title: [Physiopathology of osteoporosis].
abstract: OBJECTIVE
  The pathophysiology of osteoporosis has seen many recent progress especially with the use of genetically modified animal models.
  
  
  BACKGROUND
  Among many discoveries, one can notice the crucial role of LRP5, GH, IGF-1 and the sex hormones receptors in the acquisition of the peak bone mass, the control of bone remodeling by the sympathetic nervous system and his implication as a transmitter of mechanical loading in bone. Also, the role of estrogen and androgen receptors as well as the aromatase is specified according to sexes. The role of growth plate's chondrocytes in the installation of the trabecular bone network is better and better demonstrated. The greater periosteal apposition in men, mediated by androgens receptor, seems to explain the greatest radial growth and so the greatest bone resistance to mechanical strains like a lower fracture rate in men compared to women. The bone microarchitecture and quality explain an important part of the mechanical properties of bones and why considering the same bone mass one bone is breaking and another one not.
  
  
  CONCLUSIONS
  Many therapeutic applications should finalize the discovery of these new bone cells signalisation pathways.
authors.affiliation: Service de rhumatologie, CHU de Caen, avenue de la Côte-de-Nacre, 14033 Caen, France.
authors.forename: Régis
authors.initials: R
authors.lastname: Levasseur
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Sabatier
authors.forename: Christian
authors.initials: C
authors.lastname: Marcelli
mesh_terms: D000818:Animals; D016723:Bone Remodeling / Q000235:genetics* / Q000502:physiology*; D004195:Disease Models, Animal; D013006:Growth Hormone / Q000235:genetics / Q000494:pharmacology; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000235:genetics / Q000494:pharmacology; D026502:LDL-Receptor Related Proteins; D060492:Low Density Lipoprotein Receptor-Related Protein-5; D010024:Osteoporosis / Q000235:genetics* / Q000503:physiopathology*; D011944:Receptors, Androgen; D011960:Receptors, Estrogen; D011973:Receptors, LDL / Q000235:genetics; D012307:Risk Factors; D015398:Signal Transduction
chemical_list: D026502:LDL-Receptor Related Proteins; C555482:LRP5 protein, human; D060492:Low Density Lipoprotein Receptor-Related Protein-5; D011944:Receptors, Androgen; D011960:Receptors, Estrogen; D011973:Receptors, LDL; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone