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Structure:
![]() All anabolic steroids are chemical derivatives of the male sex hormone, testosterone. Due to testosterone's short biological half-life, pharmacological use requires the steroid be modified to slow metabolism by the liver. Typically, oral steroids are modified primarily by alkylation (replacing an H with a CH3 group), while injectable steroids are modified by esterification of the hydroxyl group. |
Once in the nucleus, the steroid appears to enhance transcription of specific genes. The resulting mRNA is processed and sent out of the nucleus, resulting in increased protein synthesis.
Catabolic inhibition may also occur in the nucleus if the complex inhibits the transcription of catabolic enzymes.
The presence of the androgen receptor indicates a tissue is androgen sensitive, and it's concentration gives an indication of how sensitive. The receptor is present in a number of organs, including skeletal muscle. Skeletal muscle typically contains 0.5-3 femto (1E-12) moles per milligram of protein, while other androgen sensitive organs, like the prostate gland, may have up to 25 times more receptors.
A final observation about feedback in biological systems: in a perfect example of biological control, a byproduct of testosterone metabolism is estradiol, which enhances catabolism. Thus, overadministration of testosterone-analog steroids can feed-back and minimize results.
Effects
Testosterone's effects are generally broken into two classes: anabolic
and androgenic. Both appear to result from the same
signalling pathway as there are no proteins with anabolic effects independent
of androgenic effects.
These should provide a good beginning for a more detailed investigation
of anabolic steroid behavior. If you are considering
them as part of a training program, please consult a physician.
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