Study On Apoptosis In Skeletal Muscle Of Rats Trained During Long-Term Treadmill Aerobic Exercise

Apoptosis, or programmed cell death, is now recognized to be an important cellular event during normal development and in the progression of specific diseases. Apoptosis can be triggered by stimuli initiating outside of the cell, or within the mitochondria, leading to the activation of caspases and subsequent cell death. Although apoptosis has been widely studied in a variety of tissues over the last 5 years, skeletal muscle has been relatively ignored in this regard. Research on apoptosis in skeletal muscle has recently taken on a higher profile as the recognition emerges that it may be an important contributor to specific skeletal muscle pathologies and sports science. In skeletal muscle, very few studies have been done under specific exercise (e.g., exhausted treadmill training) conditions. Skeletal muscle is unique in that it is multi-nucleated, and evidence suggests that it can undergo individual myonuclear apoptosis as well as complete cell death. This review discusses the basic cellular mechanisms of apoptosis, as well as the current evidence of this process in skeletal muscle. The need for more work in this area is highlighted, particularly in exercise and training.To research and prove that apoptosis exists in skeletal muscle after different weeks training and how Se taken postpones the development of apoptosis. After one week adaptive feed 156 3-month-old male SD rats were divided into 3 groups at random: (1) sedentary group (2) trained group (3) Se taken trained group. Rats were actually divided into 26 small groups according to trained and sacrificed time: 24 hour recovery groups, no recovery groups and 3 hour recovery groups of after 1,2,3 and 4 weeks training respectively. At condition of slope 0, treadmill speed 25m/min, rats totally ran 33min which include 3min preparation, slow then fast, and finally at a constant speed. The formal trained time is 30min. The running intensity and load are invariable. Trial load is as same as the routine training. Decollation and remove of quadriceps femoris muscles were done respectively prior, after, and 3h after treadmill training. Quadriceps femoris muscle was separated into two parts: one part wasundergone hematoxylin-eosin (HE) in histological analysis, and the other part was undergone flow cytometry. That the karyon of cells appeared unclear, chromatin appeared condensed, karyon became packed against nuclear membrane, and nuclear membrane thickening was observed under microscope after HE dying processing. These phenomena showed that the cell apoptosis existed after exercise. In addition, observation indicated that the presence of apoptosis was in a large amount at the end of the first week of training, this situation decline gradually at the following three weeks. The same results also appeared in flow cytometry tests: The apoptosis rate was at the highest level at the end of the first week, and then decreased by the training weeks correspondingly. The Se taken can postpone the development of apoptosis, but this trend cannot last long. These results suggested that exercise is capable of bringing about apoptosis in skeletal muscle cells, and the apoptosis rate will decreased after rats bodies' adaptation to the exercise. Free oxygen radicals play an important role in muscle cell apoptosis induced by exercise. As a new developed antioxidant, Se helps to inhibit the occurrence of cells apoptosis at the early days. Long term Se taking may induce toxication.