Up-regulation of p38 Mitogen-activated Protein Kinase during Pulp Injury-induced Glial Cell/Neuronal Interaction in the Rat Thalamus

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• 作者：Tomoatsu Kaneko ; DDS ; PhD^&lowast ; ; ^{tomoendo@dent.niigata-u.ac.jp" class="auth_mail" title="E-mail the corresponding author} ; Uraiwan Chokechanachaisakul ; DDS ; PhD^&dagger ; ; Jun Kawamura ; DDS ; PhD^&dagger ; ; Yusuke Yamanaka ; DDS^&lowast ; ; Takafumi Ito ; DDS^&lowast ; ; Mitsuhiro Sunakawa ; DDS ; PhD^&dagger ; ; ^&Dagger ; ; Hideaki Suda ; DDS ; PhD^&dagger ; ; Takashi Okiji ; DDS ; PhD^&lowast ;
• 关键词：Astrocyte ; central nervous system ; dental pulp ; nerve ; p38-MAPK
• 刊名：Journal of Endodontics
• 出版年：2013
• 出版时间：April 2013
• 年：2013
• 卷：39
• 期：4
• 页码：488-492
• 全文大小：702 K

文摘

We have recently reported that the signal of pulp injury induces both neuronal and glial cell activation in the contralateral thalamus in rats, although the mechanisms of the glial cell/neuronal interaction remain unclear. This study was undertaken to test our hypothesis that p38 mitogen-activated protein kinase (MAPK) signaling pathways are involved in the pulp injury–induced glial cell/neuronal interaction in the thalamus.

Methods

A local anesthetic (lidocaine with epinephrine) or saline (control) was injected into the tissue surrounding the left mandibular first molar of Wistar rats. The tooth was then pulp-exposed, and the cavity was sealed with flowable composite. After 0 (normal pulp with local anesthetic or saline pretreatment), 24, and 72 hours, the contralateral side of thalamus was retrieved and subjected to immunohistochemistry for phospho-p38 MAPK and glial fibrillary acidic protein and real-time polymerase chain reaction analysis of p38-MAPK family (MAPK 13 and MAPK 14) mRNAs.

Results

The area immunopositive to phospho-p38 MAPK increased until 72 hours after pulp exposure in both local anesthetic–pretreated and saline-pretreated animals, but the rate of increase was lower in the local anesthetic–pretreated animals. The density of glial fibrillary acidic protein–expressing astrocytes showed a significant increase only in the saline-pretreated animals. Expression levels of MAPK 13 and MAPK 14 mRNAs increased at 24 hours and still higher at 72 hours in the saline-pretreated animals. Notably, MAPK 13 and MAPK 14 mRNA levels at 24 and 72 hours in the local anesthetic–pretreated animals showed significantly lower levels than those in the saline-pretreated animals.

Conclusions

It was concluded that pulp injury–induced up-regulation of MAPK 13, MAPK 14, and phospho-p38 MAPK in the thalamus was suppressed by the local anesthetic pretreatment, suggesting the involvement of p38 MAPK signaling pathways in the glial cell–neuronal interaction induced by pulpal nociception.