Estrogen Effects on Skeletal Muscle Insulin-Like Growth Factor–1 and Myostatin in Ovariectomized Rats

Abstract

Previous work showed that estrogen replacement attenuates muscle growth in immature rats. The present study examined muscle insulin-like growth factor-1 (IGF-1) and myostatin expression to determine whether these growth regulators might be involved in mediating estrogen's effects on muscle growth. IGF-1 and myostatin message and protein expression in selected skeletal muscles from 7-week-old sham-ovariectomized (SHAM) and ovariectomized rats that received continuous estrogen (OVX/E2) or solvent vehicle (OVX/CO) from an implant for 1 week or 5 weeks was measured. In the 1-week study, ovariectomy increased IGF-1 mRNA expression in fast extensor digitorum longus and gastrocnemius muscles; the increase was reversed by estrogen replacement. A similar trend was observed in the slow soleus muscle, although the change was not statistically significant. In contrast to mRNA, muscle IGF-1 protein expression was not different between SHAM and OVX/ CO animals in the 1-week study. One week of estrogen replacement significantly decreased IGF-1 protein level in all muscles examined. Myostatin mRNA expression was not different among the 1-week treatment groups. One week of estrogen replacement significantly increased myostatin protein in the slow soleus muscle but not the fast extensor digitorum longus and gastrocnemius muscles. There was no treatment effect on IGF-1 and myostatin expression in the 5-week study; this finding suggested a transient estrogen effect or upregulation of a compensatory mechanism to counteract the estrogen effect observed at the earlier time point. This investigation is the first to explore ovariectomy and estrogen effects on skeletal muscle IGF-1 and myostatin expression. Results suggest that reduced levels of muscle IGF-1 protein may mediate estrogen's effect on growth in immature, ovariectomized rats. Increased levels of muscle myostatin protein may also have a role in mediating estrogen's effects on growth in slow but not fast skeletal muscle.

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).…”

Expression profiling of skeletal muscle in young bulls treated with steroidal growth promoters

“…Estrogen replacement in immature ovariectomized rats was shown to reduce body weight, muscle growth, and muscle fiber size (42). More specifically, 1-wk estrogen replacement significantly reduced expression of IGF-1 mRNA and increased protein levels of myostatin (75). Therefore, IGF-1 and myostatin pathways might represent a first level of interaction between Dex and Estr, with the two hormones having opposite effects on such signaling pathways.…”

Effects of sex steroids on expression of myostatin in rare minnow, Gobiocypris rarus

“…Here, we show that EE2 can increase expression of GrMSTN, which was negatively correlated with body growth. Similarly, short time administration of estrogen increases MSTN expression in rat (Tsai et al, 2007). Administration of androgen had controversy effects on MSTN expression in human and testosterone might or might not influence MSTN expression (Kvorning et al, 2007;Lakshman et al, 2009;Lewis et al, 2007).…”

“…Androgen can affect GH expression in the goldfish (Carassius auratus) pituitary (Huggard et al, 1996) and IGFI level in coho salmon (Larsen, et al, 2004). Estradiol can alter plasma GH level in rainbow trout (Holloway and Leatherland, 1997), GH and IGFI expressions in rat (Tsai et al, 2007) and tilapia (Shved, et al, 2008;2009). GH can affect MSTN expression such as in rainbow trout (Biga et al, 2004) and coho salmon .…”

“…Estrogen replacement attenuated muscle growth of young ovariectomized rat (Rattus rattus) (Piccone et al, 2005). Transient (1 week) usage of estrogen decreased insulin-like growth factor-1 (IGF1) and increased MSTN expression, however long time (5 week) administration of estrogen did not apparently influence the expression of IGF1 and MSTN in rat (Tsai et al, 2007).…”