Pubdate: Fri, 26 Aug 2016
Source: Montreal Gazette (CN QU)
Copyright: 2016 Postmedia Network Inc.
Contact:  http://www.montrealgazette.com/
Details: http://www.mapinc.org/media/274
Author: Charlie Fidelman
Page: A3

STUDY FINDS POT IMPROVES NIGHT VISION - IN TADPOLES

Montreal researchers have found a new role for cannabinoids. The
active ingredient in marijuana - which is also naturally present in
the human body - seems to improve night vision in vertebrates.

The study by a multidisciplinary team including researchers from the
Montreal Neurological Institute looked at changes in tadpole retinas
after exposure to cannabinoids.

"We didn't believe what we were seeing - exactly the opposite of what
we expected," said neurologist Ed Ruthazer, of the Montreal
Neurological Institute of McGill University, and the paper's senior
author.

Researchers expected to find the drug would inhibit the tadpoles'
retinal ganglion cells (RGCs), which are responsible for transmitting
information about light detection from the eye to the brain.

"But the cannabinoids were increasing the excitability of cells in the
eye that connects to the brain," Ruthazer said. One class of
cannabinoid receptor, known as CB1, fired at higher frequencies
allowing the tadpoles swimming in a petri dish to see better and flee
predators in low light conditions, he explained.

Published on Aug. 8 in the journal eLife, a peer-reviewed open-access
scientific journal for biomedical and life sciences, the study adds to
the understanding of cannabinoids and brain function.

It's not known whether the same mechanism in the frog eye applies to
human eyes, Ruthazer said, however, structurally, there is an
evolutionary link.

While it's too early to say whether cannabinoids have the same effect
on mammals, and specifically human vision, some evidence in the
scientific literature suggests that it may.

Although some people find that smoking pot makes their vision fuzzy,
anecdotal evidence from a 2004 study documented an improvement in
night vision among Jamaican fishermen, and Moroccan fishermen and
mountain dwellers.

A 2014 study in rats by Pedro Lax of Alicante, Spain found the drug
protects against degeneration of the retina by preserving its cones
and rods, the structure of the eye that responds to light.

Last year on ResearchGate, a website that connects millions of
science-minded researchers, a blind Harvard University student posted
a note about her paper, Mending The Mirror, describing how marijuana
"gives me some access to vision by stimulating the endocannabinoid
system found in the retina and brain. I would like to know if
marijuana has improved the vision of others with retinal blinding
diseases," and seeking collaborators for further research on the topic.

Beyond a key role in vision, Ruthazer says he is excited his team has
discovered a previously unknown role for cannabinoids in brain
signalling. With greater focus on medical marijuana, accurate
information on how cannabinoids alter the way cells interact is
crucial, he said. The next step, he said, would be testing the
signalling mechanism in mouse models and in human retinas grown or
cultured from stem cells.

Ruthazer's study got funding from the Canadian Institutes of Health
Research, Fonds de recherche du Quebec - Sante, Epilepsie Canada, and
a Natural Sciences and Engineering Research Council CREATE
Neuroengineering Training Grant.
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MAP posted-by: Matt