1. Testosterone and trenbolone enanthate increase mature myostatin protein expression despite increasing skeletal muscle hypertrophy and satellite cell number in rodent muscle.
- Author
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Dalbo VJ, Roberts MD, Mobley CB, Ballmann C, Kephart WC, Fox CD, Santucci VA, Conover CF, Beggs LA, Balaez A, Hoerr FJ, Yarrow JF, Borst SE, and Beck DT
- Subjects
- Activin Receptors, Type II metabolism, Anabolic Agents administration & dosage, Androgens administration & dosage, Animals, Cell Count, Cell Differentiation drug effects, Cell Enlargement drug effects, Male, Muscle, Skeletal growth & development, Muscle, Skeletal metabolism, Orchiectomy adverse effects, Rats, Rats, Inbred F344, Satellite Cells, Skeletal Muscle cytology, Smad2 Protein metabolism, Smad3 Protein metabolism, Testis surgery, Testosterone administration & dosage, Trenbolone Acetate administration & dosage, Anabolic Agents pharmacology, Androgens pharmacology, Muscle, Skeletal drug effects, Myostatin metabolism, Satellite Cells, Skeletal Muscle drug effects, Testosterone pharmacology, Trenbolone Acetate pharmacology
- Abstract
The androgen-induced alterations in adult rodent skeletal muscle fibre cross-sectional area (fCSA), satellite cell content and myostatin (Mstn) were examined in 10-month-old Fisher 344 rats (n = 41) assigned to Sham surgery, orchiectomy (ORX), ORX + testosterone (TEST; 7.0 mg week
-1 ) or ORX + trenbolone (TREN; 1.0 mg week-1 ). After 29 days, animals were euthanised and the levator ani/bulbocavernosus (LABC) muscle complex was harvested for analyses. LABC muscle fCSA was 102% and 94% higher in ORX + TEST and ORX + TREN compared to ORX (p < .001). ORX + TEST and ORX + TREN increased satellite cell numbers by 181% and 178% compared to ORX, respectively (p < .01), with no differences between conditions for myonuclear number per muscle fibre (p = .948). Mstn protein was increased 159% and 169% in the ORX + TEST and ORX + TREN compared to ORX (p < .01). pan-SMAD2/3 protein was ~30-50% greater in ORX compared to SHAM (p = .006), ORX + TEST (p = .037) and ORX + TREN (p = .043), although there were no between-treatment effects regarding phosphorylated SMAD2/3. Mstn, ActrIIb and Mighty mRNAs were lower in ORX, ORX + TEST and ORX + TREN compared to SHAM (p < .05). Testosterone and trenbolone administration increased muscle fCSA and satellite cell number without increasing myonuclei number, and increased Mstn protein levels. Several genes and signalling proteins related to myostatin signalling were differentially regulated by ORX or androgen therapy., (© 2016 Blackwell Verlag GmbH.)- Published
- 2017
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