title: Early responses of periodontal ligament cells to mechanical stimulus in vivo.
abstract: Previous studies have indicated that human periodontal ligament cells undergo osteoblastic differentiation via the ERK pathway under mechanical stress in vitro. This study aimed to verify this principle in vivo. The right upper first molars of 25 anesthetized rats were loaded with constant forces of 0.1 N for up to 8 hrs. The untreated contralateral side served as a control. Paraffin-embedded sections were analyzed by immunohistochemistry for proliferating cell nuclear antigen (PCNA), runt-related transcription factor 2 (Runx2/Cbfa1), and phosphorylated extracellular signal-regulated kinases 1/2 (pERK1/2). In selected areas under tension, the proportions of Runx2-positive and pERK1/2-positive cells increased within 8 hrs of loading, whereas these proportions in selected areas under pressure were significantly lower than those in control teeth. Moreover, there were no significant changes in the number of PCNA-positive cells. Thus, mechanical stimulus up-regulates Runx2, and this regulation may be achieved via the ERK pathway.
authors.affiliation: Department of Orthodontics, Dental Clinic, University of Bonn, Welschnonnenstr. 17, D-53111 Bonn, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Kawarizadeh
authors.forename: C
authors.initials: C
authors.lastname: Bourauel
authors.forename: W
authors.initials: W
authors.lastname: Götz
authors.forename: A
authors.initials: A
authors.lastname: Jäger
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000502:physiology*; D050659:Core Binding Factor Alpha 1 Subunit / Q000378:metabolism*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D007150:Immunohistochemistry; D008297:Male; D008437:Maxilla; D010069:Oxadiazoles; D010513:Periodontal Ligament / Q000166:cytology / Q000378:metabolism*; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000502:physiology; D013314:Stress, Mechanical; D014086:Tooth Mobility / Q000378:metabolism*; D014087:Tooth Movement Techniques
chemical_list: D050659:Core Binding Factor Alpha 1 Subunit; D010069:Oxadiazoles; D018809:Proliferating Cell Nuclear Antigen; C493717:Runx2 protein, rat; C050143:MO 113; D048049:Extracellular Signal-Regulated MAP Kinases