Cannabinoid receptors on goldfish retinal bipolar cells: electron-microscope immunocytochemistry and whole-cell recordings

Vis Neurosci. 2000 May-Jun;17(3):391-401. doi: 10.1017/s0952523800173079.


Cannabinoid CB1 receptors are distributed throughout the CNS and interact with GABA, glutamate, and dopamine systems. Cannabinoids have effects on the visual system, some of which may have a retinal component, particularly the enhancement of photosensitivity. We used immunocytochemistry and whole-cell recording to study cannabinoids in the goldfish retina. Immunoblots of an antiserum against amino acids (1-14) of the rat CB1 receptor produced a single band in goldfish retina at about 70 kDa. Light microscope immunocytochemistry of CB1 receptor immunoreactivity (CB1R-IR) revealed intense staining of Müller cells and weaker staining of ON bipolar cells (verified with double labeling with PKC-IR) and the outer and inner plexiform layers. Ultrastructural analysis revealed that CB1R-IR was localized intracellularly as well as on the plasma membrane of photoreceptor terminals, bipolar cell terminals and, rarely, amacrine cell boutons. Membrane-associated CB1R-IR was restricted to cone pedicles at sites removed from the synaptic ribbon. Regarding bipolar cells, membrane-associated CB1R-IR was found at 93% of the synaptic terminals in sublamina b (ON-type) and only at 33% of the synaptic terminals in sublamina a (OFF-type). Whole-cell recordings from large ON-type Mb bipolar cells showed that the delayed rectifier (I(K(V))) was rapidly and reversibly inhibited by 1 microM of the cannabinoid agonists CP 54490 and (+)-WIN 55212-2, effects blocked completely by the antagonist SR 141716A (1 microM). Inhibition of I(K(V)) in the Mb bipolar cells by cannabinoids should result in a more tonic ON response to increments of light. As such, cannabinoids may play a role in modulating the temporal aspects of signaling in the retina.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Antibodies, Monoclonal
  • Benzoxazines
  • Cannabinoids / agonists
  • Cannabinoids / antagonists & inhibitors
  • Cell Membrane / metabolism
  • Cell Membrane / ultrastructure
  • Cyclohexanols / pharmacology
  • Electrophysiology
  • Fluorescent Antibody Technique, Indirect
  • Goldfish / metabolism*
  • Immunoenzyme Techniques
  • Interneurons / drug effects
  • Interneurons / metabolism*
  • Interneurons / ultrastructure
  • Microscopy, Immunoelectron
  • Morpholines / pharmacology
  • Naphthalenes / pharmacology
  • Patch-Clamp Techniques
  • Photoreceptor Cells, Vertebrate / metabolism*
  • Photoreceptor Cells, Vertebrate / ultrastructure
  • Piperidines / pharmacology
  • Presynaptic Terminals / metabolism*
  • Presynaptic Terminals / ultrastructure
  • Pyrazoles / pharmacology
  • Receptors, Cannabinoid
  • Receptors, Drug / metabolism*
  • Rimonabant


  • Antibodies, Monoclonal
  • Benzoxazines
  • Cannabinoids
  • Cyclohexanols
  • Morpholines
  • Naphthalenes
  • Piperidines
  • Pyrazoles
  • Receptors, Cannabinoid
  • Receptors, Drug
  • (3R)-((2,3-dihydro-5-methyl-3-((4-morpholinyl)methyl)pyrrolo-(1,2,3-de)-1,4-benzoxazin-6-yl)(1-naphthalenyl))methanone
  • 3-(2-hydroxy-4-(1,1-dimethylheptyl)phenyl)-4-(3-hydroxypropyl)cyclohexanol
  • Rimonabant