title: Effect of Estrogen and Food Hardness on Metabolism and Turnover of Condylar Cartilage.
abstract: OBJECTIVE
  To clarify the effect of estrogen and food hardness on condylar cartilage and the cartilage-bone interface.
  
  
  METHODS
  A total of 56 rats were divided into four groups: (1) ovariectomized rats fed a normal (pressed pellet) food, (2) ovariectomized rats fed a soft (powder) food, (3) control rats fed a normal (pressed pellet) food, and (4) control rats fed a soft (powder) food. Some rats (n = 29) were sacrificed at the age of 67 days and others (n = 27) at the age of 87 days, and then 5-μm-thick sagittal paraffin sections were prepared from each temporomandibular joint (TMJ). Toluidine blue staining, in situ hybridization with type X collagen, terminal deoxynucleotidyl transferase and deoxyuridine triphosphate nick end labeling (TUNEL-assay), and tartrate-resistant acid phosphatase (TRAP) histochemistry were performed. Immunohistochemical analyses included cathepsin K, adiponectin, proliferating cell nuclear antigen (PCNA), and type X collagen staining. Analysis of variance and appropriate post-hoc tests were used in all analyses.
  
  
  RESULTS
  Ovariectomy and normal food consistency increased the thickness of condylar cartilage (P < .001), PCNA expression (P < .001) and type X collagen expression (P < .001). Ovariectomy decreased the number (P < .05) and size of osteoclasts (P < .01). Soft food increased the number of cartilage cells stained positively against adiponectin (P < .01).
  
  
  CONCLUSIONS
  Decreased estrogen level and normal food hardness increase the thickness of condylar cartilage by various mechanisms.
authors.forename: Marko
authors.initials: M
authors.lastname: Orajärvi
authors.forename: Irma
authors.initials: I
authors.lastname: Thesleff
authors.forename: Henna
authors.initials: H
authors.lastname: Hartikainen
authors.forename: Aune
authors.initials: A
authors.lastname: Raustia
authors.forename: Pertti
authors.initials: P
authors.lastname: Pirttiniemi
mesh_terms: D000818:Animals; D002356:Cartilage / Q000378:metabolism*; D004967:Estrogens / Q000502:physiology*; D005260:Female; D005502:Food; D006244:Hardness; D008335:Mandibular Condyle / Q000378:metabolism; D051381:Rats
chemical_list: D004967:Estrogens