Effects of Gonadectomy and Estrogen Administration on Rat Skeletal Muscle

Kobori, Masuko; Yamamuro, Takao

doi:10.1097/00003086-198906000-00045

Cited by 50 publications

(44 citation statements)

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“…However, E2 caused a significant decrease in swimbladder mass and a reduction in the sarcoplasm area/myofibril area ratio, which possibly resulted from a slight simultaneous decrease in sarcoplasm area and an increase in myofibril area, both features characteristic of females. These effects of E2 implantation were similar to those induced by the long-term castration and resemble the inhibitory effect in the development of type IIA skeletal fibers (characteristic of swimbladder muscles; Fine and Pennypacker, 1988) induced by E2 in rats (Koboni and Yamamuro, 1989;Suzuki and Yamamuro, 1985). Walsh et al (1995) cited unpublished results by Mommsen and Bass in which treatment of adult type I males of P. notatus with E2 for a few weeks resulted in significant decreases in the overall mass of sonic muscle.…”

Section: Intact (Int) Sham-operated (Sham) Castrated (Cast) Castrasupporting

confidence: 62%

Hormonal control of swimbladder sonic muscle dimorphism in the Lusitanian toadfish Halobatrachus didactylus

Modesto

Canário

2003

Journal of Experimental Biology

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SUMMARY The swimbladder and associated sonic muscle of the Lusitanian toadfish Halobatrachus didactylus increase in size throughout life and are,respectively, 25% and 30% larger in type I (nest-holder) males than females,which may generate sexual differences in sound production. Sexual dimorphism in swimbladder is also evident in the morphological features of sonic muscle fibers. During the breeding season, type I males have smaller myofibril contracting zones surrounded by larger sarcoplasm areas compared with females,possibly an adaptation to speed and fatigue resistance for the production of long mating calls. Type II (floater) males show characteristics that are intermediate, but statistically not significantly different, between type I males and females. Six weeks after castration and androgen (testosterone and 11-ketotestosterone) replacement in type I and type II males there were no alterations either in swimbladder mass or fiber morphology. However,17β-estradiol induced a significant decrease in swimbladder mass and sarcoplasm area/myofibril area ratio. Six months after castration there was a clear reduction in the seasonal swimbladder hypertrophy in males and induction of sonic fiber morphological characteristics that resemble those occurring in females (low sarcoplasm area/myofibril area ratio). These results suggest that testicular factors are required to initiate sonic muscle hypertrophy and type I sonic fiber phenotype in H. didactylus, but a specific involvement of androgens has not been completely clarified.

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Section: Intact (Int) Sham-operated (Sham) Castrated (Cast) Castrasupporting

confidence: 62%

Hormonal control of swimbladder sonic muscle dimorphism in the Lusitanian toadfish Halobatrachus didactylus

Modesto

Canário

2003

Journal of Experimental Biology

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“…Women after menopause have decreased lean body mass, which can be reversed by estrogen replacement therapy (Sorensen et al 2001). In animals, estrogen has been shown to regulate skeletal muscle mass in developing livestock, rats, and mice (Trenkle 1976, Kobori & Yamamuro 1989, McCormick et al 2004, Moran et al 2007. Furthermore, ovariectomy decreases rat skeletal muscle mass recovery, and estrogen replacement benefits atrophied muscle mass recovery (Brown et al 2005, Sitnick et al 2006.…”

Section: Introductionmentioning

confidence: 99%

Stimulation of both estrogen and androgen receptors maintains skeletal muscle mass in gonadectomized male mice but mainly via different pathways

Svensson¹,

Movérare‐Skrtic²,

Windahl³

et al. 2010

Journal of Molecular Endocrinology

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Testosterone is a major regulator of muscle mass. Little is known whether this is due to a direct stimulation of the androgen receptor (AR) or mediated by aromatization of testosterone to estradiol (E 2 ), the ligand for the estrogen receptors (ERs), in peripheral tissues. In this study, we differentiated between the effects mediated by AR and ER by treating orchidectomized (orx) male mice for 5 weeks with E 2 or the non-aromatizable androgen dihydrotestosterone (DHT). Both E 2 and DHT increased muscle weight and lean mass, although the effect was less marked after E 2 treatment. Studies of underlying mechanisms were performed using gene transcript profiling (microarray and real-time PCR) in skeletal muscle, and they demonstrated that E 2 regulated 51 genes and DHT regulated 187 genes, with 13 genes (Z25% of E 2 -regulated genes) being regulated by both treatments. Both E 2 and DHT altered the expression of Fbxo32, a gene involved in skeletal muscle atrophy, affected the IGF1 system, and regulated genes involved in angiogenesis and the glutathione metabolic process. Only E 2 affected genes that regulate intermediary glucose and lipid metabolism, and only DHT increased the expression of genes involved in synaptic transmission and heme and polyamine biosynthesis. In summary, ER activation by E 2 treatment maintains skeletal muscle mass after orx. This effect is less marked than that of AR activation by DHT treatment, which completely prevented the effect of orx on muscle mass and was partly, but not fully, mediated via alternative pathways.

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“…Testosterone has been shown to induce muscle hypertrophy and lead to increases in voluntary strength (50). Estrogen has been shown to stimulate muscle repair and regenerative processes (11), although the extent and direction of the muscle response does seem contingent on species and circumstance (23,28,33).…”

mentioning

confidence: 99%

Chronic exposure to anabolic steroids induces the muscle expression of oxytocin and a more than fiftyfold increase in circulating oxytocin in cattle

Jager

Hudson

Reverter

et al. 2011

Physiological Genomics

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Chronic exposure to anabolic steroids induces the muscle expression of oxytocin and a more than fiftyfold increase in circulating oxytocin in cattle. Physiol Genomics 43: 467-478, 2011. First published February 15, 2011 doi:10.1152/physiolgenomics.00226.2010.-Molecular mechanisms in skeletal muscle associated with anabolic steroid treatment of cattle are unclear and we aimed to characterize transcriptional changes. Cattle were chronically exposed (68 Ϯ 20 days) to a steroid hormone implant containing 200 mg trenbolone acetate and 20 mg estradiol (Revalor-H). Biopsy samples from 48 cattle (half treated) from longissimus dorsi (LD) muscle under local anesthesia were collected. Gene expression levels were profiled by microarray, covering 16,944 unique bovine genes: 121 genes were differentially expressed (DE) due to the implant (99.99% posterior probability of not being false positives). Among DE genes, a decrease in expression of a number of fat metabolism-associated genes, likely reflecting the lipid storage activity of intramuscular adipocytes, was observed. The expression of IGF1 and genes related to the extracellular matrix, slow twitch fibers, and cell cycle (including SOX8, a satellite cell marker) was increased in the treated muscle. Unexpectedly, a very large 21-(microarray) to 97 (real time quantitative PCR)-fold higher expression of the mRNA encoding the neuropeptide hormone oxytocin was observed in treated muscle. We also observed an ϳ50-fold higher level of circulating oxytocin in the plasma of treated animals at the time of biopsy. Using a coexpression network strategy OXTR was identified as more likely than IGF1R to be a major mediator of the muscle response to Revalor-H. A re-investigation of in vivo cattle LD muscle samples during early to mid-fetal development identified a Ͼ128-fold increased expression of OXT, coincident with myofiber differentiation and fusion. We propose that oxytocin may be involved in mediating the anabolic effects of Revalor-H treatment.

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Effects of Gonadectomy and Estrogen Administration on Rat Skeletal Muscle

Cited by 50 publications

References 0 publications

Hormonal control of swimbladder sonic muscle dimorphism in the Lusitanian toadfish Halobatrachus didactylus

Hormonal control of swimbladder sonic muscle dimorphism in the Lusitanian toadfish Halobatrachus didactylus

Stimulation of both estrogen and androgen receptors maintains skeletal muscle mass in gonadectomized male mice but mainly via different pathways

Chronic exposure to anabolic steroids induces the muscle expression of oxytocin and a more than fiftyfold increase in circulating oxytocin in cattle

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