Citation

Larson AA, Baumann CW, Kyba M, Lowe DA. Exp. Physiol. 2020; ePub(ePub): ePub.

Copyright

(Copyright © 2020, The Physiological Society, Publisher John Wiley and Sons)

DOI

10.1113/EP088827

PMID

32851730

Abstract

NEW FINDINGS: What is the central question of this study? Estradiol (E2 ) plays an important role in regulating skeletal muscle strength in females. Here, we asked to what extent E2 deficiency affects recovery of strength and satellite cell number when muscle is challenged by multiple injuries. What is the main finding and its importance? E2 deficiency impairs the adaptive potential of skeletal muscle following repeated injuries, as measured by muscle mass and strength. The impairment is likely multifactorial with our data indicating that one mechanism is reduction in satellite cell number. Our findings have implications for aging, hormone replacement and regenerative medicine in regards to maintaining satellite cell number and ultimately the preservation of skeletal muscle's adaptive potential.

ABSTRACT: Estradiol effects on skeletal muscle are multifactorial including the preservation of mass, contractility and regeneration. Here, we aimed to determine the extent to which estradiol deficiency affects strength recovery when muscle is challenged by multiple BaCl2 -induced injuries and to assess how satellite cell number is influenced by the combination of estradiol deficiency and repetitive skeletal muscle injuries. A longitudinal study was designed, using an in vivo anesthetized mouse approach to precisely and repeatedly measure maximal isometric torque, coupled with endpoint fluorescent-activated cell sorting to quantify satellite cells. Isometric torque and strength gains were lower in ovariectomized mice at several time points after the injuries compared to those treated with 17β-estradiol. Satellite cell number was 41-43% lower in placebo- than estradiol-treated ovariectomized mice, regardless of injury status or number of injuries. Together, these results indicate that the loss of estradiol blunts adaptive strength gains and that the number of satellite cells likely contributes to the impairment. This article is protected by copyright. All rights reserved.

Language: en

Keywords

recovery; estrogen; muscle stem cells; ovariectomy; skeletal muscle