Rabbit retinal ganglion cells express functional α7 nicotinic acetylcholine receptors

Academic Article

Abstract

  • It is well known that cholinergic agents affect ganglion cell (GC) firing rates and light responses in the retinas of many species, but the specific receptor subtypes involved in mediating these effects have been only partially characterized. We sought to determine whether functional α7 nicotinic acetylcholine receptors (nAChRs) contribute to the responses of specific retinal GC classes in rabbit retina. We used electrophysiology, pharmacology, immunohistochemistry, and reverse transcriptase-polymerase chain reaction to determine the pharmacological properties and expression of nAChR subtypes by specific rabbit retinal GC classes. Choline was used as an α7 nAChR agonist. Methyllycaconitine (MLA) was used as a competitive α7 nAChR antagonist. The application of choline before synaptic blockade resulted in changes in retinal GC activity, including increases or decreases in maintained firing and/or enhancement or suppression of light responses. Many physiologically identified GC types, including sustained off, sustained on, transient off, and transient on cells, demonstrated responses to choline application while under synaptic blockade. The choline-induced responses could be blocked with MLA, confirming α7 nAChR activation. Individual choline-responsive GCs displayed mRNA transcripts consistent with the expression of functional α7 nAChRs. Other GCs demonstrated physiological responses and mRNA expression consistent with the expression of both α7 and non-α7 nAChRs. Thus mRNA is present for multiple nAChR subunits in whole retina extracts, and functional α7 nAChRs are capable of modulating the responses of GCs in adult rabbit retina. We also demonstrate through physiological responses that subsets of GCs express more than one nAChR subtype. Copyright © 2005 the American Physiological Society.
  • Digital Object Identifier (doi)

    Author List

  • Strang CE; Andison ME; Amthor FR; Keyser KT
  • Volume

  • 289
  • Issue

  • 3 58-3