Dietary loading and aggrecanase-1/TIMP-3 expression in rat mandibular condylar cartilage.
OBJECTIVE
To examine the expression of aggrecanase-1 and a tissue inhibitor of metalloproteinases (TIMP-3) in the condylar cartilage of young rats and to determine their relationship during altered dietary loading at different time points after weaning.


METHODS
One hundred Sprague-Dawley rats were randomly assigned to 1 of 2 groups: the soft-diet group, which served as the control group (n=50), or the hard-diet group, which served as the experimental group (n=50). Ten soft- and 10 hard-diet rats were killed at 6 hours, 12 hours, 24 hours, 48 hours, and 9 days after weaning (i.e., after initiation of diet change for hard-diet rats). The right-side temporomandibular joints (TMJs) were prepared for immunohistochemical staining. The cartilage from the left-side mandibular condyles of all 10 animals in each group was combined for Western blot analysis.


RESULTS
Immunohistochemical analysis revealed strong staining for aggrecanase-1 localized mainly in the chondrocytes of proliferative and upper hypertrophic cartilage zones at all time points in both groups. The immunohistological expression of aggrecanase-1 was significantly higher in the hard-diet group at 12 and 24 hours than in the soft-diet group. Strong staining for TIMP-3 was mainly localized in the chondrocytes of proliferative and upper hypertrophic zones at all time points in both groups. The expression of TIMP-3 in the hard-diet group was at a significantly lower level compared to the soft-diet group at 6 hours. Western blot analysis also showed time-related differences in aggrecanase-1 and TIMP-3, but there was no significant difference between the 2 groups.


CONCLUSIONS
The temporary change in aggrecanase-1 and TIMP-3 expression reflects the complex interaction of these enzymes in the physiologic range and cartilage response to altered dietary loading.
Yu
Dahai
D
Department of Prosthetic Dentistry and Stomatognathic Physiology, Faculty of Medicine Institute of Dentistry University of Oulu, Finland.
Tiilikainen
Petri
P
Raustia
Aune
A
Pirttiniemi
Pertti
P
D051722:ADAM Proteins / Q000032:analysis*; D000071121:ADAMTS4 Protein; D000818:Animals; D002358:Cartilage, Articular / Q000201:enzymology*; D004032:Diet; D005260:Female; D008335:Mandibular Condyle / Q000201:enzymology*; D011348:Procollagen N-Endopeptidase / Q000032:analysis*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013704:Temporomandibular Joint / Q000201:enzymology*; D019717:Tissue Inhibitor of Metalloproteinase-3 / Q000032:analysis*
D019717:Tissue Inhibitor of Metalloproteinase-3; D051722:ADAM Proteins; D011348:Procollagen N-Endopeptidase; D000071121:ADAMTS4 Protein