Modulatory effects mediated by metabotropic glutamate receptor 5 on lateral geniculate nucleus relay cells
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Modulatory effects mediated by metabotropic glutamate receptor 5 on lateral geniculate nucleus relay cellsFecha
2005-01-18Cita bibliográfica
Labra C, Rivadulla C, Cudeiro J. Modulatory effects mediated by metabotropic glutamate receptor 5 on lateral geniculate nucleus relay cells. Eur J Neurosci. 2005;21:403-10.
Resumen
[Abstract] Glutamate is thought to be the excitatory neurotransmitter in the lateral geniculate nucleus (LGN) of the cat, mediating visual transmission from the retina via ionotropic receptors of both d,l-α-amino-3-hydroxy-5-α-methyl-4-isoxazolepropionate and N-methyl-d-aspartate subtypes. Moreover, glutamate also exerts an important modulatory influence on LGN cells, where metabotropic glutamate receptors (mGluRs) seem to play a crucial role. Here we show in anesthetized adult cats that iontophoretic application of the specific mGluR5 antagonist 2-methyl-6-(phenylethynyl)-pyridine (MPEP) produced two, distinctly different, effects on LGN neurons. Visual responses to flashing spots and drifting gratings were attenuated (decreased by an average of 59%) in 13 of 23 of the cells but augmented (increased by an average of 60%) in 10 of 23 of the cells. Further, in each case when the specific mGluR5 agonist (R,S)-2-chloro-5-hydroxyphenylglycine was applied, the effects obtained were the opposite to those of MPEP. Data obtained in a second group of experiments to determine a possible interaction between mGluR5 blockade by MPEP and glutamate ionotropic receptors show that, in the majority of neurons (11 of 15, 73%), the MPEP-mediated effects seem to be independent of N-methyl-d-aspartate and d,l-α-amino-3-hydroxy-5-α-methyl-4-isoxazolepropionate receptor activity. Our results demonstrate a physiological role for mGluR5 in controlling retinal input and show, in vivo, a more intricate scenario than previously suggested, highlighting the complexity of metabotropic receptor interactions with excitatory and inhibitory elements in the thalamus.
Palabras clave
Cat
Glutamate
Metabotropic receptors
2-methyl-6-(phenylethynyl)-pyridine
Retinal input
Vision
Glutamate
Metabotropic receptors
2-methyl-6-(phenylethynyl)-pyridine
Retinal input
Vision
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This is a peer reviewed version of the article which has been published in the final form at Wiley Online Library. This article may be used for non-commercial purposes in accordance With Wiley Terms and Conditions for self-archiving.