Effects of castration and androgen treatment on androgen-receptor levels in rat skeletal muscles

1999 ◽  
Vol 87 (6) ◽  
pp. 2016-2019 ◽  
Author(s):  
Jose Antonio ◽  
Jean D. Wilson ◽  
Fredrick W. George
Keyword(s):  
Skeletal Muscle ◽  
Androgen Receptor ◽  
Muscle Mass ◽  
Skeletal Muscles ◽  
Skeletal Muscle Mass ◽  
Levator Ani ◽  
Male Rats ◽  
Levator Ani Muscle ◽  
Plantaris Muscle ◽  
Androgen Treatment

The effects of castration and dihydrotestosterone (DHT) treatment on levels of skeletal muscle androgen receptor (AR) were examined in three groups of adult male rats: 1) intact normal rats, 2) rats castrated at 16 wk of age, and 3) rats castrated at 16 wk of age and given DHT for 1 wk starting at week 17. All animals were killed at 18 wk of age. Castration caused a decrease ( P< 0.05) in the weights of the levator ani and bulbocavernosus muscles. The administration of DHT to the castrated rats increased ( P < 0.05) the weights of the levator ani and bulbocavernosus muscles. Castration caused a significant downregulation of AR levels in the bulbocavernosus ( P< 0.05) but had no significant effect on AR levels in the levator ani muscle. DHT administration to the castrated group upregulated AR levels in the bulbocavernosus and levator ani muscles. The plantaris muscle did not significantly ( P > 0.05) change for any of the treatments. These findings suggest that the effects of castration and androgen replacement differentially affect skeletal muscle mass and AR levels.

scholarly journals Enobosarm (GTx-024) Modulates Adult Skeletal Muscle Mass Independently of the Androgen Receptor in the Satellite Cell Lineage

Endocrinology ◽  
2015 ◽  
Vol 156 (12) ◽  
pp. 4522-4533 ◽  
Author(s):  
Vanessa Dubois ◽  
Ioannis Simitsidellis ◽  
Michaël R. Laurent ◽  
Ferran Jardi ◽  
Philippa T. K. Saunders ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Androgen Receptor ◽  
Satellite Cell ◽  
Muscle Mass ◽  
Skeletal Muscle Mass ◽  
Cell Lineage ◽  
Levator Ani ◽  
Levator Ani Muscle ◽  
Adult Skeletal Muscle ◽  
Receptor Modulator

Androgens increase skeletal muscle mass, but their clinical use is hampered by a lack of tissue selectivity and subsequent side effects. Selective androgen receptor modulators elicit muscle-anabolic effects while only sparingly affecting reproductive tissues. The selective androgen receptor modulator, GTx-024 (enobosarm), is being investigated for cancer cachexia, sarcopenia, and muscle wasting diseases. Here we investigate the role of muscle androgen receptor (AR) in the anabolic effect of GTx-024. In mice lacking AR in the satellite cell lineage (satARKO), the weight of the androgen-sensitive levator ani muscle was lower but was decreased further upon orchidectomy. GTx-024 was as effective as DHT in restoring levator ani weights to sham levels. Expression of the muscle-specific, androgen-responsive genes S-adenosylmethionine decarboxylase and myostatin was decreased by orchidectomy and restored by GTx-024 and DHT in control mice, whereas the expression was low and unaffected by androgen status in satARKO. In contrast, insulin-like growth factor 1Ea expression was not different between satARKO and control muscle, decreased upon castration, and was restored by DHT and GTx-024 in both genotypes. These data indicate that GTx-024 does not selectively modulate AR in the satellite cell lineage and that cells outside this lineage remain androgen responsive in satARKO muscle. Indeed, residual AR-positive cells were present in satARKO muscle, coexpressing the fibroblast-lineage marker vimentin. AR positive, muscle-resident fibroblasts could therefore be involved in the indirect effects of androgens on muscle. In conclusion, both DHT and GTx-024 target AR pathways in the satellite cell lineage, but cells outside this lineage also contribute to the anabolic effects of androgens.

scholarly journals Selective Androgen Receptor Modulator Treatment Improves Muscle Strength and Body Composition and Prevents Bone Loss in Orchidectomized Rats

Endocrinology ◽  
2005 ◽  
Vol 146 (11) ◽  
pp. 4887-4897 ◽  
Author(s):  
Wenqing Gao ◽  
Peter J. Reiser ◽  
Christopher C. Coss ◽  
Mitch A. Phelps ◽  
Jeffrey D. Kearbey ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Androgen Receptor ◽  
Muscle Mass ◽  
Male Rats ◽  
Levator Ani Muscle ◽  
Dependent Manner ◽  
Agonist Activity ◽  
Mineral Density ◽  
Selective Androgen Receptor Modulator ◽  
Receptor Modulator

The partial agonist activity of a selective androgen receptor modulator (SARM) in the prostate was demonstrated in orchidectomized rats. In the current study, we characterized the full agonist activity of S-3-(4-acetylamino-phenoxy)-2-hydroxy-2-methyl-N-(4-nitro-3-trifluoromethyl-phenyl)-propionamide (a structurally related SARM referred to in other publications and hereafter as S-4) in skeletal muscle, bone, and pituitary of castrated male rats. Twelve weeks after castration, animals were treated with S-4 (3 or 10 mg/kg), dihydrotestosterone (DHT) (3 mg/kg), or vehicle for 8 wk. S-4 (3 and 10 mg/kg) restored soleus muscle mass and strength and levator ani muscle mass to that seen in intact animals. Similar changes were also observed in DHT-treated (3 mg/kg) animals. Compared with the anabolic effects observed in muscle, DHT (3 mg/kg) stimulated prostate and seminal vesicle weights moire than 2-fold greater than that observed in intact controls, whereas S-4 (3 mg/kg) returned these androgenic organs to only 16 and 17%, respectively, of the control levels. S-4 (3 and 10 mg/kg) and DHT (3 mg/kg) restored castration-induced loss in lean body mass. Furthermore, S-4 treatment caused a significantly larger increase in total body bone mineral density than DHT. S-4 (3 and 10 mg/kg) also demonstrated agonist activity in the pituitary and significantly decreased plasma LH and FSH levels in castrated animals in a dose-dependent manner. In summary, the strong anabolic effects of S-4 in skeletal muscle, bone, and pituitary were achieved with minimal pharmacologic effect in the prostate. The tissue-selective pharmacologic activity of SARMs provides obvious advantages over steroidal androgen therapy and demonstrates the promising therapeutic utility that this new class of drugs may hold.

scholarly journals Preclinical Characterization of a (S)-N-(4-Cyano-3-Trifluoromethyl-Phenyl)-3-(3-Fluoro, 4-Chlorophenoxy)-2-Hydroxy-2-Methyl-Propanamide: A Selective Androgen Receptor Modulator for Hormonal Male Contraception

Endocrinology ◽  
2008 ◽  
Vol 150 (1) ◽  
pp. 385-395 ◽  
Author(s):  
Amanda Jones ◽  
Jiyun Chen ◽  
Dong Jin Hwang ◽  
Duane D. Miller ◽  
James T. Dalton
Keyword(s):  
Androgen Receptor ◽  
Levator Ani ◽  
Male Rats ◽  
Male Contraception ◽  
Levator Ani Muscle ◽  
Dependent Manner ◽  
Mineral Density ◽  
Intact Male ◽  
Selective Androgen Receptor Modulator ◽  
Receptor Modulator

The pharmacologic effects of (S)-N-(4-cyano-3-trifluoromethyl-phenyl)-3-(3-fluoro, 4-chlorophenoxy)-2-hydroxy-2-methyl-propanamide (S-23) were characterized in male rats as an animal model of hormonal male contraception. S-23 showed high binding affinity (inhibitory constant = 1.7 ± 0.2 nm) and was identified as a full agonist in vitro. In castrated male rats, the ED50 of S-23 in the prostate and levator ani muscle was 0.43 and 0.079 mg/d, respectively. In intact male rats treated for 14 d, S-23 alone suppressed LH levels by greater than 50% at doses greater than 0.1 mg/d, with corresponding decreases in the size of the prostate but increases in the size of levator ani muscle. In intact male rats treated for up to 10 wk with S-23 and estradiol benzoate (EB; necessary to maintain sexual behavior in rats), S-23 showed biphasic effects on androgenic tissues and spermatogenesis by suppressing serum concentrations of LH and FSH. EB alone showed no effect on spermatogenesis. In the EB + S-23 (0.1 mg/d) group, four of six animals showed no sperm in the testis and zero pregnancies (none of six) in mating trials. After termination of treatment, infertility was fully reversible, with a 100% pregnancy rate observed after 100 d of recovery. S-23 increased bone mineral density and lean mass but reduced fat mass in a dose-dependent manner. This is the first study to show that a selective androgen receptor modulator combined with EB is an effective and reversible regimen for hormonal male contraception in rats. The beneficial effects of S-23 on the muscle, tissue selectivity, and favorable pharmacokinetic properties make it a strong candidate for use in oral male contraception. An aryl-propionamide selective androgen receptor modulator (S-23) is an effective and reversible agent for hormonal male contraception in rats.

scholarly journals Comparison of the Pharmacological Effects of a Novel Selective Androgen Receptor Modulator, the 5α-Reductase Inhibitor Finasteride, and the Antiandrogen Hydroxyflutamide in Intact Rats: New Approach for Benign Prostate Hyperplasia

Endocrinology ◽  
2004 ◽  
Vol 145 (12) ◽  
pp. 5420-5428 ◽  
Author(s):  
Wenqing Gao ◽  
Jeffrey D. Kearbey ◽  
Vipin A. Nair ◽  
Kiwon Chung ◽  
A. F. Parlow ◽  
...  
Keyword(s):  
Androgen Receptor ◽  
Partial Agonist ◽  
Levator Ani ◽  
Male Rats ◽  
Levator Ani Muscle ◽  
Intact Male ◽  
Prostate Hyperplasia ◽  
Tissue Selectivity ◽  
Benign Prostate ◽  
Intact Rats

Abstract Tissue-selective androgen receptor modulators (SARMs) demonstrate tissue selectivity in both castrated and intact male rats, behaving as partial agonists in androgenic tissues (i.e. prostate and seminal vesicle), but full agonists in anabolic tissues (i.e. levator ani muscle). The partial agonist activity of SARMs (compounds S-1 and S-4) in the prostate of intact rats suggested that SARM could be used for androgen suppression in the treatment of benign prostate hyperplasia (BPH). This study was designed to explore the mechanisms of action of SARM and to characterize the tissue selectivity of S-1 in intact male rats compared with that of hydroxyflutamide (antiandrogen) and finasteride (5α-reductase inhibitor), two major drugs used for androgen suppression treatment of BPH. In intact male rats, S-1 (5, 10, and 25 mg/kg) selectively decreased the prostate weight with similar efficacy to finasteride (5 mg/kg), without affecting the levator ani muscle or increasing the plasma levels of testosterone, LH, and FSH. Hydroxyflutamide (0.5, 1, 5, 10, and 25 mg/kg), however, decreased both the prostate and levator ani muscle weights without any selectivity and increased plasma hormone levels in a dose-dependent manner. Furthermore, S-1 and S-4 showed very weak inhibitory effects toward transiently expressed type I and II human 5α-reductase (Ki, &gt;20 μm) during in vitro assays. Therefore, although S-1 and finasteride showed very similar suppressive effects in the prostate of intact male rats, they decreased prostate size via different mechanisms of action. S-1 simply worked as androgen receptor partial agonist, whereas finasteride inhibited prostatic 5α-reductase. These studies indicate that SARMs may demonstrate clinical utility as single agent or combination therapy for BPH.

Cachectic effect of ciliary neurotrophic factor on innervated skeletal muscle

1996 ◽  
Vol 271 (5) ◽  
pp. R1422-R1428 ◽  
Author(s):  
D. Martin ◽  
E. Merkel ◽  
K. K. Tucker ◽  
J. L. McManaman ◽  
D. Albert ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Body Weight ◽  
Muscle Mass ◽  
Neurotrophic Factor ◽  
Skeletal Muscle Mass ◽  
Muscle Wasting ◽  
Body Weight Gain ◽  
Ciliary Neurotrophic Factor ◽  
Female Rats ◽  
Male Rats

Recombinant human ciliary neurotrophic factor (rh-CNTF) was reported to attenuate skeletal muscle wasting in rats after unilateral transection of the sciatic nerve (M. E. Helgren, S. P. Squinto, H. L. Davis, D. J. Parry, T. G. Bolton, C. S. Heck, Y. Zhu, G. D. Yancopoulos, R. M. Lindsay, and P. S. DiStefano. Cell 76: 493-504, 1994). Under the experimental conditions reported herein, the absolute masses of the denervated gastrocnemius and soleus muscles were not increased in mature or immature rats of either sex by treatment with rhCNTF. At the highest doses of rhCNTF (1 and 0.1 mg/kg), increases in the ratio of the masses of the denervated to the contralateral innervated gastrocnemius and soleus muscles could be attributed entirely to a muscle-wasting effect on the contralateral innervated muscle rather than any muscle-sparing effect on the denervated muscle. The muscle-wasting effects of rhCNTF were associated with reductions in body weight gain and reduced food intake. Pair-fed rats lost less body weight and skeletal muscle mass than rhCNTF-injected freely fed rats but experienced significantly greater loss of visceral mass. Male rats displayed greater loss of body weight and skeletal muscle mass than female rats. Recombinant inhibitors of the cachectic cytokines, tumor necrosis factor and interleukin-1, did not significantly alter the wasting effects of rhCNTF. These findings demonstrate that, in contrast to its well-characterized trophic effects on cells of the nervous system, rhCNTF causes atrophy of skeletal muscle by mechanisms involving both anorexia and cachexia based on the results of pair-feeding experiments.

scholarly journals Resveratrol attenuates high-fat diet-induced obesity and the aging-related sarcopenia mitochondrial dysfunction in skeletal muscle

2019 ◽  
Author(s):  
Chyi-Huey Bai ◽  
Javad Alizargar ◽  
Jia-Ping Wu
Keyword(s):  
Skeletal Muscle ◽  
Exercise Training ◽  
Muscle Mass ◽  
Mitochondrial Function ◽  
High Fat Diet ◽  
Skeletal Muscles ◽  
Skeletal Muscle Mass ◽  
Sarcopenic Obesity ◽  
High Fat ◽  
Samp8 Mice

AbstractSarcopenic obesity is a progressive loss of skeletal muscle mass and strength with increases in adiposity. The aim of this study was to investigate the effects of resveratrol on obesity or sarcopenia to potential therapy risk for skeletal muscle declines in physical function. C57BL/6J male mice were fed either a high-fat diet for 4 weeks and resveratrol (low-, middle-, and high-dose) for 8 weeks to express the obesity effect. Samp8 mice sarcopenia skeletal muscle functional deterioration expressed an age-associated decline. Resveratrol (150 mg/Kg BW, daily) was administered by oral gavage two times a week one month of the experimental period. Exercise training based on adaptations in the muscle is training twice a week for 4 weeks. The skeletal muscles from mice in each group were analyzed by H&E staining, TUNEL and western blot analysis to determine mitochondrial function expression, apoptosis and relative fibrosis signaling. Results of the present study indicate that resveratrol in obesity skeletal muscle is linked to an increase in the expression of mitochondrial function involved in Bcl-2 and PI3K/AKT. On the other hand, resveratrol attenuates sarcopenia Samp8 mice, the age-related loss of skeletal muscle mass and mitochondrial function involved in Bad, caspase 3 and IL-6/ERK1. However, exercise training not find a significant difference in sarcopenia skeletal muscles SAMP8 mice. Exercise training didn’t induce sarcopenia skeletal muscle hypertrophy in sarcopenic SAMP8 mice. Therefore, we suggest that resveratrol as a therapeutic potential in the combination of sarcopenia and obesity, the state called sarcopenic obesity.

Anabolic responsiveness of skeletal muscles correlates with androgen receptor protein but not mRNA

2006 ◽  
Vol 84 (2) ◽  
pp. 273-277 ◽  
Author(s):  
Douglas A. Monks ◽  
Will Kopachik ◽  
S. Marc Breedlove ◽  
Cynthia L. Jordan
Keyword(s):  
Skeletal Muscle ◽  
Androgen Receptor ◽  
Skeletal Muscles ◽  
Extensor Digitorum Longus ◽  
Levator Ani ◽  
Extensor Digitorum ◽  
Receptor Protein ◽  
Mrna Levels ◽  
Receptor Mrna ◽  
Androgen Receptor Protein

Anabolic effects of androgens on skeletal muscle are well documented, but the physiological and biochemical bases of these effects are poorly understood. Skeletal muscles that differ in their androgen responsiveness can be used to examine these mechanisms. We compared androgen receptor mRNA and protein levels of the rat levator ani, a perineal skeletal muscle that depends on androgens for its normal maintenance and function with that of the rat extensor digitorum longus, a limb muscle that does not require androgens. Western immunoblotting indicated that androgen receptor protein is significantly elevated in the levator ani relative to the extensor digitorum longus. Surprisingly, steady state androgen receptor mRNA levels were equivalent in these muscles, as determined by Northern blot analysis and quantitative RT-PCR. These results suggest that androgen responsiveness of skeletal muscles is determined by the level of androgen receptor protein in a particular muscle and that androgen receptor protein content is regulated by translational or post-translational mechanisms.

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