Androgens

Testosterone

    Androgens are anabolic steroids, more appropriately called androgenic anabolic steroids. 

One of their main actions is to stimulate protein synthesis - this leads to increased skeletal muscle mass.  Testosterone is also responsible for fetal sexual differentiation, high levels of testosterone during female fetal development can lead to ambiguous or masculinized genitalia.

 

In males, testosterone acts through two main pathways

  1. Conversion to 5 a-Dihydrotestosterone (DHT)

  2. Aromatization to estradiol

 

In females, testosterone is converted from ovarian and adrenal androgen.

 

 

 

 

 

Figure 5.1 Chemical structure of testosterone

(http://www.biopsychiatry.com/testosterone/testosterone.jpg)

 

Figure 5.2 Biochemical pathways of testosterone metabolism

http://www.antiaging.com/images/Testosterone_biochem.gif)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Actions in Bone

    In general, testosterone stimulates long bone growth and helps maintain peak bone density.  It helps women reach their peak bone mass and is responsible for the sexually dimorphic greater bone mass in men.

 

More specifically, it:

 

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Promotes chondrocyte maturation, stimulates linear endochondral bone growth

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Directly inhibits bone resorption and osteoclastogenesis

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Increases periosteal bone apposition

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Increased bone mass in males

 

Abnormal Levels

 

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Low levels: decreased cortical bone mass, changes to trabecular architecture, osteopenia

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Supraphysiological levels
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During growth: premature puberty and epiphyseal closure (although linear growth is stimulated, increased estradiol causes fusion).

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After growth: increased periosteal apposition of bone

 

 

 

 

 

 

 

 

 

Figure 5.3 Physical changes associated with anabolic steroid use

(http://www.sdi-labs.com/images/image1.jpg)

Paleopathology

    There is no documented paleopathological or archaeological evidence of testosterone abnormalities.  As anabolic androgenic steroid abuse is a fairly recent phenomenon it is likely that the skeletal changes associated with steroid abuse will become more prevalent in a forensic context.

 

Possible observable paleopathological changes

 

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Osteoporosis: a decrease in testosterone level is associated with disorganization of trabecular architecture and with osteopenia.

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Increased periosteal apposition in anabolic steroid users.
 

Introduction Development hGH Estrogen Testosterone Summary ReferencesBack Next

Page References

Benito M, Vasilic B, Wehrli F, Bunker B, Wald M, Gomberg B, Wright A, Zemel B, Cucchiara A, and Snyder P. 2005. Effect of testosterone replacement on trabecular architecture in hypogonadal men. J Bone Miner Res 20:1785-1791.

Compston J. 2001. Sex steroids and bone. Physiol Rev 81:419-447.

Friedl K. 2000a. Effect of anabolic steroid use on body composition and physical performance. In: Yesalis C, editor. Anabolic steroids in sports and exercise. Champaign: Human Kinetics. p 139-174.

Grumbach MM and DM Styne (2003). Puberty: Ontogeny, neuroendocriniology, physiology, and disorders. In: Larsen P, Kronenberg H, Melmed S and Polonsky K, editors. Williams Textbook of Endocrinology, 10th Edition. Philadelpia: Saunders. accessed online at http://home.mdconsult.com.lp.hscl.ufl.edu/das/book/63998403-2/view/1091.

Kung A and Gu J. 2005. Estrogens and androgens on bone metabolism. In: Deng H and Liu Y, editors. Current Topics in Bone Biology. Singapore: World Scientific. p 213-250.