| Summary: | 碩士 === 南台科技大學 === 生物科技系 === 100 === Background: Recent studies demonstrated that exercise ameliorated physical and cognitive impairments of patients suffering from the CNS disorders, including stroke and spinal cord injury. Although many aspects of the signal transduction pathways mediate exercise induced improvement in motor and cognition functions are elucidated, little is known about the molecular events interrelating physiological stress with Heat shock proteins, following physical exercise. However, many factors have an effect on survival of neuronal cells, and not enough studies have been performed to provide an understanding of survival of neuronal cells.
Aim: This study was done to identify whether pre-conditioning exercise has neuropro-tective effects against cerebral ischemia, through enhance brain BBB integrity and HSP72, 20 expression.
Materials and Methods: Male Wistar rats were randomly divided into the following four groups: (1) sedentary with sham operation group (Sham), (2) exercise with sham operation group (Ex), (3) sedentary with middle cerebral artery occlusion (MCAo) induced stroke group (MCAo), (4) exercise with stroke group (Ex/ MCAo). All exercise rats were trained to run on the treadmill as accommodation for 3 weeks. The accommodation lasted for three days, and rats failed to run the minimum amount of distance of the treadmill (600m) daily were excluded. After 3 weeks, rats were received with or without MCAo induced stroke. All rats were put in standard cage and allowed spontaneous recovery after stroke. Three days after MCAo surgery, rat brains will be removed and assay with molecular expression as follow: (1) TTC stain for infarction volume measurement. (2) Western blot for HSP20, 25, and 72 expression. (3) Immunofluorescence stain for neuron apoptosis and HSPs co-expression. (4) Evans blue extravasation and brain dry/wet ratio for BBB integrity assay. (5) Incline plane and mNSS score for motor function assay.
Results: We found that, compared with sedentary control animals, exercise significantly increased brain tissue HSP72 and HSP20 contents. Neuroprotection was based on levels of apoptosis (TUNEL) and infarct volume (TTC staining). Immunofluorescence stain was used for cellular expression of HSP72 and HSP20. Significant (P<0.05) up-regulation of HSP72 and HSP20 after 3 weeks of exercise coincided with significant (P<0.05) reduction in neuronal apoptosis and brain infarct volume. Since MCAo induces apoptotic neuron death, we also studied the co-expression of HSP72 and HSP20 with markers of apoptosis. No HSP72 or 20-positive neurons were found to be apoptotic, as assessed by both TUNEL, DAPI and HSP72 or HSP20 immunoreactivity. Brain edema and Evans Blue leakage were both significantly (P<0.05) reduced after stroke in the exercised group, in association with reduced brain infarct volume and neurological deficits. We found that exercise increased the level of HSPs in the cortex, striatum, hippocampus, and hypothalamus and improved the motor behavior index.
Conclusions: Our results indicate that pre-ischemic exercise reduces brain injury by improving cell survival and enhancing BBB integrity in stroke. This study suggests that the neuroprotective effect of physical exercise is associated with HSPs overexpression. The results indicate that physical exercise might be an effective method to establish ischemic preconditioning.
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