| Summary: | 碩士 === 國立成功大學 === 生理學研究所 === 93 === Although the acute stress response is important for the survival of animals, stress is a well-known cardiovascular disease risk factor. In contrast, regular exercise has been shown to have beneficial effects in the prevention of cardiovascular diseases. Long-term wheel running suppresses excessive increases in blood pressure and heart rate in rats under stress. How chronic exercise ameliorates the stress-associated adverse effects is an intriguing question. An early study has shown that restraint stress evokes HSP72 expression in the aorta. Recent results also indicate that habitual physical activity enhances stress-induced HSP72 induction in brain and various peripheral tissues, including adrenal gland, liver, and immune tissue. Moreover, elevated HSP72 expression in nucleus tractus solitarii (NTS) and rostral ventrolateral medulla (RVLM) improves the baroreflex capacity when rats are under heat stroke or sepsis. We, therefore, hypothesize that the beneficial effects of chronic exercise on cardiovascular function may be accompanied with elevated stress-induced HSP72 expression in various peripheral and central tissues. In this study, male Wistar rats underwent exercise training for 8 weeks either by exposure to a running wheel (voluntary exercise) or by running on a treadmill (compulsive exercise). At the end of exercise training period, they were subjected to restraint/water exposure stress before sacrifice by CO2 euthanasia. Western blot analysis was used to quantify the protein levels of HSP72 in adrenal gland, aorta, NTS and RVLM. Our results showed that 1) blood pressure was elevated and maintained at high level in rats subjected to restraint/water exposure stress, but only transiently elevated in rats under restraint stress alone; 2) both adrenal gland and aorta expressed HSP72 protein when rats were subjected to restraint/water exposure stress; 3) voluntary exercise training induced the HSP72 expression in adrenal gland and RVLM; 4) compulsive exercise training induced the HSP72 expression in adrenal gland and aorta; and 5) stress induced additional HSP72 elevation in adrenal gland and aorta of compulsive exercise trained rats. In conclusion, the HSP72 expression is differentially upregulated in various peripheral and central tissues by two different types of exercise training.
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