Estrogen receptor [alpha] and [beta] knock-out effects on skeletal muscle in mature female and male mice, and aromatase knock-out effects on skeletal muscle in mature male mice

Abstract

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] Estrogen regulates skeletal muscle mass and function in female. Estrogen may influence skeletal muscle mass and function during development in males as estrogen receptors (ER) have been identified in both female and male skeletal muscle. Whether estrogen exerts its effects on skeletal muscle through estrogen receptor alpha (ER[alpha]) or beta (ER[beta]) or directly during development is unclear. The main purpose of this study was to determine ER knock-out effects on muscle mass and contractile function in muscle with different fiber types, in mature female and male mice that were either ER[alpha] knock out (ER-/-) or ER[beta]-/- with corresponding wild type (WT) groups as controls. Loss of ER[alpha] results in increased Gast and TA muscle in female mice whereas the muscle functions are not affected, and ER[alpha] also influences female Plan muscle function. In contrast, ER[beta] might not have effects on skeletal muscle in female mice. ER-/- and Ar-/- result in decreased Gast and TA muscle in male mice, suggesting that estrogen/ER[alpha] signaling might directly regulate male muscle growth, whereas the muscle function are not affected. In contrast, ER[beta] might not have any effects on skeletal muscle in male mice.