Links found between marijuana and vision
December 7, 1999
Web posted at: 2:47 p.m. EST (1947 GMT)
WASHINGTON (Reuters) -- The active ingredient in marijuana
and hashish may affect vision by plugging into tailor-made receptors
in the eye, researchers said Monday.
They said they found the receptors -- which are chemical
doorways into cells -- in animals ranging from chicks to
salamanders to monkeys.
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This suggests that chemicals similar to the cannabinoids in
hashish and marijuana, known to occur naturally in the human
body, are ancient and highly important in eye function, the
"The fact that this system is so highly conserved in
species separated by hundreds of millions of years of evolution
suggests that it's important," Alex Straiker of the University
of California, San Diego, who led the research, said in a
'Nature likes to tinker'
"Nature likes to tinker, so any time you see something this
consistent, it raises eyebrows."
Working with colleagues at the Neurosciences Institute in
San Diego and the University of Washington in Seattle, Straiker
found cannabinoid receptors known as CB1 receptors in the
retinal cells of rhesus monkeys, chicks, salamanders, goldfish,
mice and rats.
They also occurred in both the rods and cones, which are the
eye structures that respond to light, the researchers wrote in a
report in the Proceedings of the National Academy of Sciences.
New piece to puzzle of eye function
"We understand very little about how the retina works. By
demonstrating that this receptor system is present, we add
another piece to the puzzle, opening one more window into how
the eye works," Straiker said.
"It also suggests that marijuana affects vision, because it
plugs into an existing signaling system that is abundant in the
Cannabinoids naturally occur in vertebrates. For instance,
pain triggers the release of one class of cannabinoids known as
anandamides. Anandamides are neurotransmitters, or
The chemical THC found in marijuana also is a cannabinoid.
Cannabis has been used for centuries to help relieve pain,
and some research suggests it can affect vision and also may be
able to help relieve symptoms of the eye disease glaucoma.
Researchers think THC must plug into the body's natural
system for using anandamide and other neurotransmitters.
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