title: Insulin-like growth factor-I stimulates acromegaly-like specific mandibular enlargement in rats.
abstract: To help us investigate the time course of mandibular enlargement in acromegaly or acrogiantism to determine the most suitable period for occlusal treatment in this disease, our aim was to develop a rat model of acromegaly (acrogiantism). In this study, prominent mandibular enlargement was induced by continuous subcutaneous infusion of human recombinant insulin-like growth factor-I (IGF-I) (640 microg/day) in 10-week-old male rats for 4 weeks (n = 6); the control sham-operated group was injected with saline alone (n = 6). Circulating human IGF-I was clearly detectable in the IGF-I group during the four-week administration period, while endogenous rat IGF-I levels decreased. Total IGF-I (human + rat) increased significantly during administration, returning to control levels afterwards. The length of every bone examined (mandible, maxilla, and femur) showed a significant increase compared to control rats, especially the mandible. Although the mandible did not continue to grow after discontinuation of IGF-I administration, it did not return to control size, unlike the maxilla and femur, and disharmonious jaw size (between maxilla and mandible) persisted even after circulating IGF-I levels normalized. These findings in our rat model suggest that mandibular occlusal treatment should only be considered for acromegalic (acrogiantic) patients after serum IGF-I levels have normalized and bone growth has ceased.
authors.affiliation: Department of Oral Diagnosis, Tohoku University Graduate School of Dentistry, Sendai 980-8575, Japan. machapy@mail.tains.tohoku.ac.jp
authors.forename: M
authors.initials: M
authors.lastname: Iikubo
authors.forename: H
authors.initials: H
authors.lastname: Ikeda
authors.forename: A
authors.initials: A
authors.lastname: Kobayashi
authors.forename: I
authors.initials: I
authors.lastname: Kojima
authors.forename: K
authors.initials: K
authors.lastname: Hashimoto
authors.forename: M
authors.initials: M
authors.lastname: Sakamoto
authors.forename: T
authors.initials: T
authors.lastname: Sasano
mesh_terms: D000172:Acromegaly / Q000139:chemically induced*; D000818:Animals; D001835:Body Weight / Q000187:drug effects; D001846:Bone Development / Q000187:drug effects*; D004195:Disease Models, Animal; D007334:Insulin-Like Growth Factor I / Q000378:metabolism / Q000494:pharmacology*; D008297:Male; D008334:Mandible / Q000187:drug effects* / Q000254:growth & development; D008437:Maxilla / Q000187:drug effects / Q000254:growth & development; D051381:Rats; D017208:Rats, Wistar
chemical_list: D007334:Insulin-Like Growth Factor I