Scientists classify glaucoma as a neurodegenerative disease based on how slowly and progressively it kills retinal ganglion cells. The bodies of these cells are located in the retina of the eye; their branches or axons come together in bundles and form the optic nerves. Scientists don't know if damage begins in the bodies or axons of the cells, but as more and more retinal ganglion cells die, patients experience peripheral vision loss and eventually become blind.
For the new study, Yanli Zhu, MD, research instructor in neurosurgery, induced glaucoma in mice by tying off vessels that normally allow fluid to drain from the eye. This causes pressure in the eye to increase. Zhu then assessed how many cell bodies and axons of retinal ganglion cells were intact after three or 10 weeks.
The investigators found that normal mice lost an average of 30 percent of their retinal ganglion cell bodies after 10 weeks of glaucoma. But mice that received the preconditioning before glaucoma-inducing surgery lost only 3 percent of retinal ganglion cell bodies.
"We also showed that preconditioned mice lost significantly fewer retinal ganglion cell axons," Zhu says.
Gidday is currently investigating which genes are activated or repressed by preconditioning. He hopes to identify the changes in gene activity that make cells resistant to damage.
"Previous research has shown that there are literally hundreds of survival genes built into our DNA that are normally inactive," Gidday says. "When these genes are activated, the proteins they encode can make cells much less vulnerable to a variety of injuries."
Identifying specific survival genes should help scientists develop drugs that can activate them, according to Gidday.
Neurologis
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| Contact: Michael C. Purdy purdym@wustl.edu 314-286-0122 Washington University School of Medicine Source:Eurekalert |