Journal of Neurophysiology, Vol 72, Issue 3 1430-1433, Copyright © 1994 by APS

ARTICLES

Administration of opiate antagonist naloxone induces recurrence of increased jaw muscle activities related to inflammatory irritant application to rat temporomandibular joint region

X. M. Yu, B. J. Sessle, H. Vernon and J. W. Hu
Faculty of Dentistry, University of Toronto, Ontario, Canada.

1. Our recent studies in rats have demonstrated that the small-fiber excitant and inflammatory irritant mustard oil injected into the temporomandibular joint (TMJ) region can evoke a sustained and reversible increase of electromyographic (EMG) activity in jaw muscles and an acute inflammatory response. The aim of the present study was to test if opioid mechanisms are involved in modulating the EMG increase evoked by mustard oil. 2. Mustard oil injected into the rat TMJ region evoked significant increases of jaw muscle EMG activity; the vehicle mineral oil had no such effect. The increased EMG activity lasted up to 20 min, and by 30 min after the mustard oil injection had returned to control (preinjection) levels, at which time administration of the opiate antagonist naloxone (1.3 mg/kg i.v.) induced a significant recurrence of the increase in EMG activity. This "rekindling" of EMG activity appeared at 5 to 10 min after the naloxone administration and lasted for 10 to 20 min. In contrast, naloxone administration in the animals receiving mineral oil injection into the TMJ region did not "rekindle" the EMG activity, nor did the administration of the peripherally acting opiate antagonist methylnaloxone or the vehicle of naloxone. 3. These findings reveal that the application of the opiate antagonist naloxone produces a recurrence of increased jaw muscle activity reflexively evoked by mustard oil injection into the rat TMJ region. They suggest that central opioid depressive mechanisms activated by the mustard oil-induced afferent barrage limit the duration of the evoked EMG changes.

This article has been cited by other articles:

				Y. Guan, J. Borzan, R. A. Meyer, and S. N. Raja Windup in dorsal horn neurons is modulated by endogenous spinal mu-opioid mechanisms. J. Neurosci., April 19, 2006; 26(16): 4298 - 4307. [Abstract] [Full Text] [PDF]

				E. S. Kimball, J. M. Palmer, M. R. D'Andrea, P. J. Hornby, and P. R. Wade Acute colitis induction by oil of mustard results in later development of an IBS-like accelerated upper GI transit in mice Am J Physiol Gastrointest Liver Physiol, June 1, 2005; 288(6): G1266 - G1273. [Abstract] [Full Text] [PDF]

				D. Le Bars, M. Gozariu, and S. W. Cadden Animal Models of Nociception Pharmacol. Rev., December 1, 2001; 53(4): 597 - 652. [Abstract] [Full Text] [PDF]

				B. E. Cairns, B. J. Sessle, and J. W. Hu Characteristics of Glutamate-Evoked Temporomandibular Joint Afferent Activity in the Rat J Neurophysiol, June 1, 2001; 85(6): 2446 - 2454. [Abstract] [Full Text] [PDF]

				B. E. Cairns, B. J. Sessle, and J. W. Hu Evidence That Excitatory Amino Acid Receptors within the Temporomandibular Joint Region Are Involved in the Reflex Activation of the Jaw Muscles J. Neurosci., October 1, 1998; 18(19): 8056 - 8064. [Abstract] [Full Text] [PDF]