Effect of endomorphin-2 on orofacial pain induced by orthodontic tooth movement in rats.

Abstract

Endomorphin-2 demonstrates potent antinociceptive effects in various pain models. The objectives of the present study were to explore the role of endomorphin-2 in the modulation of orofacial pain induced by orthodontic tooth movement in rats. An orthodontic pain model was established in male Sprague-Dawley rats by ligating coiled springs to mimic orthodontic force (40 g). On days 0, 1, 3, 5, 7, and 14 following orthodontic tooth movement, bite force was recorded as a surrogate measure of orthodontic pain. Ipsilateral trigeminal ganglia, trigeminal nucleus caudalis, and periodontal tissues were harvested for immunostaining. Endomorphin-2, endomorphin-2 + naloxone (a non-selective opioid receptor antagonist), naloxone, and saline were injected into trigeminal ganglia and periodontal tissues to explore the role of endomorphin-2 on orthodontic pain. The results showed that following orthodontic tooth movement, endomorphin-2 expression levels in trigeminal ganglia were elevated on days 1, 3, 5, and 7. Orthodontic pain levels were increased on days 1, 3, and 5. The administration of endomorphin-2 into both trigeminal ganglia and periodontal tissues alleviated orthodontic pain. Moreover, the effects of endomorphin-2 could be blocked by naloxone completely in trigeminal ganglia but only partially in periodontal tissues. Therefore, endomorphin-2 plays an important role in the modulation of orthodontic pain both centrally and peripherally, probably through different pathways.

• Authors: Sixin Liu, Lu Liu, Yanlu Jiang, Jing Zhou, Huimin Hu, Zhouqiang Wu, Hu Long, Wenli Lai
• Journal: European journal of oral sciences (Eur J Oral Sci) Vol. 127 Issue 5 Pg. 408-416 (10 2019) ISSN: 1600-0722 [Electronic] England
• PMID: 31365768 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: © 2019 Eur J Oral Sci.

Chemical References

• Oligopeptides
• Naloxone
• endomorphin 2

Topics

• Animals
• Facial Pain (drug therapy, etiology)
• Male
• Naloxone
• Oligopeptides (therapeutic use)
• Rats
• Rats, Sprague-Dawley
• Tooth Movement Techniques (adverse effects)
• Trigeminal Ganglion (drug effects)