Exercise and Biochemical Nutrition Laboratory , Exercise Nutrition and Resistance Training Research Unit, Department of Health, Human Performance, and Recreation ; Institute for Biomedical Studies, Baylor University , TX, USA.
Department of Exercise and Sports Sciences, University of Mary Hardin Baylor , Belton, TX 76513.
J Sports Sci Med. 2006 Dec 15;5(4):672-81. eCollection 2006.
Eccentric contractions produce a significant degree of inflammation and muscle injury that may increase the expression of myostatin. Due to its anti- oxidant and anti-flammatory effects, circulating 17-β estradiol (E2) may attenuate myostatin expression. Eight males and eight females performed 7 sets of 10 reps of eccentric contractions of the knee extensors at 150% 1-RM. Each female performed the eccentric exercise bout on a day that fell within her mid-luteal phase (d 21-23 of her 28-d cycle). Blood and muscle samples were obtained before and 6 and 24 h after exercise, while additional blood samples were obtained at 48 and 72 h after exercise. Serum E2 and myostatin LAP/propeptide (LAP/pro) levels were determined with ELISA, and myostatin mRNA expression determined using RT-PCR. Data were analyzed with two-way ANOVA and bivariate correlations (p < 0.05). Females had greater levels of serum E2 throughout the 72- h sampling period (p < 0.05). While males had greater body mass and fat-free mass, neither was correlated to the pre-exercise levels of myostatin mRNA and LAP/pro for either gender (p > 0.05). Compared to pre-exercise, males had significant increases (p < 0.05) in LAP/propetide and mRNA of 78% and 28%, respectively, at 24 h post-exercise, whereas females underwent respective decreases of 10% and 21%. E2 and LAP/propeptide were correlated at 6 h (r = -0.804, p = 0.016) and 24 h post- exercise (r = -0.841, p = 0.009) in males, whereas in females E2 levels were correlated to myostatin mRNA at 6 h (r =0.739, p = 0.036) and 24 h (r = 0.813, p = 0.014) post-exercise and LAP/propeptide at 6 h (r = 0.713, p = 0.047) and 24 h (r = 0.735, p = 0.038). In females, myostatin mRNA expression and serum LAP/propeptide levels do not appear to be significantly up-regulated following eccentric exercise, and may be due to higher levels of circulating E2. Key PointsThe pre-exercise levels of myostatin mRNA and propeptide were not significantly different between genders, and even though the total body mass and fat-free mass of males were significantly greater than females, neither was correlated to myostatin mRNA or LAP/propeptide.Myostatin mRNA expression in females is less than in males 24 h after a single bout of eccentric exercise.Myostatin LAP/propeptide levels in females are lower in females than in males 24 h after a single bout of eccentric exercise, thereby suggesting a gender-specific mechanism in which females may be less responsive to eccentric exercise than males.Myostatin mRNA expression in females is attenuated, possibly due to inhibition in myostatin signaling, and appears to be more related to the presence of a higher level of circulating E2 rather than body composition.Due to their higher level of E2, females seem to be less susceptible to the mechanism by which eccentric exercise apparently up-regulates myostatin mRNA expression in males.
离心收缩会产生显著的炎症和肌肉损伤程度，这可能会增加肌肉生长抑制素的表达。由于 17-β 雌二醇（E2）具有抗氧化和抗炎作用，循环中的 17-β 雌二醇（E2）可能会减弱肌肉生长抑制素的表达。8 名男性和 8 名女性进行了 7 组 10 次 150%1-RM 的离心收缩膝关节伸展运动。每位女性在其黄体中期（28 天周期的第 21-23 天）进行离心运动。在运动前、运动后 6 小时和 24 小时以及运动后 48 小时和 72 小时采集血液和肌肉样本。使用 ELISA 测定血清 E2 和肌肉生长抑制素 LAP/前肽（LAP/pro）水平，并用 RT-PCR 测定肌肉生长抑制素 mRNA 表达。使用双因素方差分析和双变量相关性（p < 0.05）进行数据分析。女性在整个 72 小时采样期间的血清 E2 水平均较高（p < 0.05）。虽然男性的体重和去脂体重较大，但两者均与男女的运动前肌肉生长抑制素 mRNA 和 LAP/pro 水平无关（p > 0.05）。与运动前相比，男性在运动后 24 小时时，LAP/propeptide 和 mRNA 分别显著增加了 78%和 28%（p < 0.05），而女性分别减少了 10%和 21%。男性在运动后 6 小时（r = -0.804，p = 0.016）和 24 小时（r = -0.841，p = 0.009）时，E2 和 LAP/propeptide 呈负相关，而女性在运动后 6 小时（r = 0.739，p = 0.036）和 24 小时（r = 0.813，p = 0.014）时，E2 水平与肌肉生长抑制素 mRNA 呈正相关，在运动后 6 小时（r = 0.713，p = 0.047）和 24 小时（r = 0.735，p = 0.038）时，E2 水平与 LAP/propeptide 呈正相关。女性在进行单次离心运动后，肌肉生长抑制素 mRNA 表达和血清 LAP/propeptide 水平似乎没有明显上调，这可能是由于循环 E2 水平较高所致。关键要点：男女之间的运动前肌肉生长抑制素 mRNA 和前肽水平没有显著差异，尽管男性的总体重和去脂体重明显大于女性，但两者均与肌肉生长抑制素 mRNA 或 LAP/propeptide 无关。女性在单次离心运动后 24 小时的肌肉生长抑制素 mRNA 表达低于男性。女性在单次离心运动后 24 小时的 LAP/propeptide 水平低于男性，这表明女性对离心运动的反应可能不如男性，存在性别特异性机制。女性的肌肉生长抑制素 mRNA 表达减弱，可能是由于肌肉生长抑制素信号的抑制，并且似乎与循环中较高水平的 E2 更相关，而不是身体成分。由于女性的 E2 水平较高，她们似乎对离心运动明显上调男性肌肉生长抑制素 mRNA 表达的机制不太敏感。
