Does the AR receptor make a difference in eugonadal men?

[powerliftmike]

I hear alot of talk on the forums about AR binding and all the anabolic effects brought about from the AR. Well that appears to be false:

After puberty, the androgen receptor in striated muscle is down-regulated (9); the androgen receptor in skeletal muscle is therefore virtually saturated with the physiological concentrations of testosterone present. Because there is little 5{alpha}-reductase activity in skeletal muscle (10), testosterone and possibly circulating DHT appear to be the key hormones for androgen action. In vitro studies have demonstrated that the dose–response relationship of testosterone on growth of skeletal muscle reaches a plateau once the physiological concentration is exceeded (11). With supraphysiological doses of testosterone, the anabolic effects may therefore be evoked through a separate mechanism independent of the androgen receptor, e.g., an anticatabolic effect based on an antiglucocorticoid action (12).

Some indirect evidence supports an anticatabolic effect of androgens. AAS can displace glucocorticoids bound to the glucocorticoid receptor. Antagonists of glucocorticoid action can prevent the muscle atrophy that follows orchidectomy, and urinary free cortisol increases with administration of large doses of AAS. Clinical evidence can be derived from patients who have the androgen insensitivity syndrome as a result of inactivating mutations in the androgen receptor gene. In a recent case study (13), a patient with androgen insensitivity syndrome resulting from a single amino acid substitution (Arg-608 to Lys) in the DNA-binding domain of the androgen receptor received pharmacological doses of testosterone enanthate (5 mg/kg per day for 10 days). Although there were no treatment effects that suppressed gonadotropin and sex-hormone-binding globulin or sebum excretion, testosterone administration resulted in a positive nitrogen balance of 3 g/24 h, similar to that in healthy adult men. Hence, these data indirectly support the hypothesis that the effect of supraphysiological doses of testosterone on muscle is probably mediated through an antiglucocorticoid action independent of the androgen receptor.

(Clinical Chemistry. 1997;43:1289-1292.)

[BajanBastard]

This 'study' misses one vital point; AR concentrations are significantly increaced by supraphysiological levels of androgens in the body. Can i get the study for ref for # 11?

[powerliftmike]

This 'study' misses one vital point; AR concentrations are significantly increaced by supraphysiological levels of androgens in the body. Can i get the study for ref for # 11?

Sure. 11 is:

Bartsch W, Krieg M, Voigt KD. Regulation and compartmentalization of androgens in the rat prostate and muscle. J Steroid Biochem 1983;19:929-937.

[BajanBastard]

Thanks Mike.