Bipolar Cell Type-Specific Expression and Conductance of Alpha-7 Nicotinic Acetylcholine Receptors in the Mouse Retina

Invest Ophthalmol Vis Sci. 2019 Apr 1;60(5):1353-1361. doi: 10.1167/iovs.18-25753.


Purpose: Motion detection is performed by a unique neural network in the mouse retina. Starburst amacrine cells (SACs), which release acetylcholine and gamma-aminobutyric acid (GABA) into the network, are key neurons in the motion detection pathway. Although GABA contributions to the network have been extensively studied, the role of acetylcholine is minimally understood. Acetylcholine receptors are present in a subset of bipolar, amacrine, and ganglion cells. We focused on α7-nicotinic acetylcholine receptor (α7-nAChR) expression in bipolar cells, and investigated which types of bipolar cells possess α7-nAChRs.

Methods: Retinal slice sections were prepared from C57BL/6J and Gus8.4-GFP mice. Specific expression of α7-nAChRs in bipolar cells was examined using α-bungarotoxin (αBgTx)-conjugated Alexa dyes co-labeled with specific bipolar cell markers. Whole-cell recordings were conducted from bipolar cells in retinal slice sections. A selective α7-nAChR agonist, PNU282987, was applied by a puff and responses were recorded.

Results: αBgTx fluorescence was observed primarily in bipolar cell somas. We found that α7-nAChRs were expressed by the majority of type 1, 2, 4, and 7 bipolar cells. Whole-cell recordings revealed that type 2 and 7 bipolar cells depolarized by PNU application. In contrast, α7-nAChRs were not detected in most of type 3, 5, 6, and rod bipolar cells.

Conclusions: We found that α7-nAChRs are present in bipolar cells in a type-specific manner. Because these bipolar cells provide synaptic inputs to SACs and direction selective ganglion cells, α7-nAChRs may play a role in direction selectivity by modulating these bipolar cells' outputs.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Benzamides / pharmacology
  • Bridged Bicyclo Compounds / pharmacology
  • Mice
  • Mice, Inbred C57BL
  • Models, Animal
  • Motion Perception / physiology
  • Nicotinic Agonists / pharmacology
  • Retinal Bipolar Cells / metabolism*
  • Synaptic Transmission / physiology*
  • alpha7 Nicotinic Acetylcholine Receptor / antagonists & inhibitors
  • alpha7 Nicotinic Acetylcholine Receptor / metabolism*


  • Benzamides
  • Bridged Bicyclo Compounds
  • Nicotinic Agonists
  • PNU-282987
  • alpha7 Nicotinic Acetylcholine Receptor