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

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.

The protective effect of LY367385 on impairment of cultured mouse cerebral cortical neurons induced by sodium glutamate or oxygen-glucose deprivation / 中国康复理论与实践

@#ObjectiveTo investigate the protective effect of LY367385 on impairment of cultured mouse cerebral cortical neurons induced by sodium glutamate (Glu) or oxygen-glucose deprivation (OGD).MethodsNeuron damage induced by Glu or OGD, as well as the action of (S)-(+)-a-amino-4-carboxy-2-methylbenzeneacetic acid (LY367385) were measured by determining the leakage of lactate dehydrogenase (LDH) from neurons. Immunocytochemistry and immunofluorescent methods were used to detect the expression of anti-mGluR1α. Morphological observation of primary cortical neurons was performed by phase contrast microscope.ResultsFollowing the exposure to 0.1 mmol/L Glu for 1 h or OGD for 1 h, LDH leakage from neurons obviously increased (P< 0.01 ). 50 mmol/L LY367385, when co-incubated with Glu or OGD, markedly reduced the LDH leakage (P<0.01). The 24-h leakage of LDH was increased from cells exposed to 0.1 mmol/L Glu for 15 min. Pre-and post-treatment with LY367385 (50 mmol/L ) decreased the leakage of LDH. The cultured neurons expressed mGluR1α.ConclusionLY367385 has protective effect on neurons damaged by Glu or OGD. It may be related to antagonizing mGluR1α.