Sugiura Takao, Ito Naoko, Goto Katsumasa, Naito Hisashi, Yoshioka Toshitada, Powers Scott K
Department of Exercise and Health Sciences, Yamaguchi University, Yamaguchi, 753-8513 Japan.
J Physiol Sci. 2006 Dec;56(6):393-9. doi: 10.2170/physiolsci.RP006906. Epub 2006 Oct 21.
We tested the hypothesis that estrogen administration would retard immobilization-induced muscle atrophy in adult male rats. The rats were injected for 24 days with either estrogen (40 microg/kg(-1), beta-estradiol 3-benzoate in olive oil vehicle), or vehicle alone. At day 14 of estrogen treatment, the hindlimb muscles of one leg were immobilized in plantar flexion position by the use of a plaster cast. Following 10 days of immobilzation, the atrophic and the contralateral soleus muscles were both removed and analyzed to determine the level of muscle atrophy along with the measurement of the protein levels of Cu-Zn-superoxide dismutase (Cu-Zn-SOD), heat shock protein 72 (HSP72), and selected proteases. Compared to placebo animals, estrogen treatment significantly reduced (-35%) muscle atrophy. Further, estrogen significantly abridged the expression of the calcium-activated protease, calpain, in the atrophied hindlimb muscle. In contrast, estrogen treatment did not alter the protein levels of HSP72 in the immobilized soleus muscle. These results support the postulate that estrogen attenuates the rate of disuse muscle atrophy, partly because of reductions in immobilization-induced calcium-activated protease levels.
给予成年雄性大鼠雌激素可延缓制动诱导的肌肉萎缩。给大鼠注射雌激素（40微克/千克⁻¹，溶于橄榄油载体中的β-雌二醇3-苯甲酸盐）或仅注射载体，持续24天。在雌激素治疗的第14天，通过石膏固定将一条腿的后肢肌肉固定于跖屈位。固定10天后，切除萎缩的比目鱼肌和对侧比目鱼肌并进行分析，以确定肌肉萎缩程度，并测量铜锌超氧化物歧化酶（Cu-Zn-SOD）、热休克蛋白72（HSP72）及选定蛋白酶的蛋白质水平。与给予安慰剂的动物相比，雌激素治疗显著减轻了（35%）肌肉萎缩。此外，雌激素显著降低了萎缩后肢肌肉中钙激活蛋白酶钙蛋白酶的表达。相比之下，雌激素治疗并未改变固定比目鱼肌中HSP72的蛋白质水平。这些结果支持以下假设：雌激素可减缓废用性肌肉萎缩的速度，部分原因是固定诱导的钙激活蛋白酶水平降低。
