Estrogens And Muscle

J Physiol Sci. 2006 Oct 21;

Estrogen Administration Attenuates Immobilization-Induced Skeletal Muscle Atrophy in Male Rats.

Sugiura T, Ito N, Goto K, Naito H, Yoshioka T, Powers SK.

Department of Exercise and Health Sciences, Faculty of Education, Yamaguchi University, Yamaguchi, 753-8513 Japan.

We tested the hypothesis that estrogen administration would retard immobilization-induced muscle atrophy in adult male rats. 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 using a plaster cast. Following 10 days of immobilzation, both the atrophic and the contralateral soleus muscles were removed and analyzed to determine the level of muscle atrophy along with measurement of the protein levels of CuZn-superoxide dismutase (CuZnSOD), 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 protein levels of HSP72 in the immobilized soleus muscle. These results support the postulate that estrogen attenuates the rate of disuse muscle atrophy, due in part, to reductions in immobilization-induced calcium-activated protease levels.

J Appl Physiol. 2006 Jun;100(6):2012-23.

Estrogen status and skeletal muscle recovery from disuse atrophy.

McClung JM, Davis JM, Wilson MA, Goldsmith EC, Carson JA.

Integrative Muscle Biology Laboratory, Division of Applied Physiology, University of South Carolina, Department of Exercise Science, 1300 Wheat St., Columbia, SC 29208, USA.

Although estrogen loss can alter skeletal muscle recovery from disuse, the specific components of muscle regrowth that are estrogen sensitive have not been described. The primary purpose of this study was to determine the components of skeletal muscle mass recovery that are biological targets of estrogen. Intact, ovariectomized (OVX), and ovariectomized with 17beta-estradiol replacement (OVX+E2) female rats were subjected to hindlimb suspension for 10 days and then returned to normal cage ambulation for the duration of recovery. Soleus muscle mass returned to control levels by day 7 of recovery in the intact animals, whereas OVX soleus mass did not recover until day 14. Intact rats recovered soleus mean myofiber cross-sectional area (CSA) by day 14 of recovery, whereas the OVX soleus remained decreased (42%) at day 14. OVX mean fiber CSA did return to control levels by day 28 of recovery. The OVX+E2 treatment group recovered mean CSA at day 14, as in the intact animals. Myofibers demonstrating central nuclei were increased at day 14 in the OVX group, but not in intact or OVX+E2 animals. The percent noncontractile tissue was also increased 29% in OVX muscle at day 14, but not in either intact or OVX+E2 groups. In addition, collagen 1a mRNA was increased 45% in OVX muscle at day 14 of recovery. These results suggest that myofiber growth, myofiber regeneration, and extracellular matrix remodeling are estrogen-sensitive components of soleus muscle mass recovery from disuse atrophy.

Histochem Cell Biol. 2006 Aug 3;

Evidence for estrogen receptor alpha and beta expression in skeletal muscle of pigs.

Kalbe C, Mau M, Wollenhaupt K, Rehfeldt C.

Research Institute for the Biology of Farm Animals (FBN), Muscle Biology and Growth Research Unit, Wilhelm-Stahl-Allee 2, 18196, Dummerstorf, Germany.

Recent research suggests that estrogen receptors (ERs) are of significance in skeletal muscle function. The aim of the present study was to investigate, whether ERalpha and ERbeta are expressed in different porcine skeletal muscles and in satellite cells derived from semimembranosus muscle (SM) at the protein and mRNA level. Immunohistochemistry demonstrated positive staining for ERalpha in the nuclei of skeletal muscle cells, while the ERbeta stain showed positive signals in nuclei and cytoplasm of skeletal myofibers and myoblasts derived from satellite cells. Additionally, a weak expression of both ER subtypes was seen in skeletal muscle tissue and SM satellite cells with Western blot analysis. A clear expression of the ERalpha mRNA and a weak expression of the ERbeta mRNA was seen in skeletal muscle tissue and SM satellite cell cultures, as determined by reverse transcription (RT)-PCR. The present study shows for the first time that both ERalpha and ERbeta are expressed in porcine skeletal muscle, which, consequently, could be considered as a target tissue for estrogens or estrogen-like compounds. However, more detailed studies on the functional impact of both receptor subtypes in skeletal muscle are necessary. The porcine SM satellite cell culture provides a suitable in vitro model to investigate estrogenic effects on pig skeletal muscle.

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