Phosphorylation of p38 in Trigeminal Ganglion Neurons Contributes to Tongue Heat Hypersensitivity in Mice

Aims: To develop a tongue pain model with no mucosal pathologic changes and to examine whether phosphorylation of p38 in trigeminal ganglion (TG) neurons innervating the tongue is associated with tongue heat hypersensitivity in mice. Methods: Tongue heat sensitivity in mice was assessed following application of the irritant 2,4,6-trinitrobenzene sulfonic acid (TNBS) to the tongue. After TNBS application, the expressions of p38, phosphorylated p38 (pp38), and transient receptor potential vanilloid 1 (TRPV1) were examined in TG neurons innervating the tongue. To further assess changes in tongue heat sensitivity and TRPV1 expression, a specific inhibitor of p38 phosphorylation (SB203580) was also administered into the TG. Student t test or two-way repeated-measures analysis of variance followed by Sidak multiple comparison test were used for statistical analysis, and P < .05 was considered statistically significant. Results: TNBS application to the tongue induced noninflammatory heat hypersensitivity accompanied by the enhancement of p38 phosphorylation in TG neurons innervating the tongue and by an increase in the number of TRPV1 and pp38–immunoreactive (IR) TG neurons innervating the tongue. Intra-TG administration of SB203580 suppressed the increase in the TRPV1 and pp38–IR TG neurons and alleviated the noninflammatory tongue heat hypersensitivity induced by TNBS. Conclusion: p38 signaling cascades are involved in tongue heat hyperalgesia in association with TRPV1 upregulation in TG neurons innervating the TNBS-treated tongue.

burning mouth syndrome; heat hyperalgesia; mitogen-activated protein kinase; transient receptor potential vanilloid 1; trigeminal ganglion

1. Grushka M. Clinical features of burning mouth syndrome. Oral Surg Oral Med Oral Pathol 1987;63:30–36.

2. Klasser GD, Grushka M, Su N. Burning mouth syndrome. Oral Maxillofac Surg Clin North Am 2016;28:381–396.

3. López-Jornet P, Camacho-Alonso F, Andujar-Mateos P, Sánchez-Siles M, Gómez-Garcia F. Burning mouth syndrome: An update. Med Oral Patol Oral Cir Bucal 2010;15:e562–e568.

4. Grushka M, Sessle BJ. Burning mouth syndrome. Dent Clin North Am 1991;35:171–184.

5. Katagiri A, Shinoda M, Honda K, Toyofuku A, Sessle BJ, Iwata K. Satellite glial cell P2Y12 receptor in the trigeminal ganglion is involved in lingual neuropathic pain mechanisms in rats. Mol Pain 2012;8:23.

6. Suzuki A, Shinoda M, Honda K, Shirakawa T, Iwata K. Regulation of transient receptor potential vanilloid 1 expression in trigeminal ganglion neurons via methyl-CpG binding protein 2 signaling contributes tongue heat sensitivity and inflammatory hyperalgesia in mice. Mol Pain 2016;12.

7. Lauria G, Majorana A, Borgna M, et al. Trigeminal small-fiber sensory neuropathy causes burning mouth syndrome. Pain 2005; 115:332–337.

8. Yilmaz Z, Renton T, Yiangou Y, et al. Burning mouth syndrome as a trigeminal small fibre neuropathy: Increased heat and capsaicin receptor TRPV1 in nerve fibres correlates with pain score. J Clin Neurosci 2007;14:864–871.

9. Laedermann CJ, Abriel H, Decosterd I. Post-translational modifications of voltage-gated sodium channels in chronic pain syndromes. Front Pharmacol 2015;6:263.

10. Ma W, Quirion R. The ERK/MAPK pathway, as a target for the treatment of neuropathic pain. Expert Opin Ther Targets 2005; 9:699–713.

11. Ji RR, Gereau RW 4th, Malcangio M, Strichartz GR. MAP kinase and pain. Brain Res Rev 2009;60:135–148.

12. Widmann C, Gibson S, Jarpe MB, Johnson GL. Mitogen-activated protein kinase: Conservation of a three-kinase module from yeast to human. Physiol Rev 1999;79:143–180.

13. Turjanski AG, Vaqué JP, Gutkind JS. MAP kinases and the control of nuclear events. Oncogene 2007;26:3240–3253.

14. Hudmon A, Choi JS, Tyrrell L, et al. Phosphorylation of sodium channel Na(v)1.8 by p38 mitogen-activated protein kinase increases current density in dorsal root ganglion neurons. J Neurosci 2008;28:3190–3201.

15. Black JA, Nikolajsen L, Kroner K, Jensen TS, Waxman SG. Multiple sodium channel isoforms and mitogen-activated protein kinases are present in painful human neuromas. Ann Neurol 2008;64:644–653.

16. Deiteren A, De Man JG, Ruyssers NE, Moreels TG, Pelckmans PA, De Winter BY. Histamine H4 and H1 receptors contribute to postinflammatory visceral hypersensitivity. Gut 2014;63: 1873–1882.

17. Shinoda M, Takeda M, Honda K, et al. Involvement of peripheral artemin signaling in tongue pain: Possible mechanism in burning mouth syndrome. Pain 2015;156:2528–2537.

18. Zimmermann M. Ethical guidelines for investigations of experimental pain in conscious animals. Pain 1983;16:109–110.

19. Grushka M, Sessle BJ, Miller R. Pain and personality profiles in burning mouth syndrome. Pain 1987;28:155–167.

20. Liu MG, Matsuura S, Shinoda M, et al. Metabotropic glutamate receptor 5 contributes to inflammatory tongue pain via extracellular signal-regulated kinase signaling in the trigeminal spinal subnucleus caudalis and upper cervical spinal cord. J Neuroinflammation 2012;9:258.

21. Sugiyo S, Uehashi D, Satoh F, et al. Effects of systemic bicuculline or morphine on formalin-evoked pain-related behaviour and

c- Fos expression in trigeminal nuclei after formalin injection into the lip or tongue in rats. Exp Brain Res 2009;196:229–237.

22. Kolkka-Palomaa M, Jääskeläinen SK, Laine MA, Teerijoki-Oksa T, Sandell M, Forssell H. Pathophysiology of primary burning mouth syndrome with special focus on taste dysfunction: A review. Oral Dis 2015;21:937–948.

23. Forssell H, Svensson P. Chapter 39 atypical facial pain and burning mouth syndrome. Handb Clin Neurol 2006;81:597–608.

24. Obata K, Noguchi K. MAPK activation in nociceptive neurons and pain hypersensitivity. Life Sci 2004;74:2643–2653.

25. Woolf CJ, Safieh-Garabedian B, Ma QP, Crilly P, Winter J. Nerve growth factor contributes to the generation of inflammatory sensory hypersensitivity. Neuroscience 1994;62:327–331.

26. Ji RR, Samad TA, Jin SX, Schmoll R, Woolf CJ. p38 MAPK activation by NGF in primary sensory neurons after inflammation increases TRPV1 levels and maintains heat hyperalgesia. Neuron 2002;36:57–68.

27. Cheng HT, Dauch JR, Oh SS, Hayes JM, Hong Y, Feldman EL. p38 mediates mechanical allodynia in a mouse model of type 2 diabetes. Mol Pain 2010;6:28.

28. Evangelisti C, Bianco F, Pradella LM, et al. Apolipoprotein B is a new target of the GDNF/RET and ET-3/EDNRB signalling pathways. Neurogastroenterol Motil 2012;24:e497–e508.

29. Zelenka M, Schäfers M, Sommer C. Intraneural injection of interleukin-1beta and tumor necrosis factor-alpha into rat sciatic nerve at physiological doses induces signs of neuropathic pain. Pain 2005;116:257–263.

30. Binshtok AM, Wang H, Zimmermann K, et al. Nociceptors are interleukin-1beta sensors. J Neurosci 2008;28:14062–14073.

31. Eijkelkamp N, Heijnen CJ, Carbajal AG, et al. G protein-coupled receptor kinase 6 acts as a critical regulator of cytokine-induced hyperalgesia by promoting phosphatidylinositol 3-kinase and inhibiting p38 signaling. Mol Med 2012;18:556–564.

32. Jin X, Gereau RW 4th. Acute p38-mediated modulation of tetrodotoxin-resistant sodium channels in mouse sensory neurons by tumor necrosis factor-alpha. J Neurosci 2006;26: 246–255.

33. Gudes S, Barkai O, Caspi Y, Katz B, Lev S, Binshtok AM. The role of slow and persistent TTX-resistant sodium currents in acute tumor necrosis factor-alpha-mediated increase in nociceptors excitability. J Neurophysiol 2015;113:601–619.

34. Tominaga M, Caterina MJ. Thermosensation and pain. J Neurobiol 2004;61:3–12.

35. Julius D. TRP channels and pain. Annu Rev Cell Dev Biol 2013; 29:355–384.

36. Xu H, Blair NT, Clapham DE. Camphor activates and strongly desensitizes the transient receptor potential vanilloid subtype1 channel in a vanilloid-independent mechanism. J Neurosci 2005;25:8924–8937.

37. Zygmunt PM, Petersson J, Andersson DA, et al. Vanilloid receptors on sensory nerves mediate the vasodilator action of anandamide. Nature 1999;400:452–457.

38. Huang SM, Bisogno T, Trevisani M, et al. An endogenous capsaicin-like substance with high potency at recombinant and native vanilloid VR1 receptors. Proc Natl Acad Sci U S A 2002; 99:8400–8405.

39. Urata K, Shinoda M, Honda K, et al. Involvement of TRPV1 and TRPA1 in incisional intraoral and extraoral pain. J Dent Res 2015; 94:446–454.

40. Jankowski MP, Soneji DJ, Ekmann KM, Anderson CE, Koerber HR. Dynamic changes in heat transducing channel TRPV1 expression regulate mechanically insensitive, heat sensitive C-fiber recruitment after axotomy and regeneration. J Neurosci 2012; 32:17869–17873.

41. Lee JC, Laydon JT, McDonnell PC, et al. A protein kinase involved in the regulation of inflammatory cytokine biosynthesis. Nature 1994;372:739–746.

42. Kumar S, Boehm J, Lee JC. p38 MAP kinases: Key signalling molecules as therapeutic targets for inflammatory diseases. Nat Rev Drug Discov 2003;2:717–726.

43. Ikeda-Miyagawa Y, Kobayashi K, Yamanaka H, et al. Peripherally increased artemin is a key regulator of TRPA1/V1 expression in primary afferent neurons. Mol Pain 2015;11:8.

44. Kaji K, Shinoda M, Honda K, Unno S, Shimizu N, Iwata K. Connexin 43 contributes to ectopic orofacial pain following inferior alveolar nerve injury. Mol Pain 2016;12.

45. Matsuura S, Shimizu K, Shinoda M, et al. Mechanisms underlying ectopic persistent tooth-pulp pain following pulpal inflammation. PLoS One 2013;8:e52840.

46. Nakaya Y, Tsuboi Y, Okada-Ogawa A, et al. ERK-GluR1 phosphorylation in trigeminal spinal subnucleus caudalis neurons is involved in pain associated with dry tongue. Mol Pain 2016;12.