Bombardier E, Vigna C, Iqbal S, Tiidus P M, Tupling A R
Department of Kinesiology, University of Waterloo, Waterloo, ON, Canada N2L 3G1.
J Appl Physiol (1985). 2009 Jun;106(6):2009-15. doi: 10.1152/japplphysiol.91573.2008. Epub 2009 Apr 9.
This study examined the influence of the ovarian sex hormones, estrogen and progesterone, on the fiber-type-specific response of the inducible 70-kDa heat shock protein (HSP70) to damaging exercise in rat soleus. Ovariectomized female rats were divided into three treatment groups (n = 16 per group): sham (S), progesterone (P; 25 mg pellet), and estrogen (E; 0.25 mg pellet). Each treatment group was divided into control and exercised groups. After 8 days of sham or hormone treatment, animals ran downhill intermittently for 90 min (17 m/min, -13.5 degrees grade) on a treadmill, and soleus muscles were removed 24 h postexercise. HSP70 expression was assessed in whole muscle homogenates by Western blotting and in individual muscle fiber types by immunohistochemical analysis of serial cross sections of soleus samples. Comparisons between control groups showed that HSP70 expression in soleus was increased (P < 0.05) in E compared with both S and P. No difference (P > 0.05) was observed between S and P. Following downhill running, HSP70 content in soleus was increased (P < 0.05) compared with control in S and P, but not (P > 0.05) in E. As a result, soleus HSP70 content following downhill running was not different (P > 0.05) between any of the treatment groups. Under all conditions, HSP70 content was higher in type I vs. type II fibers, and the effects of both estrogen and exercise on HSP70 expression in soleus were also more pronounced in type I vs. type II fibers. These results demonstrate that 1) estrogen regulates HSP70 expression in skeletal muscle, increasing basal HSP70 expression and preventing further increases in HSP70 in response to exercise; 2) progesterone is not involved in the regulation of HSP70 expression in skeletal muscle; and 3) the effects of estrogen and exercise on HSP70 expression in skeletal muscle are fiber type specific.
本研究检测了卵巢性激素雌激素和孕酮对诱导型70 kDa热休克蛋白（HSP70）在大鼠比目鱼肌中对损伤性运动的纤维类型特异性反应的影响。将去卵巢的雌性大鼠分为三个治疗组（每组n = 16）：假手术组（S）、孕酮组（P；25 mg药丸）和雌激素组（E；0.25 mg药丸）。每个治疗组再分为对照组和运动组。在进行假手术或激素治疗8天后，动物在跑步机上间歇性下坡跑90分钟（17米/分钟，-13.5度坡度），运动后24小时取出比目鱼肌。通过蛋白质免疫印迹法在全肌肉匀浆中评估HSP70表达，并通过对比目鱼肌样本连续横切片的免疫组织化学分析在单个肌纤维类型中评估HSP70表达。对照组之间的比较表明，与S组和P组相比，E组比目鱼肌中的HSP70表达增加（P < 0.05）。S组和P组之间未观察到差异（P > 0.05）。下坡跑后，与S组和P组的对照组相比，比目鱼肌中的HSP70含量增加（P < 0.05），但E组未增加（P > 0.05）。因此，下坡跑后任何治疗组之间比目鱼肌中的HSP70含量均无差异（P > 0.05）。在所有条件下，I型纤维中的HSP70含量高于II型纤维，并且雌激素和运动对比目鱼肌中HSP70表达的影响在I型纤维中也比II型纤维更明显。这些结果表明：1）雌激素调节骨骼肌中的HSP70表达，增加基础HSP70表达并阻止HSP70在运动反应中的进一步增加；2）孕酮不参与骨骼肌中HSP70表达的调节；3）雌激素和运动对骨骼肌中HSP70表达的影响具有纤维类型特异性。
