Journal of Neurophysiology, Vol 63, Issue 2 356-369, Copyright © 1990 by APS

ARTICLES

An iontophoretic analysis of the pharmacologic mechanisms responsible for trigeminal motoneuronal discharge during masticatory-like activity in the guinea pig

N. Katakura and S. H. Chandler
Department of Kinesiology, Brain Research Institute, University of California, Los Angeles 90024.

1. The effects of iontophoretic application of the excitatory amino acid antagonists kynurenic acid (KYN) and DL-2-amino-5-phosphonovaleric acid (APV), as well as the monoamines serotonin (5-HT) and norepinephrine (NE), on extracellularly recorded jaw opener motoneuron [digastric motoneuron (DIG)] discharge during cortically induced rhythmical masticatory-like activity (RMA) were examined in the anesthetized guinea pig. 2. Iontophoretic application of KYN, a broad-spectrum amino acid antagonist, suppressed the motoneuronal discharge evoked by short pulse train stimulation of the cortex for most cells tested. In contrast, iontophoretic application of APV, a specific N-methyl-D-aspartate (NMDA) antagonist, was usually without effect on the motoneuronal discharge evoked by short pulse train stimulation. 3. During RMA evoked by repetitive cortical stimulation, both KYN and APV suppressed rhythmical DIG motoneuronal discharge in many cells tested. 4. These data suggest that excitatory amino acid receptors on jaw opener motoneurons are involved in activation of RMA. It is proposed that the short-latency rapid excitation of jaw opener motoneurons, which occurs during both short pulse train cortical stimulation and RMA induced by repetitive cortical stimulation, is mediated, at least in part, by non-NMDA receptors. It is further suggested that the large-amplitude, long-duration slow rhythmical oscillations, which occur in the membrane potential of jaw opener motoneurons during RMA induced by repetitive cortical stimulation, are mediated, at least in part, by NMDA receptors. 5. Iontophoretic application of NE or 5-HT with low currents (less than 20 nA) produced a facilitation of digastric motoneuronal discharge during cycle-triggered glutamate application, short pulse train cortical stimulation, and RMA evoked by repetitive cortical stimulation. These facilitatory effects on motoneuronal discharge started within 1 min of drug application, reached a peak at approximately 3 min that persisted for several minutes after the application period, and recovered to control levels within 10-15 min. Direct application of NE or 5-HT, in the absence of chemical or synaptic activation, failed to activate these motoneurons. However, iontophoretic application of either monoamine could facilitate and bring to threshold rhythmical motoneuronal discharges during subthreshold repetitive cortical stimulation. 6. Iontophoretic application of methysergide, a 5-HT antagonist, and phentolamine, an alpha adrenoreceptor blocker, both produced a selective and reversible blockade of the facilitatory effects of 5-HT and NE, respectively, on motoneuronal discharge during cortically induced RMA. In contrast, iontophoretic application of sotalol, a beta adrenoreceptor blocker, had no effect on the NE-induced facilitation of RMA.(ABSTRACT TRUNCATED AT 400 WORDS)

This article has been cited by other articles:

				N. P. Cramer and A. Keller Cortical Control of a Whisking Central Pattern Generator J Neurophysiol, July 1, 2006; 96(1): 209 - 217. [Abstract] [Full Text] [PDF]

				C.-F. Hsiao, N. Wu, and S. H. Chandler Voltage-Dependent Calcium Currents in Trigeminal Motoneurons of Early Postnatal Rats: Modulation by 5-HT Receptors J Neurophysiol, September 1, 2005; 94(3): 2063 - 2072. [Abstract] [Full Text] [PDF]

				Z. Chen and J. B. Travers Inactivation of amino acid receptors in medullary reticular formation modulates and suppresses ingestion and rejection responses in the awake rat Am J Physiol Regulatory Integrative Comp Physiol, July 1, 2003; 285(1): R68 - R83. [Abstract] [Full Text] [PDF]

				P. Fenik and S. C. Veasey Pharmacological Characterization of Serotonergic Receptor Activity in the Hypoglossal Nucleus Am. J. Respir. Crit. Care Med., February 15, 2003; 167(4): 563 - 569. [Abstract] [Full Text] [PDF]

				A. Mori, M. Kogo, K. Ishihama, S. Tanaka, A. Enomoto, H. Koizumi, and T. Matsuya Effect of Serotonin (5-HT) on Trigeminal Rhythmic Activities Generated in in vitro Brainstem Block Preparations Journal of Dental Research, September 1, 2002; 81(9): 598 - 602. [Abstract] [Full Text] [PDF]

				C.-F. Hsiao, N. Wu, M. S. Levine, and S. H. Chandler Development and Serotonergic Modulation of NMDA Bursting in Rat Trigeminal Motoneurons J Neurophysiol, March 1, 2002; 87(3): 1318 - 1328. [Abstract] [Full Text] [PDF]

				K.E. Byrd and T.A. Sheskin Effects of Post-natal Serotonin Levels on Craniofacial Complex Journal of Dental Research, August 1, 2001; 80(8): 1730 - 1735. [Abstract] [PDF]

				J. C. Rekling, G. D. Funk, D. A. Bayliss, X.-W. Dong, and J. L. Feldman Synaptic Control of Motoneuronal Excitability Physiol Rev, April 1, 2000; 80(2): 767 - 852. [Abstract] [Full Text] [PDF]

				T. Inoue, S. Itoh, M. Kobayashi, Y. Kang, R. Matsuo, S. Wakisaka, and T. Morimoto Serotonergic Modulation of the Hyperpolarizing Spike Afterpotential in Rat Jaw-Closing Motoneurons by PKA and PKC J Neurophysiol, August 1, 1999; 82(2): 626 - 637. [Abstract] [Full Text] [PDF]

				C. A. Del Negro and S. H. Chandler Regulation of Intrinsic and Synaptic Properties of Neonatal Rat Trigeminal Motoneurons by Metabotropic Glutamate Receptors J. Neurosci., November 15, 1998; 18(22): 9216 - 9226. [Abstract] [Full Text] [PDF]

				C.-F. Hsiao, C. A. D. Negro, P. R. Trueblood, and S. H. Chandler Ionic Basis for Serotonin-Induced Bistable Membrane Properties in Guinea Pig Trigeminal Motoneurons J Neurophysiol, June 1, 1998; 79(6): 2847 - 2856. [Abstract] [Full Text] [PDF]

				K.E. Byrd, M.J. Sukay, M.W. Dieterle, L. Yang, T.C. Marting, D. Teomim, and A.J. Domb Craniofacial and TMJ Effects after Glutamate and TRH Microsphere Implantation in Proximity to Trigeminal Motoneurons of Growing Rats Journal of Dental Research, August 1, 1997; 76(8): 1437 - 1452. [Abstract] [PDF]

				C. F. Hsiao, P. R. Trueblood, M. S. Levine, and S. H. Chandler Multiple Effects of Serotonin on Membrane Properties of Trigeminal Motoneurons In Vitro J Neurophysiol, June 1, 1997; 77(6): 2910 - 2924. [Abstract] [Full Text] [PDF]

				J.P. Lund Mastication and its Control by the Brain Stem Critical Reviews in Oral Biology & Medicine, January 1, 1991; 2(1): 33 - 64. [Abstract] [Full Text] [PDF]