title: Receptor activator of nuclear factor-kappa ligand, OPG, and IGF-I expression during orthodontically induced inflammatory root resorption in the recombinant human growth hormone-treated rats.
abstract: OBJECTIVE
  To investigate the effects of growth hormone (GH) on local receptor activator of nuclear factor-kappa ligand (RANKL), OPG, and IGF-I expression during orthodontically induced inflammatory root resorption in rats.
  
  
  METHODS
  Forty Wistar rats (gender: male; age: 7 weeks) were randomly divided into control and experimental groups. A force of 50 g was applied to move the right upper first molars mesially. The experimental and control groups received daily subcutaneous injections of recombinant human growth hormone (GH; 2 mg/kg) and equivalent volumes of saline, respectively. The rats were sacrificed on days 1, 3, 7, and 14. Micro-computed tomography-reconstructed images of the upper right first molars were used to survey root resorption and tooth movement. Horizontal sections of the maxillae were prepared for hematoxylin and eosin, tartrate-resistant acid phosphatase, and immunohistochemical staining.
  
  
  RESULTS
  Resorption lacunae appeared on the compressed side of the distal buccal root of the right first molar on days 7 and 14. Compared with the control groups, GH-treated groups showed more RANKL-positive cells and osteoclasts on day 3 and more OPG- and IGF-I-positive cells and fewer odontoclasts on days 7 and 14. Indexes of root resorption were lower and tooth movement was faster in the GH-treated groups than in the control groups on days 7 and 14.
  
  
  CONCLUSIONS
  The inhibitory effect of GH on root resorption by heavy force might be mediated by RANKL/OPG and IGF-I. Short-term GH administration may be a method with which to reduce root resorption and shorten treatment time, especially in patients who are susceptible to root resorption.
authors.affiliation: a  Student, The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, China; and Department of Orthodontics, School and Hospital of Stomatology, Wuhan University, Wuhan, China.
authors.forename: Yajun
authors.initials: Y
authors.lastname: Hu
authors.affiliation: b  Lecturer, Department of Dermatology, Taihe Hospital, Hubei University of Medicine, Shiyan, China.
authors.forename: Wentao
authors.initials: W
authors.lastname: Liu
authors.affiliation: c  Associate Professor, Department of Orthodontics, School and Hospital of Stomatology, Wuhan University, Wuhan, China.
authors.forename: Zhijian
authors.initials: Z
authors.lastname: Liu
authors.affiliation: d  Student, Department of Orthodontics, School and Hospital of Stomatology, Wuhan University, Wuhan, China.
authors.forename: Wenying
authors.initials: W
authors.lastname: Kuang
authors.affiliation: e  Professor and Chair, Department of Orthodontics, School and Hospital of Stomatology, Wuhan University, Wuhan, China; and Professor, The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, China.
authors.forename: Hong
authors.initials: H
authors.lastname: He
mesh_terms: D000818:Animals; D002452:Cell Count; D004195:Disease Models, Animal; D019382:Human Growth Hormone / Q000494:pharmacology*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D007334:Insulin-Like Growth Factor I / Q000032:analysis* / Q000187:drug effects; D008297:Male; D008963:Molar / Q000737:chemistry; D010010:Osteoclasts / Q000473:pathology; D053244:Osteoprotegerin / Q000032:analysis* / Q000187:drug effects; D010513:Periodontal Ligament / Q000737:chemistry / Q000187:drug effects; D053245:RANK Ligand / Q000032:analysis* / Q000187:drug effects; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D011994:Recombinant Proteins; D012391:Root Resorption / Q000378:metabolism*; D000071681:Tartrate-Resistant Acid Phosphatase / Q000032:analysis; D013997:Time Factors; D014087:Tooth Movement Techniques / Q000009:adverse effects*; D055114:X-Ray Microtomography / Q000379:methods
chemical_list: D053244:Osteoprotegerin; D053245:RANK Ligand; D011994:Recombinant Proteins; C506032:Tnfrsf11b protein, rat; D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I; D000071681:Tartrate-Resistant Acid Phosphatase
keywords: IGF-I; OPG; RANKL; Root resorption