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Wed, May 18, 2005
Visionary discovery
Local scientists' finding changes way experts see retina
In science's ultimate goal of rebuilding a retina to restore vision, Ottawa scientists have found a crucial building block.
It wasn't something they went looking for. They stumbled across it.
The team in Dr. Rashmi Kothary's lab at the Ottawa Hospital Research Institute set out to examine the retinal function of a mouse paralyzed by a neurological disorder caused by a mutation in the Scn8a gene, which controls electrical nerve impulses.
RECEPTORS NOT WORKING
To determine what was going on in the mouse's central nervous system, researchers looked at its retina, which offers a window into the rest of the brain.
They realized that not only had this mouse been paralyzed, it was blind. Its photoreceptors, which capture light, were not working.
That surprised researchers because photoreceptors, unlike almost every other nerve cell, use analog signals to communicate. Others use "digital" or binary signals, and need the Scn8a gene.
Given the mouse's paralyzed state, researchers knew the gene wasn't present. But they now know the gene also plays a role in the ability of photoreceptors to communicate, which in turn allows for vision.
When it's not there during development, it appears all cells in the retina are unable to talk to one another and develop as they should.
"This was completely unexpected. It adds a layer of complexity," said Dr. Patrice Cote, a senior postdoctoral fellow.
While this may not mean much to the average person, Cote said it's important. While every researcher finds a piece of the puzzle, this amounts to a "pretty significant piece."
"It's a basic finding, but it kind of changes the way we see vision -- our concept of how the retina develops," he said. "Our ultimate goal is to be able to rebuild a new retina. So the normal things we find, they can give us a map in terms of how to rebuild a retina."
Basically, if you want to rebuild a retina, you have to understand how it works. This discovery aids in that understanding.
'OPENS THE DOOR'
Cote said rebuilding is science's long-term goal because as people age, photoreceptors degenerate, leading to vision loss. Since the retina is part of the brain, once those cells are gone, they're gone for good.
"This opens the door to a lot more research," Cote said. "We need to figure out what's going on here."
That question will form the basis of the lab he's starting this summer in Halifax. Meanwhile, the findings appear in this week's Journal of Neuroscience.
holly.lake@ott.sunpub.com