Retinal metabotropic glutamate

Nakajima, Y., Iwakabe, H., Akazawa, C., el al. (1993) Molecular characterization of a novel retinal metabotropic glutamate receptor mGluR6 with a high agonist selectivity for L-2-amino-4-phosphonobutyrate. Journal of Biological Chemistry, 268, 11868-11873. 

Brandstatter JH, Koulen P, Kuhn R, Van der Putten H, Wassle H (1996) Compartmental localization of a metabotropic glutamate receptor (mGluR7) two different active sites at a retinal synapse. J Neuwsci 76 4749-4756. 

Godwin DW, Van Horn SC. Erisir A. Sesma M, Romano C, Sherman SM (1996) Ultrastructural localization suggests that retinal and cortical inputs access different metabotropic glutamate receptors in the lateral geniculate nucleus. J Neurosci /d 8181-8192. 

Glutamate s role as a neurotransmitter in the vertebrate retina is reviewed by Barnstable (1993), Brandstatter et al. (1998) and Lo et al. (1998). As the cell bodies of different retinal cell types are in different laminae (Fig. 10), we can assign which general cell types express which glutamate receptor subunits. However, there are different subsets of the same cell class, e.g., there are at least 10 different types of on- and off-bipolars, and multiple subtypes of the other cell classes (Stevens, 1998). Without cell-type markers and double-labelling studies, ISH can not differentiate these. The cones and rods release glutamate onto the bipolar cells only off-bipolars use ionotropic receptors at this synapse on-bipolars use the metabotropic receptor mGluR6 instead. The distribution of NMDA and non-NMDA receptor mRNAs in the retina is summarized in Fig. 10. 

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