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BJ O'Brien, M Annies, H Wassle; Ionotropic Glutamate Receptors of Amacrine and Ganglion Cells in Mouse Retina . Invest. Ophthalmol. Vis. Sci. 2002;43(13):4768.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose:Ionotropic glutamate receptors (iGluRs) play a critical role in feedforward retinal pathways. The three main classes of iGluRs (AMPA, KA, NMDA) differ in their response to glutamate, exhibiting distinct kinetics, desensitization, and calcium permeability. All known iGluR subunits are expressed in the mouse retina. Due to the large number of subunits, however, it has been difficult using standard in situ hybridization or immunostaining techniques to evaluate which receptors are co-expressed in the same cells. We have used a single cell RT-PCR approach to examine the iGluR expression profiles of amacrine (AC) and ganglion cells (GC). Methods:We performed single cell multiplex RT-PCR on 68 cells harvested from slices of adult mouse retina. During whole-cell recording cells were filled with dye and classified as either ACs or GCs. Afterwards, cell content was harvested and expelled into a PCR tube. Reverse transcription of cellular mRNA was carried out overnight at 37 oC followed by multiplex PCR for 20 cycles with all iGluR primers and 35 cycles with individual primers. All cells were screened for the purity of the harvesting procedure by probing for rhodopsin, and contaminated cells (n = 29) were excluded. Results:Amacrine cells (n = 20) expressed various combinations of all 15 different iGluR subunits. The most commonly expressed subunit in ACs was GluR4 (81%) followed closely by NMDAR1 (77%). All ACs expressed one or more AMPA subunits and most (92%) co-expressed NMDA subunits. Kainate receptor subunits were expressed in 63% of ACs. In contrast, ganglion cells (n = 5) expressed only a subset of iGluRs. All GCs expressed NMDAR1 and NMDAR2A along with one or more AMPA receptors, the most common being GluR3 and GluR4 (60% each). Kainate subunits of any type were only observed in a single GC. Expression of GluR5, KA1 and NR2C subunits have so far not been observed in GCs. Conclusion:Amacrine and ganglion cells differed in their pattern of iGluR expression, in particular with respect to KA receptors. In addition, expression patterns of individual ACs and GCs varied widely, demonstrating a high degree of heterogeneity within each population, perhaps with respect to individual amacrine and ganglion cell types.
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