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.

Chronic Alcohol Intake And Resistance Training On Skeletal Muscle Androgen Receptor Protein Content In Rats

2005 ◽  
Vol 37 (Supplement) ◽  
pp. S238
Author(s):  
Jakob L. Vingren ◽  
Lymperis P. Koziris ◽  
Kim C. Westerlind ◽  
Daniel A. Judelson ◽  
Barry A. Spiering ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Androgen Receptor ◽  
Resistance Training ◽  
Protein Content ◽  
Alcohol Intake ◽  
Receptor Protein ◽  
Chronic Alcohol ◽  
Androgen Receptor Protein

scholarly journals Effects of re-feeding after prolonged starvation on pyruvate dehydrogenase activities in heart, diaphragm and selected skeletal muscles of the rat

1989 ◽  
Vol 262 (2) ◽  
pp. 669-672 ◽  
Author(s):  
M C Sugden ◽  
M J Holness
Keyword(s):  
Skeletal Muscle ◽  
Pyruvate Dehydrogenase ◽  
Tibialis Anterior ◽  
Skeletal Muscles ◽  
Extensor Digitorum Longus ◽  
Glycogen Synthesis ◽  
Extensor Digitorum ◽  
Hepatic Glycogen ◽  
Prolonged Starvation ◽  
Adductor Longus

We investigated the capacity for pyruvate oxidation in skeletal muscle, diaphragm and heart after starvation and re-feeding. Starvation for 48 h decreased pyruvate dehydrogenase (PDH) activity in soleus (by 47%), extensor digitorum longus (64%), gastrocnemius (86%), diaphragm (87%), adductor longus (90%), tibialis anterior (92%) and heart (99%). Chow re-feeding increased PDH activity in all muscles to 43-78% of the fed value within 2 h. However, complete re-activation was not observed for at least 4-6 h, during which time hepatic glycogen was replenished. We discuss the importance of muscle PDH activity in relation to sparing carbohydrate for hepatic glycogen synthesis.

Chronic Alcohol Intake And Resistance Training On Skeletal Muscle Androgen Receptor Protein Content In Rats

2005 ◽  
Vol 37 (Supplement) ◽  
pp. S238
Author(s):  
Jakob L. Vingren ◽  
Lymperis P. Koziris ◽  
Kim C. Westerlind ◽  
Daniel A. Judelson ◽  
Barry A. Spiering ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Androgen Receptor ◽  
Resistance Training ◽  
Protein Content ◽  
Alcohol Intake ◽  
Receptor Protein ◽  
Chronic Alcohol ◽  
Androgen Receptor Protein

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.

Androgen increases androgen receptor protein while decreasing receptor mRNA in LNCaP cells

1991 ◽  
Vol 76 (1-3) ◽  
pp. 79-88 ◽  
Author(s):  
Arnon Krongrad ◽  
Carol M. Wilson ◽  
Jean D. Wilson ◽  
Diane R. Allman ◽  
Michael J. McPhaul
Keyword(s):  
Androgen Receptor ◽  
Receptor Protein ◽  
Lncap Cells ◽  
Receptor Mrna ◽  
Androgen Receptor Protein

Capillarity and blood flow of transplanted skeletal muscles of cats

1981 ◽  
Vol 241 (4) ◽  
pp. H630-H636 ◽  
Author(s):  
T. P. White ◽  
L. C. Maxwell ◽  
D. M. Sosin ◽  
J. A. Faulkner
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Skeletal Muscles ◽  
Extensor Digitorum Longus ◽  
Muscle Fibers ◽  
Extensor Digitorum ◽  
Maximal Flow ◽  
Total N ◽  
Total Ischemia ◽  
Peripheral Areas

After transplantation, skeletal muscle fibers and the microvasculature degenerate and then regenerate. The structural and functional characteristics of autografted muscle change with time and ultimately stabilize. Capillarity, blood flow, or fatigability was measured in control (total n = 22) and in autografted (total n = 42) extensor digitorum longus muscles of cats. From 10 to 180 days after transplantation, the capillaries per square millimeter in peripheral areas of autografts averaged 65% of control, and from 180 to 518 days, 45% of control. Resting blood flow in autografts increased eventually from total ischemia at the time of transplantation to values 400% of control. After 400 days, resting blood flow returned to control values. The blood flow of autografts increased in response to twitch stimulation, reaching maximal value (24.4 +/- 1.4 ml . 100 g-1 . min-1) at 1 twitch . s-1 . The maximal blood flow of autografts was comparable to the submaximal blood flow at 1 twitch . s-2 of controls and was 30% of the maximal flow of controls obtained at 4 twitches . s-1. The maximal blood flow in autografts did not increase from 80 to 460 days. When stimulated with repetitive twitches, autografts fatigued more rapidly than controls.

Human growth hormone treatment of hypophysectomized rats increases the proportion of type-1 fibres in skeletal muscle

1989 ◽  
Vol 123 (3) ◽  
pp. 429-NP ◽  
Author(s):  
C. M. Ayling ◽  
B. H. Moreland ◽  
J. M. Zanelli ◽  
D. Schulster
Keyword(s):  
Skeletal Muscle ◽  
Fibre Type ◽  
Extensor Digitorum Longus ◽  
Human Growth ◽  
Hormone Treatment ◽  
Pituitary Hormones ◽  
Extensor Digitorum ◽  
Replacement Treatment ◽  
Hypophysectomized Rats

ABSTRACT The studies describe alterations after hypophysectomy in the proportion of the type-1 and type-2 fibres in rat skeletal muscles, and the effects of replacement treatment with pituitary human (h) GH. Cytochemical analysis of myosin ATPase, succinate dehydrogenase and lactate dehydrogenase activities in sections of rat hind limb muscles were used as markers of fibre type and revealed that hypophysectomy reduced the proportion of type-1 fibres by 50% in soleus and in extensor digitorum longus muscles. This reduction in the proportion of type-1 fibres was accompanied by the appearance of transitional fibres (type 2C/1B). Following seven daily injections of hGH (60 mIU/day) to hypophysectomized rats, the proportion of type-1 fibres in both soleus and in extensor digitorum longus was increased with a concomitant reduction in the number of transitional fibres. After 11 days of treatment, all these transitional fibres had reverted back to type-1 fibres. Only hGH was observed to elicit this effect; injections of other pituitary hormones had no effect on the proportions of these transitional fibres. These alterations in fibre type occurred more rapidly than the changes reported after prolonged electrical stimulation of muscle or following extended exercise. These findings suggest that hypophysectomy and GH injection can result in a rapid alteration in the fibre composition of skeletal muscle, which may have important implications in terms of the resistance to fatigue and speed of contraction of the muscle. Journal of Endocrinology (1989) 123, 429–435

scholarly journals Identification in skeletal muscle of a distinct extracellular pool of amino acids, and its role in protein synthesis

1971 ◽  
Vol 121 (5) ◽  
pp. 817-827 ◽  
Author(s):  
R. C. Hider ◽  
E. B. Fern ◽  
D. R. London
Keyword(s):  
Skeletal Muscle ◽  
Amino Acids ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Incubation Medium ◽  
Extensor Digitorum Longus ◽  
Extensor Digitorum ◽  
Longus Muscle ◽  
Kinetics Of

1. The kinetics of radioactive labelling of extra- and intra-cellular amino acid pools and protein of the extensor digitorum longus muscle were studied after incubations with radioactive amino acids in vitro. 2. The results indicated that an extracellular pool could be defined, the contents of which were different from those of the incubation medium. 3. It was concluded that amino acids from the extracellular pool, as defined in this study, were incorporated directly into protein.

Glutamine synthetase induction by glucocorticoids is preserved in skeletal muscle of aged rats

1996 ◽  
Vol 271 (6) ◽  
pp. E1061-E1066 ◽  
Author(s):  
D. Meynial-Denis ◽  
M. Mignon ◽  
A. Miri ◽  
J. Imbert ◽  
E. Aurousseau ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Glutamine Synthetase ◽  
Skeletal Muscles ◽  
Female Rats ◽  
Mrna Levels ◽  
Aged Rats ◽  
Adult Rats ◽  
Adult Age ◽  
Slow Twitch ◽  
Fast Twitch

Glutamine synthetase (GS) is a glucocorticoid-inducible enzyme that has a key role for glutamine synthesis in muscle. We hypothesized that the glucocorticoid induction of GS could be altered in aged rats, because alterations in the responsiveness of some genes to glucocorticoids were reported in aging. We compared the glucocorticoid-induced GS in fast-twitch and slow-twitch skeletal muscles (tibialis anterior and soleus, respectively) and heart from adult (age 6-8 mo) and aged (age 22 mo) female rats. All animals received dexamethasone (Dex) in their drinking water (0.77 +/- 0.10 and 0.80 +/- 0.08 mg/day per adult and aged rat, respectively) for 5 days. Dex caused an increase in both GS activity and GS mRNA in fast-twitch and slow-twitch skeletal muscles from adult and aged rats. In contrast, Dex increased GS activity in heart of adult rats, without any concomitant change in GS mRNA levels. Furthermore, Dex did not affect GS activity in aged heart. Thus the responsiveness of GS to an excess of glucocorticoids is preserved in skeletal muscle but not in heart from aged animals.

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