J Orofac Pain 29 (2015), No. 3 20. Aug. 2015
J Orofac Pain 29 (2015), No. 3 (20.08.2015)
Effect of Estrogen and Food Hardness on Metabolism and Turnover of Condylar Cartilage
Orajärvi, Marko / Thesleff, Irma / Hartikainen, Henna / Raustia, Aune / Pirttiniemi, Pertti
Aims: 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).
Conclusion: Decreased estrogen level and normal food hardness increase the thickness of condylar cartilage by various mechanisms.
Keywords: adiponectin, estrogen, food hardness, loading, mandibular condylar cartilage, osteoclast, PCNA, proliferation, TRAP, type X collagen