title: Novel insights in the regulation and mechanism of androgen action on bone.
abstract: OBJECTIVE
  This review provides an update on the associations of testosterone, estrogens, sex hormone binding globulin, GH-IGF-I, osteocalcin and mechanical loading with relevance to skeletal health.
  
  
  RESULTS
  The simple concept of a dual model of action of androgens, i.e. either directly via the androgen receptor or indirectly by estrogens, is proving more complicated because of novel interactions of these hormones and their receptors with other hormonal as well as mechanical signals.
  
  
  CONCLUSIONS
  Testosterone - in contrast with estrogen - is not uniformly associated with fracture risk in men. However, androgen receptor mediated action is clearly important for trabecular bone maintenance in male mice whereas both estrogens and androgens regulate cortical bone growth. The osteoblast and osteocyte appear to be involved in such androgen receptor mediated action on bone in male mice. Studies in mice also showed an unexpected interaction between osteocalcin and testosterone production in males and, vice versa, between ovarian production of follicle-stimulating hormone with testosterone and potentially bone formation.
authors: Clinical and Experimental Endocrinology, Department of Experimental Medicine, KU Leuven, Leuven, Belgium.
authors: Mieke
authors: M
authors: Sinnesael
authors: Frank
authors: F
authors: Claessens
authors: Steven
authors: S
authors: Boonen
authors: Dirk
authors: D
authors: Vanderschueren
mesh_terms: D000728:Androgens / Q000378:metabolism* / Q000627:therapeutic use; D000818:Animals; D050071:Bone Density Conservation Agents / Q000378:metabolism / Q000627:therapeutic use; D001846:Bone Development / Q000187:drug effects; D001842:Bone and Bones / Q000187:drug effects / Q000502:physiology*; D004967:Estrogens / Q000172:deficiency / Q000378:metabolism / Q000627:therapeutic use; D005260:Female; D006801:Humans; D008297:Male; D010006:Osteoblasts / Q000187:drug effects / Q000378:metabolism; D015675:Osteocalcin / Q000378:metabolism; D010010:Osteoclasts / Q000187:drug effects / Q000378:metabolism; D010024:Osteoporosis / Q000453:epidemiology / Q000378:metabolism / Q000517:prevention & control; D011944:Receptors, Androgen / Q000737:chemistry / Q000378:metabolism*; D012307:Risk Factors; D012727:Sex Characteristics; D015398:Signal Transduction / Q000187:drug effects; D016474:Weight-Bearing
chemical_list: D000728:Androgens; D050071:Bone Density Conservation Agents; D004967:Estrogens; D011944:Receptors, Androgen; D015675:Osteocalcin