title: PTHrP regulates chondrocyte maturation in condylar cartilage.
abstract: PTHrP is a key factor regulating the pace of endochondral ossification during skeletal development. Mandibular advancement solicits a cascade of molecular responses in condylar cartilage. However, the pace of cellular maturation and its effects on condylar growth are still unknown. The purpose of this study was to evaluate the pattern of expression of PTHrP and correlate it to cellular dynamics of chondrocytes in condylar cartilage during natural growth and mandibular advancement. We fitted 35-day-old Sprague-Dawley rats with functional appliances. Experimental animals with matched controls were labeled with bromodeoxyuridine 3 days before their death, so that mesenchymal cell differentiation could be traced. Mandibular advancement increased the number of differentiated chondroblasts and subsequently increased the cartilage volume. Higher levels of PTHrP expression in experimental animals coincided with the slowing of chondrocyte hypertrophy. Thus, mandibular advancement promoted mesenchymal cell differentiation and triggered PTHrP expression, which retarded their further maturation to allow for more growth.
authors.affiliation: Hard Tissue Biology and Repair Research Group and Orthodontics, Faculty of Dentistry, The University of Hong Kong, Prince Philip Dental Hospital, 34 Hospital Road, Hong Kong SAR, China. rabie@hkusua.hku.hk
authors.forename: A B M
authors.initials: AB
authors.lastname: Rabie
authors.forename: G H
authors.initials: GH
authors.lastname: Tang
authors.forename: H
authors.initials: H
authors.lastname: Xiong
authors.forename: U
authors.initials: U
authors.lastname: Hägg
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D002454:Cell Differentiation / Q000502:physiology; D002455:Cell Division / Q000502:physiology; D019902:Chondrocytes / Q000378:metabolism / Q000502:physiology*; D004396:Coloring Agents; D005260:Female; D006132:Growth Plate / Q000254:growth & development* / Q000502:physiology; D007091:Image Processing, Computer-Assisted; D019186:Mandibular Advancement; D008335:Mandibular Condyle / Q000254:growth & development* / Q000502:physiology; D008648:Mesoderm / Q000502:physiology; D017289:Orthodontic Appliances, Functional; D010281:Parathyroid Hormone / Q000032:analysis* / Q000502:physiology; D044162:Parathyroid Hormone-Related Protein; D036361:Peptide Hormones / Q000032:analysis* / Q000502:physiology; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D004396:Coloring Agents; D010281:Parathyroid Hormone; D044162:Parathyroid Hormone-Related Protein; D036361:Peptide Hormones