Researchers using transparent albino Xenopus tadpoles discovered to their surprise that cannabinoids (marjuana) improved the animals ability to detect objects in low light, ie improved night vision

Researchers using transparent albino Xenopus tadpoles discovered to their surprise that cannabinoids (as in marjuana) improved the animal's ability to detect objects in low light, ie improved night vision
Photo Credit: David Freiheit.

Cannabinoids and night vision: surprising finding


It’s another somewhat serendipitous finding. Researchers in Montreal and in the US were studying the effects of marijuana (cannabinoids actually) on brain development in tadpoles and found surprisingly that it actually improved the test-animals night vision.

Edward Ruthazer (PhD) is a professor of Neurology and Neuro-surgery at the Montreal Neurological Institute at McGill University.

Professor Edward Ruthazer (PhD) led the international research effort involving scientists from Canada and the US.
Professor Edward Ruthazer (PhD) supervised the international research effort involving scientists from Canada and the US. © Neurophotonics Centre.

This latest international study led by the Ruthazer lab in Montreal was published this month in the neurological science journal, eLife Sciences (HERE)

Ruthazer says their studies often involve these albino Xenopus tadpoles. in their research because the animals are transparent and the physical changes can actually be observed as they occur.

What they found was that the chemicals in the cannabinoids apparently sensitize, or activate cells in the retina, or more specifically the chemicals increased the activity in the tadpole retinal ganglion cells (RGCs), which are responsible for transmitting information about light detection from the eye to the brain.

“We knew there was something important here”. Ruthazer

Microscopic view of the tadpole eye. The CB1 cannabinoid receptor in red and a green ganglion cell
Microscopic view of the tadpole eye. The CB1 cannabinoid receptor in red and a green ganglion cell © Dr. Lois Miraucourt.

This was contrary to common belief.  In a McGill University press release, Ruthazer said, “Initially you distrust yourself when you see something that goes against widely held ideas, but we tried the experiment so many times, using diverse techniques, and it was a consistent result. So then we knew we had to figure out what was going on. The first tendency is to want to ignore it. But it was such a strong effect, we knew there was something important here.”

The tadpoles exposed to increased levels of cannabinoids were able to detect objects in dimmer light than when they had not been exposed to the cannabinoids.

The team used software developed with McGill physics and chemistry professor Paul Wiseman to detect behavior changes in the tadpoles.

While there is anecdotal evidence that the effect occurs in humans as well, professor Ruthazer says its far too early to be certain that is the case.

He says however that with this result in tadpoles, more testing with other mammal models will likely take place

Tagged with: , , , , ,
Posted in Environment, Health, International, Internet, Science and Technology

Do you want to report an error or a typo? Click here!

@*@ Comments

Leave a Reply

Your email address will not be published. Required fields are marked *

 characters available

Note: By submitting your comments, you acknowledge that Radio Canada International has the right to reproduce, broadcast and publicize those comments or any part thereof in any manner whatsoever. Radio Canada International does not endorse any of the views posted. Your comments will be pre-moderated and published if they meet netiquette guidelines.

Netiquette »

When you express your personal opinion in an online forum, you must be as courteous as if you were speaking with someone face-to-face. Insults and personal attacks will not be tolerated. To disagree with an opinion, an idea or an event is one thing, but to show disrespect for other people is quite another. Great minds don’t always think alike—and that’s precisely what makes online dialogue so interesting and valuable.

Netiquette is the set of rules of conduct governing how you should behave when communicating via the Internet. Before you post a message to a blog or forum, it’s important to read and understand these rules. Otherwise, you may be banned from posting.

  1.’s online forums are not anonymous. Users must register, and give their full name and place of residence, which are displayed alongside each of their comments. reserves the right not to publish comments if there is any doubt as to the identity of their author.
  2. Assuming the identity of another person with intent to mislead or cause harm is a serious infraction that may result in the offender being banned.
  3.’s online forums are open to everyone, without regard to age, ethnic origin, religion, gender or sexual orientation.
  4. Comments that are defamatory, hateful, racist, xenophobic, sexist, or that disparage an ethnic origin, religious affiliation or age group will not be published.
  5. In online speak, writing in ALL CAPS is considered yelling, and may be interpreted as aggressive behaviour, which is unpleasant for the people reading. Any message containing one or more words in all caps (except for initialisms and acronyms) will be rejected, as will any message containing one or more words in bold, italic or underlined characters.
  6. Use of vulgar, obscene or objectionable language is prohibited. Forums are public places and your comments could offend some users. People who use inappropriate language will be banned.
  7. Mutual respect is essential among users. Insulting, threatening or harassing another user is prohibited. You can express your disagreement with an idea without attacking anyone.
  8. Exchanging arguments and opposing views is a key component of healthy debate, but it should not turn into a dialogue or private discussion between two users who address each other without regard for the other participants. Messages of this type will not be posted.
  9. Radio Canada International publishes contents in five languages. The language used in the forums has to be the same as the contents we publish. The usage of other languages, with the exception of some words, is forbidden. Messages that are off-topic will not be published.
  10. Making repetitive posts disrupts the flow of discussions and will not be tolerated.
  11. Adding images or any other type of file to comments is forbidden. Including hyperlinks to other websites is allowed, as long as they comply with netiquette. Radio Canada International  is in no way responsible for the content of such sites, however.
  12. Copying and pasting text written by someone else, even if you credit the author, is unacceptable if that text makes up the majority of your comment.
  13. Posting any type of advertising or call to action, in any form, to Radio Canada International  forums is prohibited.
  14. All comments and other types of content are moderated before publication. Radio Canada International  reserves the right to refuse any comment for publication.
  15. Radio Canada International  reserves the right to close a forum at any time, without notice.
  16. Radio Canada International  reserves the right to amend this code of conduct (netiquette) at any time, without notice.
  17. By participating in its online forums, you allow Radio Canada International to publish your comments on the web for an indefinite time. This also implies that these messages will be indexed by Internet search engines.
  18. Radio Canada International has no obligation to remove your messages from the web if one day you request it. We invite you to carefully consider your comments and the consequences of their posting.