Abstract
<i>Background</i> Acute ischemic stroke causes long-term neurological and neurobehavioral dysfunctions. With the development of clinical medicine, the importance of pre-ischemic exercise intervention has been gradually recognized, but its mechanism remains to be further explored. <i>Objective</i> This study investigates the effects of different exercise intensity preconditioning in changes of hippocampal neurons and the expression of Gadd45β and DNA-PKcs in the hippocampal region after cerebral ischemia-reperfusion in rats. <i>Method</i> 160 SD rats were divided into control group (n=40), cerebral ischemia reperfusion group (I/R group, n=40), middle intensity exercise preconditioning group (EI 1+I/R group, n=40), high intense exercise preconditioning group (EI 2+I/R group, n=40). Stroke was induced by improved Pulsinelli four blood vessel blocking after exercise preconditioning. Morphological changes of neurons in the hippocampal region of rats were observed by HE staining at 6 h, 1d, 3d and 7d after ischemia in each group. Immunohistochemistry method was used to detect the expression of Gadd45β and DNA-PKcs in hippocampus CA1. The mRNA level of Gadd45β and DNA-PKcs in hippocampal CA1 was detected by Real Time PCR. <i>Results</i> Compared with I/R group, the neuronal cell necrosis of was alleviated in EI 1+I/R group, but more serious in EI 2+I/R group; The expression of Gadd45β and DNA-PKcs were significantly higher in the EI 1+ I/R group, but lower in EI 2+I/R group (<i>P</i><0.01). <i>Conclusion</i> Moderate intensity exercise preconditioning can improve the survival of neurons after cerebral ischemia-reperfusion injury in rats. However, high-intensity motor preconditioning increased the damage and loss of neurons, and its mechanism may be related to the regulation of the expression of Gadd45β and DNA-PKcs in the hippocampus of cerebral ischemia-reperfusion rats, thus protecting and promoting the function of DNA repair system.
Highlights
About 75% of the existing patients with cerebrovascular diseases in China lose their ability to work to varying degrees
Is the protective effect of pre-ischemic exercise on the brain after stroke related to the damage repair mechanism that triggers the body's regulatory DNA?Based on the above problems, the present study investigated the differences and changes in the expression of Gadd45β and DNA-PKcs in the hippocampal region of cerebral tissue during ischemia-reperfusion after two kinds of exercise preconditioning with different intensity, so as to find a new way for the protective mechanism of ischemic neurons
The results of this study showed that the expression of Gadd45β and DNA-PKcs protein and mRNA in the hippocampus of rats with moderate intensity exercise training increased significantly after modeling compared with that of the I/R group
Summary
About 75% of the existing patients with cerebrovascular diseases in China lose their ability to work to varying degrees. Studies have shown [5, 6] that extensive repeated exercise training before stroke can induce cerebral ischemia tolerance and has neuroprotective effects. When brain tissue is ischemia and hypoxia, the endogenous defense mechanism of the body will be activated, inducing the production of a series of DNA repair proteins and antioxidant enzymes to eliminate excessive free radicals. If this process is inhibited, DNA damage accumulation will be aggravated, cell damage will occur, and ischemia damage will be accumulated [8,9,10]. With the development of clinical medicine, the importance of pre-ischemic exercise intervention has been gradually recognized, but its mechanism remains to be further explored
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