title: Up-regulation of PKMζ expression in the anterior cingulate cortex following experimental tooth movement in rats.
abstract: OBJECTIVE
  To explore the involvement of synaptic plasticity in pain induced by experimental tooth movement, we evaluated the expression of protein kinase M zeta (PKMζ), an enzyme necessary for maintaining long-term potentiation (LTP) in the anterior cingulate cortex (ACC).
  
  
  METHODS
  Male Sprague-Dawley rats weighing 250-300g were used. The change of the expression of PKMζ in the ACC was measured by western blot, and the mRNA of PKMζ was detected by quantitative real-time PCR 1, 3, 7 days after experimental tooth movement. The average time spent on mouth-wiping behaviour of rats involved in pain perception was detected. After that a selective PKMζ inhibitor, called myristoylated ζ-pseudosubstrate inhibitory peptide (ZIP) was injected into ACC, and the effects of ZIP were evaluated.
  
  
  RESULTS
  The mouth-wiping behaviour of rats was significantly increased 1, 3, and 7 days after experimental tooth movement. Changes in PKMζ levels were not detected on day 1 but were found to be increased 3 days following the tooth movement, and then declined to the baseline 7 days after tooth movement in the ACC. PKMζ mRNA levels were not significantly different between the experimental and sham-treated groups at the three time points. Time spent on mouth-wiping behaviour was reduced after ZIP was injected into ACC 3 days after tooth movement, and the analgesic effect last for at least 24h.
  
  
  CONCLUSIONS
  PKMζ in the ACC acts to maintain the pain induced by experimental tooth movement. Increased expression of PKMζ protein is attributed to persistent translation of PKMζ mRNA. Synaptic plasticity may be involved in the development of tooth movement pain.
authors.affiliation: Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou, China; Department of Orthodontics, Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-sen University, Guangzhou, China.
authors.forename: Yinzi
authors.initials: Y
authors.lastname: Xin
authors.affiliation: Department of Orthodontics, Changsha Stomatological Hospital, Changsha, China.
authors.forename: Xingyu
authors.initials: X
authors.lastname: Liu
authors.affiliation: Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou, China; Department of Orthodontics, Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-sen University, Guangzhou, China. Electronic address: caoyang34@163.com.
authors.forename: Yang
authors.initials: Y
authors.lastname: Cao
authors.affiliation: Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou, China; Department of Orthodontics, Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-sen University, Guangzhou, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Department of Orthodontics, Guangdong Provincial Stomatological Hospital, Affiliated Stomatological Hospital of Southern Medical University, Guangzhou, China.
authors.forename: Chufeng
authors.initials: C
authors.lastname: Liu
mesh_terms: D000818:Animals; D015153:Blotting, Western; D057846:Cell-Penetrating Peptides; D006179:Gyrus Cinguli / Q000201:enzymology*; D055666:Lipopeptides / Q000494:pharmacology; D017774:Long-Term Potentiation; D008297:Male; D009473:Neuronal Plasticity; D010147:Pain Measurement; D011493:Protein Kinase C / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D060888:Real-Time Polymerase Chain Reaction; D014087:Tooth Movement Techniques; D015854:Up-Regulation
chemical_list: D057846:Cell-Penetrating Peptides; D055666:Lipopeptides; D012333:RNA, Messenger; C568285:zeta-inhibitory peptide; D011493:Protein Kinase C; C504730:protein kinase M zeta, rat
keywords: Anterior cingulate cortex; Experimental tooth movement; PKMζ; Pain; ZIP