Influence of sex on reflex jaw muscle activity evoked from the rat temporomandibular joint

Brian E. Cairns, Yiin Sim, David A. Bereiter, Barry J. Sessle, James W. Hu

Research output: Contribution to journalArticlepeer-review

56 Scopus citations

Abstract

Injection of glutamate into the rat temporomandibular joint (TMJ) evoked a concentration-dependent increase in jaw muscle activity. We investigated whether there are sex-related differences in glutamate-evoked jaw muscle activity that are mediated by sex hormones and whether prior injection of glutamate into the TMJ alters the magnitude of jaw muscle activity evoked by a subsequent injection of the algesic and inflammatory compound mustard oil (MO) into the TMJ. The magnitude of glutamate-evoked digastric and masseter muscle activity was significantly greater in female than male rats when 1000 mM glutamate was injected into the TMJ. Gonadectomy significantly reduced the magnitude of glutamate-evoked digastric muscle activity in female rats. Treatment of gonadectomized female rats with estrogen (20 μg/day) increased the magnitude of glutamate-evoked digastric muscle activity. Glutamate-evoked jaw muscle activity in gonadectomized and estrogen-treated gonadectomized males was not significantly different from intact males. Prior injection of glutamate over a concentration range of 10-1000 mM significantly increased digastric muscle activity evoked by MO injection into the TMJ 30 min later. In contrast, MO-evoked masseter muscle activity was significantly increased by prior injection of 250 mM glutamate only. There were, however, no sex-related differences in the enhancement of MO-evoked jaw muscle activity by prior injection of glutamate. These findings indicate that there are sex-related differences in glutamate-evoked jaw muscle activity that are dependent on female sex hormones, and increased glutamate concentrations sensitize the TMJ to noxious chemical stimuli.

Original languageEnglish (US)
Pages (from-to)338-344
Number of pages7
JournalBrain Research
Volume957
Issue number2
DOIs
StatePublished - Dec 13 2002

Keywords

  • Digastric muscle
  • Excitatory amino acid
  • Masseter muscle
  • Pain
  • Temporomandibular joint
  • Trigeminal

Fingerprint Dive into the research topics of 'Influence of sex on reflex jaw muscle activity evoked from the rat temporomandibular joint'. Together they form a unique fingerprint.

Cite this