ABSTRACT
Objective To explore any effect of calorie restriction on the proliferation of satellite cells in the skeletal muscles of elderly rats.Methods Twelve male C57BL rats aged 12 or 13 months were randomly divided in to an experimental group and a control group,each of 6.The control group was fed 75.09 kJ/d as normal,while the experimental group was provided with 45.05 kJ/d (60％ of normal).The intervention lasted for 15 weeks and each rat's weight was measured every week.After the intervention,limb muscle satellite cells were sorted by fluorescenceactivated cell sorting after digestion,and the cell cycle was analyzed.Western blotting was used to assess the expression of cyclin A,D1 and E.Results There was no significant difference in the average weight of the two groups before the experiment.After the 15 weeks the average weight of the experimental group had decreased significantly (to 19.5±0.4 g),and it was significantly lighter than that of the control group (31.9±0.5 g).The average percentage of the satellite cells in the G0/G1 phase had decreased significantly in the experimental group,but the percentage in the S phase had increased significantly.The expression of cyclin A and E was significantly greater in the experimental group compared with the control group,but the expression of cyclin D1 had decreased significantly.Conclusion Caloric restriction can delay the proliferation of satellite cells in the skeletal muscles of elderly mice.
ABSTRACT
Objective To explore the inhibitory effect of pulsed ultrasound on skeletal muscle fibrosis after injury.Methods Thirty elderly male rats with gastrocnemius muscle injury were divided into an ultrasound group (UG) and a control group (CG) using a random number table.The injured muscles in the UG were treated using pulsed ultrasound (frequency 1 MHz,average strength 40 mW/cm2,duty cycle 20％) for 10 min daily from day 3 after the injury.The CG was given no treatment.On days 3,7,14,21 and 28 after the injury,histological and immunohistochemical analyses of the gastrocnemius muscles of both groups were performed.Results The collagen fiber mean optical density of the muscles increased gradually after the injury and reached its peak on day 21.It was significantly lower in the UG than in the CG on each test day.The expression of α-SMA increased gradually after the injury,but it too remained significantly lower in UG than that in CG.Conclusion Pulsed ultrasound may reduce collagen formation and α-SMA expression in injured skeletal muscle,and then inhibit muscle fibrosis.