Effects Of Mild And Moderate Hypothemia Therapy On Expression Of Cerebral Neuron Apoptosis Related Proteins And Glial Fiber Acidic Protein After Rat Cardio-pulmonary Resuscitation

PartⅠ Establish and evaluation a model of Mild and Moderate Hypothemia After Rat Cardio-pulmonary ResuscitationObjective Cardiac arrest induced by asphyxia method was used to create CPR model.To establish and evaluate the model of Mild and Moderate Hypothemia After rat Cardio-pulmonary ResuscitationMethods0.3 ml/100 g of 10 % chloral hydrate was injected intraperitoneally for anesthesia, tracheostomy tube was placed, and cannula was inserted into the femoral artery and femoral vein. Arterial blood pressure was monitored and Standard II lead electrocardiogram was recorded. Rectal temperature was monitored using electron thermometer by placing the probe 1.5 cm from the anus. Rats were stabilized for 15 min after operation, and rats with obviously abnormal heart rate and blood pressure were excluded. Trachea was clipped to cause sudden cardiac arrest(ECG presented as ventricular fibrillation, pulseless electrical activity or asystole, systolic pressure dropped to<25 mm Hg and arteriopalmus disappeared). Airway was opened after being clipped for 6min and connected with animal ventilator for ventilation. External chest compression was applied, and electric defibrillation and 1.5 mg/ kg of lidocaine intravenous injection were applied if there was ventricular fibrillation. Compression was terminated when spontaneous circulation was restored(HR?170/min and systolic pressure?90 mm Hg).Resuscitation was terminated if spontaneous circulation was not restored after 6 min.Ventilation was terminated when spontaneous breath was restored. After monitoring the vital signs for approximately 35 min, femoral arterial and venous cannula were removed and vessels were ligated. 0.12 ml/100 g of 10 % chloral hydrate was immediately injected intraperitoneally when rats became conscious.Rats of Control group were placed at roomtemperature without inducing hypothermia, and incandescent light bulb was used when body temperature dropped. Body temperature was stabilized at 36.5-37.2 °C within 1 h after resuscitation. Ice bag was used to induce hypothermia after resuscitation for hypothermia group, and optimum temperature was reached(33/30 °C) within 30 min after hypothermia. If body temperature deviated from the optimum temperature, regulation was applied. When the body temperature was higher than the standard, diluted ethanol was sprayed or combined with electric fan to reduce temperature; when the body temperature was lower than the standard, rats were place at room temperature(around 25 °C) for rewarming. The fluctuation range was controlled within± 0.3°C.Results TMild and moderate hypothermia of rat After Rat Cardio-pulmonary Resuscitation was reached(33/30 °C) within 30 min after hypothermia.Conclusion Successfully established a model of Mild and Moderate Hypothemia After Rat Cardio-pulmonary Resuscitation.PartⅡ The effects of different degrees of hypothermia on Expression of brain tissue apoptosis after Rat cardio-pulmonary resuscitation(CPR).Objective To explore the effects of different degrees of hypothermia on brain tissue apoptosis after cardio-pulmonary resuscitation(CPR).Methods: 30 SD rats were randomly divided into control group(normothermia),33 °C hypothermia group and 30°C hypothermia group with ten rats in each. Rats in control group received routine treatment at 25 °C room temperature after CPR; Rats in mild hypothermia and moderate hypothermia groups were given hypothermia treatment after CPR. Brain tissue in all groups was taken 24 h after CPR, and immunohistochemistry was used to detect the caspase-3 in cerebral cortex. Western blotting was used to detect Bcl-2 and Bax protein expression.Results Compare to the control group, caspase-3 expression in cerebral neurons in hypothermia group was significantly decreased(p<0.01), which was lower in 30°C group than that in 33°Cgroup(p?0.05); Bcl-2 expression level in hypothermia group was significantly increased(p<0.01), which was higher in 30°C hypothermia group than that in33°C hypothermia group(p<0.05);The level of Bax had no significant difference amongthe three groups.Conclusion hypothermia treatment by decreasing caspase-3 expression and increasing Bcl-2 expression to promote brain cell signaling transduction, and further inhibited cell apoptosis and reduced brain injury. Moderate hypothermia therapy is more effective than mild hypothermia in preventing brain injure.Part Ⅲ The effects of different degrees of hypothermia on Expression of Glial Fiber Acidic Protein After Rat Cardio-pulmonary ResuscitationObjective To explore the effects of different degrees of hypothermia on Expression of Glial Fiber Acidic Protein after Rat cardio-pulmonary resuscitation(CPR).Methods 30 SD rats were randomly divided into control group(normothermia), 33 °C hypothermia group and 30°C hypothermia group with ten rats in each. Rats in control group received routine treatment at 25 °C room temperature after CPR; Rats in mild hypothermia and moderate hypothermia groups were given hypothermia treatment after CPR. Brain tissue in all groups was taken 24 h after CPR, and immunohistochemistry was used to detect the glial fiber acidic protein(GFAP) expression in astrocyte.Results Compare to the control group, GFAP level in hypothermia groups was significantly increased(p<0.01).Conclusion Hypothermia-regulated GFAP expression by decreasing caspase-3expression and increasing Bcl-2 expression to promote brain cell signaling transduction,and further inhibited cell apoptosis and reduced brain injury. Moderate hypothermia therapy is more effective than mild hypothermia in preventing brain injure.