expression of p-JNK was down-regulated in group Dex.Conclusion Dexmedetomidine reduces cerebral I/R injury through decreasing the activity of JNK and inhibiting cell apoptosis in rats.