Activation of rat masticatory muscle afferent fibres by acidic pH

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Previous research findings have suggested an important role for acid sensing ion channels (ASICs) in muscle pain mechanisms. This study was conducted to determine if masticatory muscle afferent fibres express ASICs, if there are sex differences in this expression, and to compare the effects of low pH and hypertonic saline on afferent fibres that innervate the masticatory muscle in vivo. Immunohistochemistry methods were applied to examine the expression of ASICs in trigeminal ganglion neurons, while in vivo electrophysiology techniques were employed to examine changes in masticatory muscle afferent fibre excitability. Both ASIC1 and ASIC3 were expressed by predominantly larger masticatory muscle ganglion neurons, but the frequency of ASIC3 expression (56%) was significantly greater than ASIC1 (35%). No sex-related differences in expression were identified. Injection of pH 5.8, but not pH 6.8, phosphate buffered saline evoked afferent discharges that were significantly greater than those evoked by pH 7.4 buffer (control). Since ASIC3 channels are not activated until the pH is around 6, these results indicate that activation of both channels contributes to excitation of masticatory muscle afferent fibres. The results further show that many masticatory muscle afferent fibres, which respond to low pH, are low threshold mechanoreceptors. These findings may explain why injection of low pH solutions into the masticatory muscles of healthy humans is not associated with significant muscle pain.

Original languageEnglish
JournalSomatosensory and Motor Research
Volume35
Issue number2
Pages (from-to)86-94
Number of pages9
ISSN0899-0220
DOIs
Publication statusPublished - 1 Jun 2018

Fingerprint

Masticatory Muscles
Acid Sensing Ion Channels
Myalgia
Sex Characteristics
Neurons
Trigeminal Ganglion
Mechanoreceptors
Injections
Electrophysiology
Ganglia
Buffers
Immunohistochemistry
Phosphates
Research

Keywords

  • Acid sensing ion channel
  • hypertonic saline
  • immunohistochemistry
  • masticatory muscle
  • nociceptor

Cite this

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title = "Activation of rat masticatory muscle afferent fibres by acidic pH",
abstract = "Previous research findings have suggested an important role for acid sensing ion channels (ASICs) in muscle pain mechanisms. This study was conducted to determine if masticatory muscle afferent fibres express ASICs, if there are sex differences in this expression, and to compare the effects of low pH and hypertonic saline on afferent fibres that innervate the masticatory muscle in vivo. Immunohistochemistry methods were applied to examine the expression of ASICs in trigeminal ganglion neurons, while in vivo electrophysiology techniques were employed to examine changes in masticatory muscle afferent fibre excitability. Both ASIC1 and ASIC3 were expressed by predominantly larger masticatory muscle ganglion neurons, but the frequency of ASIC3 expression (56{\%}) was significantly greater than ASIC1 (35{\%}). No sex-related differences in expression were identified. Injection of pH 5.8, but not pH 6.8, phosphate buffered saline evoked afferent discharges that were significantly greater than those evoked by pH 7.4 buffer (control). Since ASIC3 channels are not activated until the pH is around 6, these results indicate that activation of both channels contributes to excitation of masticatory muscle afferent fibres. The results further show that many masticatory muscle afferent fibres, which respond to low pH, are low threshold mechanoreceptors. These findings may explain why injection of low pH solutions into the masticatory muscles of healthy humans is not associated with significant muscle pain.",
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Activation of rat masticatory muscle afferent fibres by acidic pH. / Gazerani, Parisa; Cairns, Brian Edwin.

In: Somatosensory and Motor Research, Vol. 35, No. 2, 01.06.2018, p. 86-94.

Research output: Contribution to journalJournal articleResearchpeer-review

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