Research Of The Mechanisms And Effect Of Erythropoietin On Neuronal Mitochondria In Rats During Ischemia-reperfusion Injury

Chapter 1. Establishment of a Middle Cerebral Artery Occlusion (MCAO) model in SD Rats.Objective: To establish a Middle Cerebral Artery Occlusion(MCAO) model in SD Rats,to build a ischemia-reperfusion injury model, for next step of the research.METHODS: Thirty six SD rats are randomly divided into three groups: Sham group(n=12),Ischemia/reperfusion group(n=12) and Control group(n=12). Models of left cerebral ischemia-reperfusion (2 hours) were duplicated in Ischemia/reperfusion group. The rats in Sham group were only treated by carotid arterial isolation without ischemia reperfusion and intraperitoneal injection of anything.And nothing was done to Control group before Rats were killed. The changes of neurological scores and cerebral infarction volume were observed at 72 hours postoperatively in all groups to estate the model.Result: Cerebral infarction volume: It is obviously bigger in the rats of Ischemia-reperfusion group than that in the control group and sham group. Neurological scores: It is obviously lower in ischemia-reperfusion group than that in control group and sham group.Conclusion: A Middle Cerebral Artery Occlusion (MCAO) model in SD Rats is a successful ,repeatable model to observe the changes during the ischemia-reperfusion injury for the next step of research. Chapter 2. Antioxidative Effects of Erythropoietin on mitochondria of SD rats after focal cerebral ischemia.Objective: To observe the antioxidative effects of Erythropoietin on mitochondria of SD rats after focal cerebral ischemia.METHODS: Forty SD rats are randomly divided into four groups: EPO group(n=10),Ischemia/reperfusion group(n=10), Control group(n=10) and Sham group(n=10). Models of left cerebral ischemia-reperfusion (2 hours) were duplicated In EPO group and ischemia/reperfusion group. EPO group were treated with intraperitonal injection of EPO at a dose of 3000U/Kg mixed with the same dose of saline, while the Ischemia/reperfusion group with the same dose of saline. The rats in Sham group were only treated by carotid arterial isolation without ischemia reperfusion or intraperitoneal injection of anything.And nothing was done to Control group before Rats are killed. The changes of the activity of superoxide dismutase (SOD) and concentrations of malondialdehyde (MDA), nitric oxide(NO) and activity of Na+-K+-ATPase in the neuronal mitochondria were observed at 72 hours postoperatively in all groups.Result: (1) Activity of SOD,Na+-K+-ATPase: It is obviously higher in EPO group than in ischemia/reperfusion group.(2)Concentrations of malondialdehyde (MDA),nitric oxide of the brain tissue :It is obviously lower in EPO group than in ischemia/reperfusion group。Conclusion: Erythropoietin can provide neural protection against focal cerebral ischemia-reperfusion injury through suppressing oxidative damage,reducing the produce of free radicals and stabilizing the function of mitochondria and enhancing activity of Na+-K+-ATPase. Chapter 3. Protective Effects of Erythropoietin on Mitochondrial Function and Structure of SD RatsAIMS: To observe Erythropoietin's protective effects on mitochondrial fuction and structure of SD rats during brain ischemia/reperfusion injury.METHODS: Forty SD rats are randomly divided into four groups: EPO group (n=10), Ischemia/reperfusion group(n=10), Control group(n=10) and Sham group(n=10). Models of left cerebral ischemia-reperfusion (2 hours) were duplicated In EPO group and ischemia/reperfusion group. EPO group were treated with intraperitonal injection of EPO at a dose of 3000U/Kg mixed with the same dose of saline, while the Ischemia/reperfusion group with the same dose of saline. The rats in Sham group were only treated by carotid arterial isolation without ischemia reperfusion or intraperitoneal injection of anything.And nothing was done to Control group before Rats are killed. The changes activity of Na+-K+-ATPase in the neuronal mitochondria, and Caspase-3 postive neurons'number by means of immunohistochemistry, Mitochondrial membrane potential and mitochondrial structure were observed at 72 hours postoperatively in all groups.Result: (1) mitochondrial membrane potential,Na+-K+-ATPase: It is obviously higher in EPO group than that in ischemia/reperfusion group.(2) Number of Caspase-3 postive neurons': It is obviously lower in EPO group than in ischemia/reperfusion group. (3) Structure of neuron in EPO group is more contact than that in ischemia-reperfusion group.Conclusion: EPO can protect mitochondrial function and structure from brain ischemia/reperfusion injury.