title: [Changes of protein kinases Mζ expression in the anterior cingulate cortex after applying three different magnitude of orthodontic force].
abstract: OBJECTIVE
  To investigate the regulatory effect of central synaptic plasticity on pain induced by experimental tooth movement and to analyzethe expression of protein kinases Mζ (PKMζ) in the anterior cingulate cortex (ACC) after applying different magnitude of orthodontic force.
  
  
  METHODS
  One hundred and thirty-six male Sprague-Dawley (SD) rats (200-250 g) were used in this study. Orthodontic tooth movement devices were placed on the teeth in the experimental group, and different orthodontic forces (0.39, 0.78, 1.17 N) were applied to move the maxillary first molars, respectively. The same mechanical devices were placed on the teeth in sham-treated group and no orthodontic force was applied. No orthodontic procedure was applied in blank control group. The average time spent on mouth- wiping behavior in each group was recorded after experimental tooth movement. Brain tissue of the anterior cingulate cortex was isolated on day 3 after experiment, and the expression level of PKMζ was analyzed with the method of immunohistochemistry and enzyme-linked immune sorbent assay. ζ-pseudosubstrate inhibitory peptide (ZIP), a selective inhibitor for PKMζ, was injected into ACC on day 3 after experimental tooth movement, and the effects of ZIP on mouth-wiping behavior were evaluated.
  
  
  RESULTS
  No statistical difference was found between the blank control group and the sham- treated group in the average time spent on mouth-wiping, value of A and expression level of PKMζ (P > 0.05). Compared with the sham-treated group and blank control group, the average time of mouth-wiping behavior [(58.6±6.9), (66.3±7.8), (78.9±8.7) s], value of A (4 569±454, 6 850±365, 8 294±558) and expression level of PKMζ [(0.32±0.02), (0.34±0.02), (0.36±0.02) mg/L] in 0.39, 0.78, 1.17 N force group were found to be up-regulated with the increase of orthodontic force (P < 0.05). LSD test in three experimental sub-group showed statistical difference (P < 0.05). After microinjection of ZIP, the average time spent on mouth-wiping behavior significantly decreased (P < 0.01), while microinjecting saline did not change rats' mouth-wiping behavior (P > 0.05).
  
  
  CONCLUSIONS
  More pain caused by increased orthodontic force maybe due to the up-regulation of PKMζ in the anterior cingulate cortex.
authors.affiliation: Department of Orthodontics, Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-sen University & Guangdong Provincial Key Laboratory of Stomatology, Guangzhou 510055, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Chen
authors.forename: Yinzi
authors.initials: Y
authors.lastname: Xin
authors.forename: Chufeng
authors.initials: C
authors.lastname: Liu
authors.forename: Yijia
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Email: caoyang34@163.com.
authors.forename: Yang
authors.initials: Y
authors.lastname: Cao
mesh_terms: D000818:Animals; D001522:Behavior, Animal; D006179:Gyrus Cinguli / Q000201:enzymology*; D008297:Male; D008437:Maxilla; D008963:Molar; D009473:Neuronal Plasticity; D011493:Protein Kinase C / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors; D014087:Tooth Movement Techniques / Q000295:instrumentation*; D015854:Up-Regulation
chemical_list: D011493:Protein Kinase C; C504730:protein kinase M zeta, rat