Contribution of capsaicin-sensitive innervation to the continuous eruption of the rat mandibular incisors
- 53 Downloads
A major component of tooth innervation is made of capsaicin-sensitive primary afferents (CSPA). These fibers play a key role in tooth pain and inflammation; little is known, however, about the role of CSPA in tooth eruption. The aim of this study was to examine the role of the capsaicin-sensitive afferents in the process of eruption of intact rat incisors. CSPA fibers in several rat groups, were subjected to one of the following experimental procedures: systemic chemical ablation, systemic ablation followed by chemical sympathectomy and localized activation. The observed effects on incisor eruption were compared to those made on controls. The total amount of eruption in control/naïve rats, measured over a total period of 144 h, was 3.18 ± 0.07 mm and decreased to 2.43 ± 0.08 mm (n = 7; p < 0.001) following systemic ablation of CSPA. Further decrease to 2.24 ± 0.08 mm (n = 7; p < 0.001) was noticed when chemical sympathectomy was added to CSPA ablation. The average rate of eruption was 1.7 ± 0.25 mm following CSPA activation, compared to an average of 0.8 ± 0.07 mm for controls (n = 7; p < 0.001). Capsaicin sensitive fibers play an important role in tooth homeostasis, and intact neural supply is required for tooth growth under normal conditions.
KeywordsRat incisor Capsaicin Guanethidine Sympathectomy Tooth eruption Tooth innervation
Capsaicin-sensitive primary afferents
Inferior alveolar nerve
Calcitonin gene-related peptide
Prs. Nada Naaman and Nadim Mokbel (St Joseph University, School of Dental Medicine, Department of Periodontics, Beirut-Lebanon) are thanked for their help in cutting the incisors and using the microscope to take the pictures. The authors thank Bassem Najm and Sawsan Zeidan for their technical assistance. This project was supported by a Grant from the Lebanese National Council for Scientific Research (no. O/651).
Compliance with ethical standards
All experiments have been reviewed and approved by the Institutional Animal Care and Use Committee (IACUC) of the American University of Beirut under a written protocol and in accordance with the Policy on Human Care and Use of Laboratory Animals and the Guide for the Care and Use of Laboratory Animals published by the National Institutes of Health in the USA.
The animal experimental protocol in this study was approved by the Institutional Animal Care Committee, number IACUC # 16-03-466, approved on 31 March 2016.
Consent for publication
All authors have approved the manuscript and given their consent for their data to be published in the report.
Conflict of interest
The authors declare that they have no competing interests.
Availability of data
The dataset supporting the conclusions of this article is included within the article.
- Chidiac JJ, Kassab A, Rifai K, Saade NE, Al Chaer E (2018) Modulation of incisor eruption in rats by sympathetic efferents. Arch Oral Biol 89:31–36. https://doi.org/10.1016/j.archoralbio.2018.02.003
- Hayano S, Fukui Y, Kawanabe N, Kono K, Nakamura M, Ishihara Y, Kamioka H (2018) Role of the inferior alveolar nerve in rodent lower incisor stem cells. J Dent Res 97(8):954–961. https://doi.org/10.1177/0022034518758244
- Law KT, Lee CK, King NM, Rabie AB (2003) The relationship between eruption and length of mandibular incisors in young rats. Med Sci Monit 1:47–53Google Scholar
- Magloire H, Maurin JC, Couble ML, Shibukawa Y, Tsumura M, Thivichon-Prince B, Bleicher F (2010) Topical review: dental pain and odontoblasts: facts and hypotheses. J Orofac Pain 24:335–349Google Scholar
- McCafferty DM, Wallace JL, Sharkey KA (1997) Effects of chemical sympathectomy and sensory nerve ablation on experimental colitis in the rat. Am J Physiol 272(2 Pt 1):G272–G280Google Scholar
- Swiss Academy of Medical Sciences (1997) Swiss Academy of Sciences Ethical principles and guidelines for scientific experiments on animals. Altern Lab Anim 25(3):379–384Google Scholar
- Zhou Y, Long H, Ye N, Liao L, Yang X, Jian F, Wang Y (2016) The effect of capsaicin on expression patterns of CGRP in trigeminal ganglion and trigeminal nucleus caudalis following experimental tooth movement in rats. J Appl Oral Sci 24(6):597–606. https://doi.org/10.1590/1678-775720160150 CrossRefGoogle Scholar