| Abstract: | 1.山藥調控卵巢切除大白鼠心肌細胞凋亡及其保護機制的訊息途徑之研究
世界衛生組織的統計中指出，心血管疾病的罹患率高居不下。同時國內衛生署所公佈的十大死因中，心血管疾病一直榜上有名。其中男性罹患率要比女性的罹患率高出許多，但女性的這項優勢，在停經之後消失，因此，主導月經週期的荷爾蒙雌性素，被認為具有保護心臟的功能。
另一方面，為了減輕停經期婦女的不適，大多數的婦女均會使用荷爾蒙取代療法(Hormone Replacement therapy；HRT)，以減輕停經所帶來的症狀，並得以維持生活品質。然而HRT這項療法，確有其不可忽略的副作用：乳癌。我們希望能以含有Diosgenin(結構類似雌性素的化合物)的山藥(Dioscorea spp.)取代HRT，並加以探討，山藥是否具有保護心肌細胞的功能？
我們以卵巢切除的母鼠，模擬停經期婦女的情況，再餵食不同劑量的山藥，探討此對心肌細胞的分子機制有何影響？我們首先以H&E stain跟Trichrome Masson兩種染色法證明，山藥具有減緩卵巢切除對心肌細胞所造成的傷害，同時在TUNEL assay的分析中，我們也發現適量山藥可抑制心肌細胞的凋亡。接著我們以Western blot以及RT-PCR兩種方式，證明了卵巢切除後會透過Death receptor跟Mitochondria造成細胞凋亡，同時對於MAPK pathway中的ERK和P38，亦有不同程度的影響。最後，我們證實了適量山藥會跟雌性素一樣，透過ERα進而活化PI3K/Akt pathway，以達到保護心肌細胞的成效。
透過我們的實驗結果，證明了適量山藥的確具有保護心肌細胞的作用，也許在不久的將來，可以應用在臨床上，藉此取代HRT。
2.運動調控基因性肥胖症Zucker Rats心肌細胞凋亡之影響
近年來國人的生活品質改善，加上飲食日趨西化，導致肥胖人數遽增。肥胖除了自我形象的認知改變外，更會增加慢性病的罹患率，像是糖尿病、高血壓和心臟病等等。而根除肥胖問題的方法，即是從日常生活的飲食控制及運動做起。
研究指出，運動會增加AMP-Activated Protein Kinase；AMPK的活性。AMPK為體內的能量調節者，當AMP：ATP的比值改變時，AMPK即會被活化，提高醣類跟脂肪的分解，並降低其合成。目前只知AMPK會因運動、缺氧、缺能而被活化，但其間的機制仍不十分清楚，因此，我們利用Zucker Rats，先天基因缺陷的肥胖鼠，模擬人類肥胖的模式，給予運動訓練後，犧牲後取其心臟做研究，觀察心肌細胞在運動後的變化為何
結果顯示，運動後的這組，不管胖或瘦的Zucker Rats，心肌細胞凋亡的情形，比未接受運動訓練的要嚴重，在此同時，我們也偵測了AMPK的上游，Akt蛋白的活性，發現其表現量有微幅上揚的傾向。另外，我們也發現了，運動的刺激下，會活化GPCR，進而調節PKCδ的活性，達到一個保護心肌細胞的作用。
顯而易見的，運動訓練對心肌細胞的刺激，除了凋亡的途徑活化外，亦引發了保護心肌細胞的路徑被活化，同時Zucker Rats的體重亦因運動訓練而下降，足見運動對於減肥，具有直接效果。
1.Reveal the signaling pathways of Dioscorea extract suppress cardiomyocytes apoptosis and provide protective effects in ovariectomized rats
World Health Organization indicat that Cardiovascular disease is the leading cause of mortality. The phenomenon also in our country. The cardiovascular disease is significantly lower in women than in men until menopause, after which the cardiovascular risk of women accelerates to equal that of men. Therefore this observation suggests a possibility that female sex hormones, such as estrogen, may have a favorable cardiovascular role.
On the other hand, in order to diminish the syndrome of menopausal, most of women will use the Hormone Replacement Therapy(HRT). But one thing that let us attention, the side effect of HRT：Breast cancer. The structure of compound that called Diosgenin which included in Dioscorea spp. was similar to estrogen. We wish to substitute HRT and explore how mechanism of protect to cardiomyocytes？
Ovariectomized rats, aminal models of the status of postmenopausal women, were feed with various dose of Dioscorea spp., for a month, rats hearts were isolated to analysis effects of apoptotic and survival mechanism in cardiomyocytes. First we use H&E stain and Trichrome Masson stain to prove that ovariectomized injury in cardiomyocytes could be to decrease by Dioscorea spp. Analysis to TUNEL assay, we found that apoptosis in cardiomyocytes were suppressed by Dioscorea spp. Go on to analysis with western blot and RT-PCR, we demonstration that apoptosis in cardiomyocytes were induced by death receptor dependent pathway and mitochondria dependent pathway. We also found ERK and P38 were influence by ovariectomized injury which could induced by Dioscorea spp. Finally, we confirm Dioscorea spp. was similar to estrogen could active ERα and PI3K/Akt pathway, that could protect to cardiomyocytes.
In our study, that prove Dioscorea spp. could protect to cardiomyocytes. Maybe can application in clinical and to substitute HRT in future.
2.Investigation the effect of exercise on cardiomyocytes apoptosis in hereditary obese Zucker Rats
The life style was change in recent years, there were more and more persons face of obesity. The body image was change and the risk of chronic disease were increase in obesity persons, such as diabetes mellitus、hypertension and heart disease etc. To solve that problem of obesity are food control and exercise.
Indication of many study, exercise could activate AMP-Activated Protein Kinase；AMPK. AMPK was an important regulator of energy. When the ratio of AMP：ATP was drop, AMPK were activated, that the carbohydrate and fat were to decomposed. AMPK activates the catabolic pathway and inhibits the anabolic pathway. But who could activates AMPK？ We don’t understand. Up to now we know that AMPK could activated by exercise、ischemia and lack of energy. Therefore we use Zucker Rats that have inborn of hereditary obese, mimic the model of obesity in human. Exercise training for one hour in everyday continues eight weeks. After exercise training, Zucker Rats were scarificed then isolated the heart to study.
After exercise training, no matter lean or obesity Zucker Rats, apoptosis in cardiomyocytes was vary critical. At the same time, we also analysis Akt that the upstream of AMPK, which was increase. We also found GPCR could induced by exercise training, then activates PKCδ to protect the heart.
Stress of exercise training to cardiomyocytes, except activates apoptosis pathway also could induces that protective pathway to heart. In addition apoptosis were activated, the body weight of Zucker Rats were got lost by exercise training. |
