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Endocannabinoid signalling improves vision in low light conditions

A new publication shows that endocannabinoid signalling improves vision in low light conditions.  This paper builds on the old anecdotal reports (from Jamaica and Morocco) that marijuana smoking helped fisherman to see better at dusk when they went out fishing. (PMID: 15182912 , PMID: 2062365 ). Researchers used a range of techniques, from electrophysiology, to calcium imaging and behavioral analysis, to show that exogenous cannabinoid ligands actually do improve vision in low light by making ganglion cells in the eye more excitable.

The researchers also showed that endogenous cannabinoids synthesized naturally in the eye can produce this effect.

Finally the team revealed that this increase in retinal ganglion cell excitability is due to a novel mechanism in which activation of the cannabinoid receptor CB1R leads to the inactivation of a chloride transporter NKCC1, resulting in an overall membrane hyperpolarization that allows cells to fire action potentials more efficiently in response to visual stimuli, effectively increasing the signal-to-noise in the retina.

Neurophotonics Centre and Platform researchers Edward Ruthazer (McGill University, lead author), Paul Wiseman (McGill Physics), and Yves De Koninck (Université Laval) co-authored this study, with collaborator Nick Marsh-Armstrong at Kennedy-Krieger (Johns-Hopkins).

Read the original research publication here:

Endocannabinoid signaling enhances visual responses through modulation of intracellular chloride levels in retinal ganglion cells
Loïs S Miraucourt Jennifer Tsui Delphine Gobert Jean-François Desjardins Anne Schohl Mari Sild Perry Spratt Annie Castonguay Yves De Koninck Nicholas Marsh-Armstrong Paul W Wiseman Edward S Ruthazer

eLife 2016;10.7554/eLife.15932

Published August 8, 2016