| （1.Departmen of Physical Education，National University of Defense Technology，Changsha 410072，China；2.Departmen of Physical Education，Hunan Agricultural University，Changsha 410128，China) Abstract: In order to probe into the mechanism of exercise preconditioning improving cerebral ischemic injury by basing the target nucleus on the striatum, the authors divided male Wistar rats randomly into a calm control mi-crodialysis group (CM), a calm control staining group (CS), an exercise preconditioning microdialysis group (EM) and an exercise preconditioning staining group (ES) (each of which consists of 10 rats), implanted a microdialysis probe guide cannula into the striatum of the rats in groups CM and EM, then let the rats in groups EM and ES un-dergo 4-week aerobic training after surgery recovery, performed middle cerebral artery occlusion surgery on all the rats after training was completed, applied the microdialysis-HPLC-electrochemistry combined technology to observe the changing of dopamine (DA), 5-hydroxytryptamine (5-HT), norepinephrine (NE) and their respective metabolites, dihy-droxy phenyl acetic acid (DOPAC), 5-hydroxy indole acetic acid (5-HIAA) and 3-methyl 4-hydroxy benzene ethylene gly-col (MHPG) in the extracellular fluid of the striatum of the rats in the process of ischemia and in reperfusion, and took out the brains of the rats in groups CS and ES for TTC staining after the rats had gone through 24 hours of recovery from middle cerebral artery occlusion surgery. From staining results the authors found that the damaged area of the striatum of the rats in group ES decreased significantly (P<0.05) as compared with that of the rats in group CS. From microdialysis research results the authors revealed the following findings: in the process of ischemia, the extracellular DA level of the striatum of the rats in groups CM and EM showed a trend of rapid increasing, the increasing magnitude of the rats in group EM was smaller than that of the rats in group CM (P<0.05), then the DA level of the rats in the two groups decreased gradually, and stabilized ba-sically at a level below the baseline in the process of reperfusion. The trend of changing of DA metabolite DOPAC was as follows: in the process of ischemia, the extracellular DOPAC of the striatum of the rats in two groups decreased rapidly, but the decreasing magnitude of the rats in group EM was smaller than that of the rats in group CM (P<0.05), then the DOPAC level of the rats in the two groups increased gradually, in the process of reperfusion, the DOPAC level showed a trend of rapid increasing followed by gradual decreasing. In the process of ischemia and reperfusion, the changing of the levels of 5-HT, NE and their respective metabolites was basically consistent with the trend of changing of DA and DOPAC. The said results indicated the followings: scientific and rational exercise preconditioning is an effective means to protect ischemic brain injury; in the process of ischemia and reperfusion, the changing of the levels of extracellular monoamine neurotrans-mitters and their metabolites in the striatum used as one of the target nuclei for exercise preconditioning to exert its nerve protecting function may be one of the ways for exercise preconditioning to realize its protecting function.
Key words: sports biochemistry；exercise preconditioning；cerebral ischemia；striatum；monoamine neuro-transmitter；metabolite；rat |
