| Objective: To establish a rat model of aging aerobic exercise, after exercise, age-distribution of the soleus and gastrocnemius â… and type â…¡ rat muscle fibers were detected, measured skeletal muscle PGC-1α protein and mRNA expression levels, and MEF-2 mRNA expression levels analyzed between aerobic exercise on the aging rat skeletal muscle â…° and type â…± muscle fiber distribution effects, explore the role of PGC-1α in exercise-induced muscle fiber transformation, and its related factor MEF-2 relationship.Methods: Healthy male SD rats(Sprague-Dawley Rat) 4 months 16(408.65 ± 48.63g), 12 months of age 16(504.09 ± 40.79g) and 16 months of age 16(561.77 ± 28.56g), SPF level of animals, housed separately. Adaptive training 5 days, were randomly divided into 2 young control group(YC, n = 6), the youth sports group(YE, n = 10), middle-aged group(MC, n = 6) and youth sports group(ME, n = 10), middle-aged group(OC, n = 6) and middle-aged exercise group(OE, n = 10). Exercise group rats using treadmill exercise, the establishment of increasing loads in experimental animal models(gradient of 0 °, increasing strength to 19 m / min × 60 min, exercise intensity equivalent to 70% VO2max), training six days a week for a total training 8 weeks. After the end of the last 20 hours of training to take soleus and gastrocnemius, using ATP enzyme staining to identify muscle fiber types, with Western Blotting detection of PGC-1 α protein expression, real-time PCR to detect PGC-1α and MEF-2 mRNA expression levels.Results:(1) after 8 weeks the movement, in addition to OE group, the other rats in each group increased body weight. YC group which was significantly higher body weight, significant difference(p <0.01), while the rate of increase of other groups before and after experiment no significant(p> 0.05). Before the experiment MC group and OC group were significantly higher body weight YC group, with significant differences(p <0.01).(2) after eight weeks exercise, compared with the control group, YE group soleus â… muscle fiber number density increases, type â…¡ muscle fiber number density reduction, there was no significant difference; ME group soleus â… muscle fiber number density reduction, â…¡ type muscle fiber number density significantly increased(p <0.05); OE group â… soleus muscle fiber number density significantly reduced(p <0.05), increased the number of type â…¡ muscle fiber density.(3) 8 weeks exercise, compared with the control group, in addition to a significant reduction in ME group gastrocnemius â…¡ muscle fiber number density(p <0.01), but all other sports groups gastrocnemius â… and â…¡ muscle fiber number density was not significantly different.(4) between the control group, MC group gastrocnemius muscle PGC-1α protein expression was significantly higher than YC group, with significant differences(p <0.01). After eight weeks exercise, compared with the control group, YE group and gastrocnemius OE group PGC-1α protein expression in an average reduction of water and YE significant differences between groups, with statistical significance(p <0.05). ME group gastrocnemius muscle PGC-1α protein levels higher than the MC group, but the difference was not significant(p> 0.05).(5) among the control group, MC group soleus, gastrocnemius PGC-1 α mRNA expression of the highest level. Wherein, YC group was significantly lower than MC group was higher than OC groups. After eight weeks exercise, compared with the control group, all age groups soleus muscle movement, gastrocnemius PGC-1α mRNA expression was significantly increased(p <0.01).(6) among the control group, MC group soleus, gastrocnemius MEF-2 mRNA expression of the highest level, and the MC group soleus MEF-2 mRNA expression was significantly higher than the OC group(p <0.01). YC group gastrocnemius MEF-2 mRNA expression levels were significantly lower than MC group(p <0.01), and significantly higher than the OC group. After eight weeks exercise, compared with the control group, the exercise group soleus, gastrocnemius MEF-2 mRNA expression levels were significantly increased.Conclusions:(1) Rat natural condition of aging, soleus â… and â…¡ muscle fiber number density as a whole showed a decreasing trend after the first increase, gastrocnemius muscle of type â… , â…¡ muscle fiber number density of the overall decline.(2) exercise stress conditions, PGC-1α may promote the conversion of young rats soleus muscle fibers occurs, the direction of type â…¡ â†' â… type; young group soleus muscle fiber type conversion direction â†' â…¡ type â… and â… muscle fibers number density change is associated with PGC-1α protein expression was; the middle-aged group soleus muscle fiber type conversion direction â†' â…¡ type â…° increased PGC-1α protein expression can promote transformation.(3) exercise stress conditions, PGC-1α may promote the gastrocnemius muscle fibers in rats, and the direction of type â…¡ â†' â… type.(4) rest, the youth group of the protein PGC-1α expression mainly in slow-twitch; young and middle-age groups after exercise, expression of PGC-1α mainly in fast-twitch muscle.(5) exercise stress condition of aging in rat skeletal muscle PGC-1α and MEF-2mRNA expression levels were positively correlated. |
PDF Full Text Request