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- Title
Nicotinic acetylcholine receptor expression by directionally selective ganglion cells.
- Authors
CHRISTIANNE E. STRANG; JORDAN M. RENNA; FRANKLIN R. AMTHOR; KENT T. KEYSER
- Abstract
Acetylcholine (ACh) enhances the preferred direction responses of directionally selective ganglion cells (DS GCs; Ariel & Daw, 1982; Ariel & Adolph, 1985) through the activation of nicotinic acetylcholine receptors (nAChRs; Ariel & Daw, 1982; Massey et al., 1997; Kittila & Massey, 1997). DS GCs appear to express at least two types of nAChRs, those that are sensitive to the partially subtype-specific antagonist methyllycaconitine (MLA), and those that are MLA-insensitive (Reed et al., 2002). Our purpose was to confirm the expression of 7 nAChRs by DS GCs and to assess the contributions of other nAChR subtypes to DS GC responses. Using choline as a nAChR partially subtype-specific agonist, we found that the majority of DS GCs demonstrated responses to choline while under synaptic blockade. The blockade or reduction of choline-induced responses by bath application of nanomolar (nM) concentrations of MLA provided direct evidence that the choline responses were mediated by 7 nAChRs. Because choline is a partial agonist for 34 nAChRs (Alkondon et al., 1997), the residual choline responses are consistent with mediation by 34 nAChRs. Additionally, a subset of DS GCs responded to nicotine but not to choline, indicating the expression of a third nAChR subtype. The pharmacological results were supported by single cell reverse transcription polymerase chain reaction (RT-PCR) and immunohistochemistry experiments. The expression of 7 and specific non-7 nAChR subtypes was correlated with the preferred direction. This indicates the possibility of differential responses to ACh depending on the direction of movement. This is the first description of differential expression of multiple nAChR subtypes by DS GCs.
- Subjects
ACETYLCHOLINE; RETINAL ganglion cells; POLYMERASE chain reaction; IMMUNOHISTOCHEMISTRY; CHOLINE
- Publication
Visual Neuroscience, 2007, Vol 24, Issue 4, p523
- ISSN
0952-5238
- Publication type
Article
- DOI
10.1017/S0952523807070435