Impact Of Preventive Use Of Cromakalim On MGluR1a And EAAT-2 In Rats With Cerebral Ischemia-reperfusion Injury

Objective To investigate the prophylactic use of the ATP-sensitive potassium channel opener cromakalim on neurological function and cerebral infarct size, as well as glutamate receptor 1αand glutamate transporter 1 expression in rats with cerebral ischemia-reperfusion injury, and to explore action mechanisms underlying reduced glutamate excitotoxicity and neuroprotection in rats.Methods Fifty four male, Wistar rats, aged 3-4 months, were randomly assigned to three groups (n=18):sham-surgery, model, and cromakalim. The Zea Longa Intraluminal thread methods were used to establish middle cerebral artery occlusion in rats from the model and cromakalim groups. Rats from the sham-surgery group were subjected to exposed common carotid artery, external carotid artery, and internal carotid artery, without occlusion. Cromakalim (10 mg/kg) was administered 30 minutes prior to middle cerebral artery occlusion, but there was no intervention in the model and sham-surgery groups. At 24 hours post-surgery, neurological behavioral functions were evaluated using Bederson's test, cerebral infarction volume was determined following tetrazolium chloride staining, glutamate receptor 1αand glutamate transporter 1 (EAAT-2) expressions were detected using immunohistochemistry and and the contents of neuron [Ca2+]i were determined. and to explore action mechanisms underlying reduced glutamate excitotoxicity and neuroprotection in rats with Cerebral Ischemia-reperfusion Injury. All data were expressed as mean±SD. Statistical analysis was carried out by one-way ANOVA.Results1,Neurobehavioral function scoresthe model and cromakalim groups exhibited significantly greater neurobehavioral functional scores than the shams-surgery group (P< 0.01). Compared with the model group, neurobehavioral functional scores were significantly improved in the cromakalim group (P<0.05).2,Cerebral infarction volumeTTC staining results showed that uniform staining in both cortical hemispheres of the sham-surgery group, indicating no infarction. In the model and cromakalim groups, a large, pale, infarcted region was observed. Compared with the model group, infarction volume was significantly reduced in the cromakalim group (P<0.05)。3,mGluRl a expression in ischemic rat cortexImmunohistochemical results revealed a large number of mGluRla-positive, darkly stained cells in the ischemic cortex and hippocampus in the model group, but very light staining in the sham-surgery and cromakalim groups. Results of absorbance in the cortical area showed that, compared with the sham-surgery group, the model group exhibited significantly increased mGluRla expression (P<0.05). Compared with the model group, mGluRla expression was significantly reduced in the cromakalim group (P<0.05)4,EAAT-2 expression in ischemic rat cortexImmunohistochemistry results revealed a large number of EAAT-2-positive cells in the cortex of the sham-surgery group, but few in the model and cromakalim groups. Compared with the sham-surgery group, hippocampal EAAT-2 expression was significantly reduced in the model and cromakalim groups (P<0.05). Compared with the model group, hippocampal EAAT-2 expression was significantly increased in the cromakalim group (P<0.05).5,neuron [Ca2+]i in the brain tissue.Compared with the sham-surgery group, the neuron [Ca2+]i in the brain tissue exhibited significantly increased in the model group (P<0.01); Compared with the model group the neuron [Ca2+]i in the brain tissue was significantly reduced in the cromakalim group (P< 0.01).Conclusion1,Preventive use of Cromakalim could improve neurological function and reduce cerebral infarction volume in rats with cerebralischemia-reperfusion injury, this result indicates that the preventive use of Cromakalim could reduce cerebral ischemia-reperfusion iInjury. 2,Preventive use of Cromakalim could reduce glutamate receptor 1αexpression and enhance EAAT-2 expression in rats with cerebralischemia-reperfusion injury, this result indicates that the preventive use of Cromakalim could reduce glutamate excitotoxicity and neuroprotection in rats.3,Preventive use of Cromakalim could reduce neuron [Ca2+]i in the brain tissue in rats with cerebralischemia-reperfusion injury, it shows that preventive use of Cromakalim could protect neurons through reduced calcium overload.