May 2003
Volume 44, Issue 13
Free
ARVO Annual Meeting Abstract  |   May 2003
Nicotinic Receptor Subtype Diversity in Rabbit Retina
Author Affiliations & Notes
  • C.E. Strang
    Psychology, Univ of Alabama-Birmingham, Birmingham, AL, United States
  • J.M. Renna
    Physiological Optics, Univ of Alabama-Birmingham, Birmingham, AL, United States
  • F.R. Amthor
    Physiological Optics, Univ of Alabama-Birmingham, Birmingham, AL, United States
  • K.T. Keyser
    Physiological Optics, Univ of Alabama-Birmingham, Birmingham, AL, United States
  • Footnotes
    Commercial Relationships  C.E. Strang, None; J.M. Renna, None; F.R. Amthor, None; K.T. Keyser, None.
  • Footnotes
    Support  R01 EY07845, EY05070, P30 EY03039
Investigative Ophthalmology & Visual Science May 2003, Vol.44, 4141. doi:
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    • Get Citation

      C.E. Strang, J.M. Renna, F.R. Amthor, K.T. Keyser; Nicotinic Receptor Subtype Diversity in Rabbit Retina . Invest. Ophthalmol. Vis. Sci. 2003;44(13):4141.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Abstract: : Purpose: α3 and ß2 nicotinic acetylcholine receptor (nAChR) subunits are expressed by amacrine and ganglion cells (GCs) in the rabbit retina (Keyser et al., 2002). Additional nAChR subunits have been shown by RT-PCR (Strang et al., 2002) and by physiology (Reed et al., 2002). The purpose of the project is to identify other nAChR subunit mRNA and to explore the contribution of pharmacologically identified nAChR subtypes to the response properties of physiologically distinct GCs. Methods: For RT-PCR analysis, total RNA was extracted from retinas. Subunit-specific primers were used to amplify nAChR message and the resulting products were sequenced. Standard recording techniques were used to record light responses of GCs in an isolated retina-choroid-epithelium preparation. Either 2 µM nicotine or 400 µM choline was applied together with the subtype-specific antagonist methyllycaconitine (MLA). After recording, sharp electrodes were used to fill the cells with fluorescent dye. The retinae were fixed, cryoprotected, sectioned, and incubated with an antibody that recognizes α1, α3 and α5 nAChRs (Lindstrom, 2000). Results: Message for α3, α6, α7 and ß4 nAChR subunits was expressed in rabbit retina. Application of nicotine and choline resulted in cell-type specific excitatory and inhibitory effects on both spontaneous and light-evoked activity. The effects of choline were completely blocked by 15 nM MLA, while MLA blocked only a portion of the nicotine effects. In addition, under synaptic blockade, GCs demonstrated both MLA-sensitive and MLA-insensitive responses to agonist application. Conclusions: The MLA-sensitive choline response is likely mediated by α7 nAChRs, but may also include heteromers containing α6 subunits. The MLA-insensitive responses may be mediated by α3ß2 nAChRs but may also include heteromeric nAChRs containing ß4 subunits.

Keywords: acetylcholine • receptors: pharmacology/physiology • ganglion cells 
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