Estrogen replacement improves skeletal muscle performance by increasing parvalbumin levels in ovariectomized rats

Muscle weakness is common during menopause. Effective estrogen replacement was hypothesized to prevent sarcopenia. This study aimed to investigate the estrogen level, estrogen receptors (α and β) immunoreactivities, muscle mass and functions, and parvalbumin (PV) levels in the extensor digitorum longus (EDL) and the gastrocnemius muscles of ovariectomized rats. Adult female Wistar rats (12 weeks old) were divided into five groups: sham-operated (SHAM), and ovariectomized (E0) groups that received 10 weeks of estrogen replacements of 0 μg/kg (E0), 10 μg/kg (E10), 20 μg/kg (E20) and 40 μg/kg (E40). The estrogen levels, ER α and ER β immunoreactivities, muscle fiber sizes and contractivities and the PV levels were reduced in the E0 group, but increased in all the estrogen replacement groups in both muscles. This study indicated that the reduction of estrogen levels led to a decrease of both ER α and ER β resulting in a decline in muscle mass and PV levels. The decrease of PV levels affected muscle performance, whereas estrogen replacement increased both the ER α and ER β. The increase in the PV levels may result in an improvement of muscle performance. This may explain one mechanism of estrogen on muscle mass and strength in estrogen dependent sarcopenia.