Effects Of Recombinant Human Growth Hormone On Expression Of IGF-1,Survivin And Caspase-3 In Rats With Cerebral Ischemia-reperfusion Injury

Background and ObjectiveThe cerebral ischemia-reperfusion is a common of ischemic cerebrovascular disease. The most important pathophysiological changes after cerebral ischemia are ischemic lesions and the death of neurons in the ischemic penumbra. To save survival neurons in the ischemic penumbra has become the main purpose of treatment. How to reduce cell death caused by cerebral ischemia-reperfusion is a hot spot in clinical research.Growth hormone can promote metabolism, growth and development.Growth hormone directly exerts its biological effects by combining target tissue-specific receptors or through the growth hormone/insulin-like growth factor (GH/IGF) axis indirectly exerts its biological effects. Growth hormone is used to treat growth hormone deficiency dwarfism, burns, inflammation and infertility. Recent studies found that growth hormone can reduce brain injury caused by ischemia and hypoxia, inhibit apoptosis and promote cell survival. Whether growth hormone plays a good therapeutic effect in treatment of cerebral ischemia is still unknown.Studies have confirmed that Insulin-like growth factor-1 (IGF-1) has neuroprotective effects. IGF-1 contributes to recovery of damaged nerve cells. Survivin is the member of IAP family. The expression of Survivin could be promoted after cerebral ischemia-reperfusion injury. We found that the relationship between IGF-1 and Survivin was studied in tumor, but was not in cerebral ischemia-reperfusion injury. Caspase-3 is the main implementation protein of the end stage of apoptosis, and is closely related to neuronal apoptosis caused by cerebral ischemia.Given the above, we established the rats models with cerebral ischemia-reperfusion injury and observed the expression of IGF-1, Survivin and Caspase-3. To analysis correlation between IGF-1, Survivin and Caspase-3. We also investigate the effects of recombinant human growth hormone on expression of IGF-1, Survivin and Caspase-3 in rats with cerebral ischemia-reperfusion. All of these were aimed to investigate the neural protection mechanism of growth hormone and to provide a theoretical basis in treatment of ischemic cerebrovascular disease.Materials and methods1 Animal grouping and delivery Method72 clean grade healthy male Sprague Dawley rats, weighing 250-280g(from the Experimental Animal Center of Zhengzhou University), were randomly divided into the sham operation group, the model group and the treatment group. Each group were divided into 1d,3d,5d and 7d four time points after surgery. We injected rhGH 0.1U·kg-1·d-1 in treatment group, once every 24 hours. Sham operation group and model group were injected the same dose of saline.2 Model preparation and target detectionThe model of focal cerebral ischemia-reperfusion injury was made by occluding middle cerebral artery(MCA) for 2 hours and reperfusing. In the different time points after treatment, rats were anesthetized and perfused with physiological saline and 4% paraformaldehyde through heart. Subsequently, the brain-tissues of all rats were took out and fixed. And using immunohistochemistry technique to detect the expression of IGF-1, Survivin and Caspase-3 in three groups respectively. Then, using image analysis system to measure average gray of the positive zone.3 Statistical MethodsThe data was expressed by mean±standard deviation(X±S), and analyzed with one-way analysis of variance and correlation analysis by SPSS 13.0 statistic software. Significance level is judged by a=0.05.Results1 The dynamic change of IGF-1IGF-1 in sham-operated group had little expression. The expression of IGF-1 in the model group had markedly increased. The expression of IGF-1 in the treatment group was higher than in model group at the same time. Comparing with three groups, there were significant differences(P<0.05).2 The dynamic change of SurvivinSurvivin in sham-operated group had little expression. The expression of Survivin in the model group had markedly increased. The expression of Survivin in the treatment group was higher than in model group at the same time. Comparing with three groups, there were significant differences(P<0.05).3 The dynamic change of Caspase-3Caspase-3 in sham-operated group had little expression. The expression of Caspase-3 in the model group had markedly increased. The expression of Caspase-3 in the treatment group was significantly decreased than in model group at the same time. Comparing with three groups, there were significant differences(P<0.05).4 Correlation analysisSurvivin positively correlated with the expression of IGF-1 (r=0.872, P<0.05). Caspase-3 negatively correlated with the expression of Survivin (r=-0.882, P<0.05).Conclusions1.After cerebral ischemia-reperfusion injury, the expression of Survivin is positively correlated with the expression of IGF-1, and negatively correlated with the expression of Caspase-3.2.rhGH can induce the expression of IGF-1 and Survivin, and inhibit the expression of Caspase-3 after cerebral ischemia-reperfusion injury. It is suggested that rhGH plays the important role on neuron protection.