Purchase this article with an account.
C.E. Strang, M.E. Andison, F.R. Amthor, K.T. Keyser; Rabbit retinal ganglion cells express functional 7 nAChRs . Invest. Ophthalmol. Vis. Sci. 2004;45(13):4256.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Purpose: Physiological data suggest that some rabbit retinal ganglion cells express α7–like nicotinic acetylcholine receptors (nAChRs; Reed et al., 2002). In addition, functional α3ß2 nAChRs are expressed by GCs in the rabbit retina (Keyser et al., 2000; Strang et al., in press). Our purpose was to assess the contributions of distinct nAChR subtypes to the response properties of physiologically characterized GCs, and to confirm the identity of the nAChRs mediating α7–like responses. Methods: Standard extracellular recording techniques were used. Either nicotine or choline was applied with the non–specific antagonist hexamethonium bromide, or the partially specific antagonist methyllycaconitine (MLA), both before and after synaptic blockade with 2mM cobalt. Wilcoxon signed–rank tests, followed by Bonferroni corrections, were used to test significance. For RT–PCR analysis, physiologically identified cells were extracted from the retina and placed into RNAlater. In some cases sharp electrodes were used to fill the cells with fluorescent dye for morphological identification prior to extraction. α3 and α7 subunit mRNA was amplified using rabbit–specific primers, and appropriately sized RT–PCR products were sequenced to verify identity. Results: Under synaptic blockade, a subset of physiologically characterized GCs showed excitatory responses to nicotine application. Bath application of 15–30 nM MLA resulted in significant reductions in the response to nicotine, but did not abolish the nicotine response, consistent with mediation by both MLA–sensitive and MLA–insensitive nAChR subtypes. Choline was used to assess the contributions of MLA–sensitive nAChRs to GC responses. Under synaptic blockade, choline application resulted in spiking that could be blocked by bath application of 10–30nM MLA. Consistent with physiological responses, α7 and/or α3 nAChR subunit mRNA was amplified by single cell RT–PCR. Conclusions: The MLA–sensitive choline responses, together with single cell RT–PCR analysis, are consistent with the expression α7 nAChRs. These data suggest that the response properties of some GCs are mediated, at least in part, by α7 nAChRs as well as by α3–containing nAChRs.
This PDF is available to Subscribers Only