Int J Oral Biol.  2011 Jun;36(2):71-78.

Roles of Metabotropic Glutamate Receptors 1 and 5 in Rat Medial Vestibular Nucleus Neurons

Affiliations
  • 1Department of Oral Physiology, College of Dentistry, Institute of Wonkwang Biomaterial and Implant, Wonkwang University, Iksan 570-749, Korea. physio1@wonkwang.ac.kr

Abstract

Using whole cell current- and voltage-clamp recording we investigated the characteristics and pharmacology of group I metabotropic glutamate receptor (mGluR)-mediated responses in rat medial vestibular nucleus (MVN) neurons. In current clamp conditions, activation of mGluR I by application of the group I mGluR agonist (R,S)-3,5-dihydroxyphenylglycine (DHPG) induced a direct excitation of MVN neurons that is characterized by depolarization and increased spontaneous firing frequency. To identify which of mGluR subtypes are responsible for the various actions of DHPG in MVN, we used two subtype-selective antagonists. (S)-(+)-alpha-amino-a-methylbenzeneacetic acid (LY367385) is a potent competitive antagonist that is selective for mGluR1, whereas 2-methyl-6-(phenylethynyl)-pyridine (MPEP) is a potent noncompetitive antagonist that is selective for mGluR5. In voltage clamp conditions, DHPG application increased the frequency of spontaneous and miniature inhibitory postsynaptic currents (IPSCs) but had no effect on amplitude distributions. Antagonism of the DHPG-induced increase of miniature IPSCs required the blockade of both mGluR1 and mGluR5. DHPG application induced an inward current, which can be enhanced under depolarized conditions. DHPG-induced current was blocked by LY367385, but not by MPEP. Both LY367385 and MPEP antagonized the DHPG-induced suppression of the calcium activated potassium current (IAHP). These data suggest that mGluR1 and mGluR5 have similar roles in the regulation of the excitability of MVN neurons, and show a little distinct. Furthermore, mGluR I, via pre- and postsynaptic actions, have the potential to modulate the functions of the MVN.

Keyword

medial vestibular nucleus neurons; metabotropic glutamate receptor; LY367385; MPEP; patch clamp

MeSH Terms

Animals
Benzoates
Calcium
Fires
Glycine
Inhibitory Postsynaptic Potentials
Methoxyhydroxyphenylglycol
Neurons
Potassium
Rats
Receptors, Metabotropic Glutamate
Vestibular Nuclei
Benzoates
Calcium
Glycine
Methoxyhydroxyphenylglycol
Potassium
Receptors, Metabotropic Glutamate
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