INFLUENCE OF SEVERAL C<sub>19</sub>STEROIDS ON THE GROWTH OF INDIVIDUAL MUSCLES OF THE GUINEA PIG12

Kochakian, Charles D.; Tillotson, Carol

doi:10.1210/endo-60-5-607

Cited by 56 publications

(16 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Similar intermuscular differences in AR content have also been demonstrated in frog skeletal muscles (Dorlochter et al 1994). In fact, a very early study showed that the sensitivity of guinea-pig skeletal muscles to testosterone stimulation was greatest in the head and neck region and gradually decreased from head to hindquarters (Kochakian and Tillotson 1957). Hence, our results provide a molecular basis for the differences in androgen sensitivity among different muscle groups.…”

Section: Discussionsupporting

confidence: 84%

The expression of androgen receptors in human neck and limb muscles: effects of training and self-administration of androgenic-anabolic steroids

Kadi¹,

Bonnerud²,

Eriksson³

et al. 2000

Histochemistry and Cell Biology

132

View full text Add to dashboard Cite

The purpose of this study was to investigate the immunohistochemical expression of androgen receptors (AR) in human vastus lateralis and trapezius muscles and to determine whether long-term strength training and self-administration of androgenic-anabolic steroids are accompanied by changes in AR content. Biopsy samples were taken from eight high-level power-lifters (P), nine high-level power-lifters who used anabolic steroids (PAS) and six untrained subjects (U). Myonuclei and AR were visualised in cross-sections stained with the monoclonal antibody against AR and 4',6-diamidino-2-phenylindole. The proportion of AR-containing myonuclei per fibre cross-section was higher in the trapezius than in the vastus lateralis (P<0.05). In the trapezius, the proportion of AR-containing myonuclei was higher in P compared to U and in PAS compared to both P and U (P<0. 05). On the contrary, in the vastus lateralis, there were no differences in AR content between the three groups. Myonuclear number in both muscles was higher in P compared to U and in PAS compared to both P and U (P<0.05). In conclusion, AR content differs greatly between human neck and limb muscles. Moreover, the regulation of AR-containing myonuclei following training and self-administration of androgenic-anabolic steroids is muscle dependent.

show abstract

Section: Discussionsupporting

confidence: 84%

The expression of androgen receptors in human neck and limb muscles: effects of training and self-administration of androgenic-anabolic steroids

Kadi¹,

Bonnerud²,

Eriksson³

et al. 2000

Histochemistry and Cell Biology

132

View full text Add to dashboard Cite

show abstract

“…Aging has been associated with a decline in the size and number of muscle fibers (22), and testosterone has been shown to increase muscle mass (10). Grip strength was measured because animal studies have demonstrated that the primary muscle effects of androgens occur in the upper body (23,24). Consistent with previous work (11,13), the major finding in this study was an increase in strength as measured by grip strength.…”

Section: Discussionsupporting

confidence: 82%

Testosterone Replacement in Older Hypogonadal Men: A 12-Month Randomized Controlled Trial

Sih

Morley

Kaiser

et al. 1997

The Journal of Clinical Endocrinology &Amp; Metabolism

670

432

View full text Add to dashboard Cite

A decline in testicular function is recognized as a common occurrence in older men. However data are sparse regarding the effects of hypogonadism on age-associated physical and cognitive declines. This study was undertaken to examine the year-long effects of testosterone administration in this patient population.Fifteen hypogonadal men (mean age 68 Ϯ 6 yr) were randomly assigned to receive a placebo, and 17 hypogonadal men (mean age 65 Ϯ 7 yr) were randomly assigned to receive testosterone. Hypogonadism was defined as a bioavailable testosterone Ͻ60 ng/dL. The men received injections of placebo or 200 mg testosterone cypionate biweekly for 12 months. The main outcomes measured included grip strength, hemoglobin, prostate-specific antigen, leptin, and memory.Testosterone improved bilateral grip strength (P Ͻ 0.05 by ANOVA) and increased hemoglobin (P Ͻ 0.001 by ANOVA). The men assigned to testosterone had greater decreases in leptin than those assigned to the control group (mean Ϯ SEM: Ϫ2.0 Ϯ 0.9 ng/dL vs. 0.8 Ϯ 0.7 ng/dL; P Ͻ 0.02). There were no significant changes in prostatespecific antigen or memory. Three subjects receiving placebo and seven subjects receiving testosterone withdrew from the study. Three of those seven withdrew because of an abnormal elevation in hematocrit.Testosterone supplementation improved strength, increased hemoglobin, and lowered leptin levels in older hypogonadal men. Testosterone may have a role in the treatment of frailty in males with hypogonadism; however, older men receiving testosterone must be carefully monitored because of its potential risks. (J Clin Endocrinol 82: [1661][1662][1663][1664][1665][1666][1667] 1997) A DECLINE in testicular function with a consequent decline in testosterone and bioavailable testosterone is recognized as a common occurrence in older men (1-5). Although there is great interindividual variability in testosterone and bioavailable testosterone (BT) levels with advancing age, half of healthy men between the ages of 50 -70 yr will have a BT level below the lowest level seen in healthy men who are 20 -40 yr of age (6).Studies have suggested that androgens have many important physiological actions including effects on sexual function, muscle, body composition, bone, bone marrow, prostate, and the central nervous system (7-11). However, data are sparse regarding the effects of the age-associated decline in testosterone secretion on these target systems.Few studies have assessed the role of testosterone replacement in older hypogonadal men and whether putative improvements in strength, body composition, and bone will occur without significant risks in this patient population. In a 6-month cross-over trial of testosterone, Tenover (12) found no change in muscle strength, an increase in hematocrit and prostate-specific antigen (PSA), a decrease in total cholesterol, and an increase in weight and lean body mass without changes in percent body fat. Morley et al. (13) found an increase in right-hand grip strength, an increase in hematocrit, and a d...

show abstract

“…Con, Control group with vehicle; T, 100 nM testosterone; TϩFst ab, 100 nM testosterone plus 0.5 g/ml anti-Fst antibody; rFst, recombinant Fst protein (0.2 g/ml). Pioneering studies in the mid-20th century had suggested that testosterone increases muscle mass by promoting nitrogen retention (40). More recent studies using stable isotopes provided additional evidence that testosterone stimulates muscle protein synthesis and increases the efficiency of amino acid reuse by the skeletal muscle (7,10,12).…”

Section: Fig 6 Inhibition Of Testosterone Induction Of Myod and Mhcmentioning

confidence: 99%

Regulation of Myogenic Differentiation by Androgens: Cross Talk between Androgen Receptor/ β-Catenin and Follistatin/Transforming Growth Factor-β Signaling Pathways

et al. 2008

View full text Add to dashboard Cite

Androgens are important regulators of body composition and promote myogenic differentiation and inhibit adipogenesis of mesenchymal, multipotent cells. Here, we investigated the mechanisms by which androgens induce myogenic differentiation of mesenchymal multipotent cells. Incubation of mesenchymal multipotent C3H 10T1/2 cells with testosterone and dihydrotestosterone promoted nuclear translocation of androgen receptor (AR)/beta-catenin complex and physical interaction of AR, beta-catenin, and T-cell factor-4 (TCF-4). Inhibition of beta-catenin by small inhibitory RNAs significantly decreased testosterone-induced stimulation of myogenic differentiation. Overexpression of TCF-4, a molecule downstream of beta-catenin in Wnt signaling cascade, in C3H 10T1/2 cells significantly up-regulated expression of myoD and myosin heavy chain II proteins and of follistatin (Fst), which binds and antagonizes native ligands of the TGF-beta/Smad pathway. Gene array analysis of C3H 10T1/2 cells treated with testosterone revealed that testosterone up-regulated the expression of Fst and modified the expression of several signaling molecules involved in the TGF-beta/Smad pathway, including Smad7. Lowering of testosterone levels in mice by orchidectomy led to a significant decrease in Fst and Smad7 expression; conversely, testosterone supplementation in castrated mice up-regulated Fst and Smad7 mRNA expression in androgen-responsive levator ani muscle. Testosterone-induced up-regulation of MyoD and myosin heavy chain II proteins in C3H 10T1/2 cells was abolished in cells simultaneously treated with anti-Fst antibody, suggesting an essential role of Fst during testosterone regulation of myogenic differentiation. In conclusion, our data suggest the involvement of AR, beta-catenin, and TCF-4 pathway during androgen action to activate a number of Wnt target genes, including Fst, and cross communication with the Smad signaling pathway.

show abstract

INFLUENCE OF SEVERAL C₁₉STEROIDS ON THE GROWTH OF INDIVIDUAL MUSCLES OF THE GUINEA PIG12

Cited by 56 publications

References 0 publications

The expression of androgen receptors in human neck and limb muscles: effects of training and self-administration of androgenic-anabolic steroids

The expression of androgen receptors in human neck and limb muscles: effects of training and self-administration of androgenic-anabolic steroids

Testosterone Replacement in Older Hypogonadal Men: A 12-Month Randomized Controlled Trial

Regulation of Myogenic Differentiation by Androgens: Cross Talk between Androgen Receptor/ β-Catenin and Follistatin/Transforming Growth Factor-β Signaling Pathways

Contact Info

Product

Resources

About

INFLUENCE OF SEVERAL C19STEROIDS ON THE GROWTH OF INDIVIDUAL MUSCLES OF THE GUINEA PIG12

Cited by 56 publications

References 0 publications

The expression of androgen receptors in human neck and limb muscles: effects of training and self-administration of androgenic-anabolic steroids

The expression of androgen receptors in human neck and limb muscles: effects of training and self-administration of androgenic-anabolic steroids

Testosterone Replacement in Older Hypogonadal Men: A 12-Month Randomized Controlled Trial

Regulation of Myogenic Differentiation by Androgens: Cross Talk between Androgen Receptor/ β-Catenin and Follistatin/Transforming Growth Factor-β Signaling Pathways

Contact Info

Product

Resources

About

INFLUENCE OF SEVERAL C₁₉STEROIDS ON THE GROWTH OF INDIVIDUAL MUSCLES OF THE GUINEA PIG12