Effects of ovariectomy and estrogen on skeletal muscle function in growing rats

Abstract

This study examined the effect of estrogen replacement on soleus muscle size and contractile function in ovariectomized rats during physiological growth. Seven week old female Sprague-Dawley rats were assigned to one of three treatment groups: (1) control animals (SHAM), (2) ovariectomized animals without estrogen replacement (OVX/CO), and (3) ovariectomized animals with 17 beta-estradiol replacement (OVX/E2). OVX/CO and OVX/E2 animals were pair-fed to SHAM animals to rule out the potentially confounding effect of differences in food intake. Rats were sacrificed 4 weeks after surgery and the soleus muscle was removed for analysis. Estrogen replacement reduced body weight, relative body weight gain, and soleus muscle fiber size despite all groups having a similar food intake. Ovariectomy alone had no effect on any of these parameters suggesting that estrogen may inhibit skeletal muscle growth when it is the only ovarian hormone present. Neither ovariectomy nor estrogen replacement affected maximal specific isometric force. Estrogen replacement increased half relaxation time. Ovariectomy resulted in a reduction in time to peak tension that was reversed with estrogen replacement. This reduction was not accompanied by a change in myosin heavy chain composition implying that calcium handling may have been altered. Results from this study suggest that estrogen affects skeletal muscle growth and twitch kinetics.

Muscle function in monozygotic female twin pairs discordant for hormone replacement therapy

“…Contrary to these results, an increase in twitch 70 % decay time 27 and half-relaxation time in rats having greater serum E2 concentration have been reported 35 .…”

17β-Estradiol Represses Myogenic Differentiation by Increasing Ubiquitin-specific Peptidase 19 through Estrogen Receptor α

“…ments were performed in ovariectomized young female mice. E2 replacement was found to reduce soleus muscle fiber size in 7-week-old ovariectomized female rats (34,35). Furthermore, estrogen injection was found to reduce soleus and gastrocnemius muscle weights of both sexes (36).…”

Effects of Exposure Period and Dose of Diethylstilbestrol on Pregnancy in Rats

“…The strong estrogenicity of DES reduces food consumption in bred rats in the same way that  E 2 reduces food consumption [3]. In turn, estrogen replacement reduces BW in growing rats [15], although the effect of estrogen on fetal growth is unknown. Therefore, the decreased BWs of the pups may result from reduced food consumption of dams or the strong estrogenicity of DES.…”