The IGF-I/IGFBP-3 system in gingival crevicular fluid and dependence on application of fixed force.
BACKGROUND
During application of orthodontic force on the tooth, various molecular parameters associated with tissue remodeling are changed. IGF-I is a regulatory protein produced during periodontal regeneration. IGF binding proteins-3 (IGFBP-3), a specific IGF-I binding protein, is the major regulatory factor of IGF-I activity.


OBJECTIVE
We tested the hypothesis that changes in the IGF-I/ IGFBP-3 system occur during fixed force application to the tooth and that these changes are detectable in the gingival crevicular fluid (GCF).


METHODS
IGFBP-3 and IGF-I secretion into gingival crevicular fluid (GCF) was analyzed by Western blotting and immunoradiometric assay (IRMA), respectively, in GCF of 6 healthy subjects just prior to and during orthodontics treatment using fixed appliances.


RESULTS
We observed a significant time-dependent decrease of IGFBP-3 content in GCF during orthodontic treatment (4 h and 10 days). Reduction in levels of intact, glycosylated 47 kDa form of IGFBP-3 was associated with its degradation and the appearance of intermediate breakdown products. IGF-I levels were significantly increased 4 h after application of orthodontic force, while they were significantly reduced 10 days after the start of treatment.


CONCLUSIONS
IGFBP-3 secretion into GCF and its molecular structure are modified by the fixed force of orthodontic treatment. Alterations in IGFBP-3 appear to be unrelated to the binding to IGF-I, suggesting an IGF-independent role of this binding protein in tooth movement.
Laboratory of Biochemistry and Molecular Biology, San Paolo University Hospital, School of Medicine, Milan, Italy.
M
M
Toia
R
R
Galazzo
C
C
Maioli
R
R
Granata
F
F
Scarlatti
D000293:Adolescent; D000328:Adult; D015153:Blotting, Western; D016723:Bone Remodeling / Q000502:physiology*; D002648:Child; D005260:Female; D005883:Gingival Crevicular Fluid / Q000378:metabolism*; D006031:Glycosylation; D006801:Humans; D015592:Immunoradiometric Assay; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000378:metabolism*; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D008297:Male; D013997:Time Factors; D014087:Tooth Movement Techniques
D018972:Insulin-Like Growth Factor Binding Protein 3; D007334:Insulin-Like Growth Factor I