Ballak Sam B, Jaspers Richard T, Deldicque Louise, Chalil Sreeda, Peters Eva L, de Haan Arnold, Degens Hans
School of Healthcare Science, Manchester Metropolitan University, Manchester, United Kingdom; Laboratory for Myology, MOVE Research Institute Amsterdam, Faculty of Human Movement Sciences, VU University Amsterdam, Amsterdam, The Netherlands.
Laboratory for Myology, MOVE Research Institute Amsterdam, Faculty of Human Movement Sciences, VU University Amsterdam, Amsterdam, The Netherlands.
Exp Gerontol. 2015 Feb;62:23-31. doi: 10.1016/j.exger.2014.12.020. Epub 2015 Jan 3.
Sarcopenia contributes to the decreased quality of life in the older person. While resistance exercise is an effective measure to increase muscle mass and strength, the hypertrophic response may be blunted in old age.
To determine 1) whether hypertrophy in the m. plantaris of old mice was blunted compared to adult and 2) whether this was related to a reduced satellite cell (SC) density and 3) how resveratrol affects hypertrophy in old mice.
In adult (7.5 months, n=11), old (23.5 months, n=10) and old-resveratrol-treated (n=10) male C57BL/6J mice, hypertrophy of the left m. plantaris was induced by denervation of its synergists. The contralateral leg served as control.
After six weeks, overload-induced myofiber hypertrophy and IIB-IIA shift in myofiber type composition were less pronounced in old than adult mice (P=0.03), irrespective of resveratrol treatment. Muscles from old mice had a lower SC density than adult muscles (P=0.002). Overload-induced SC proliferation (P<0.05) resulted in an increased SC density in old, but not adult muscles (P=0.02), while a decrease occurred after resveratrol supplementation (P=0.044). Id2 and myogenin protein expression levels were higher in old than adult muscles (P<0.05). Caspase-3 was expressed more in hypertrophied than control muscles and was reduced with resveratrol (P<0.05).
The blunted hypertrophic response in old mice was associated with a lower SC density, but there was no evidence for a lower capacity for proliferation. Resveratrol did not rescue the hypertrophic response and even reduced, rather than increased, the number of SCs in hypertrophied muscles.
肌肉减少症会导致老年人生活质量下降。虽然抗阻运动是增加肌肉质量和力量的有效措施,但在老年时肥大反应可能会减弱。
确定1)与成年小鼠相比,老年小鼠跖肌的肥大是否减弱;2)这是否与卫星细胞(SC)密度降低有关;3)白藜芦醇如何影响老年小鼠的肥大。
在成年(7.5个月,n = 11)、老年(23.5个月,n = 10)和老年白藜芦醇处理组(n = 10)雄性C57BL/6J小鼠中,通过去神经支配其协同肌诱导左跖肌肥大。对侧腿作为对照。
六周后,无论白藜芦醇处理如何,老年小鼠中由过载诱导的肌纤维肥大和肌纤维类型组成从IIB向IIA的转变均不如成年小鼠明显(P = 0.03)。老年小鼠的肌肉SC密度低于成年肌肉(P = 0.002)。过载诱导的SC增殖(P < 0.05)导致老年肌肉而非成年肌肉中的SC密度增加(P = 0.02),而补充白藜芦醇后SC密度降低(P = 0.044)。老年肌肉中Id2和肌细胞生成素蛋白表达水平高于成年肌肉(P < 0.05)。半胱天冬酶-3在肥大肌肉中的表达高于对照肌肉,且白藜芦醇可使其降低(P < 0.05)。
老年小鼠中减弱的肥大反应与较低的SC密度有关,但没有证据表明其增殖能力较低。白藜芦醇未能挽救肥大反应,甚至降低了肥大肌肉中SC的数量,而非增加。