Researchers increased the resistance of cells to damage by repeatedly exposing the mice to low levels of oxygen similar to those found at high altitudes. The stress of the intermittent low-oxygen environment induces a protective response called tolerance that makes nerve cells — including those in the eye — less vulnerable to harm.
Stress is typically thought of as a negative phenomenon, but senior author Jeffrey M. Gidday, PhD is the first to show that tolerance induced by preconditioning with stress can protect against a neurodegenerative disease.
For proof Gidday turned to an animal model of glaucoma, a condition linked to increases in the pressure of the fluid that fills the eye. 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.
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.
Gidday hopes his new finding will promote studies of tolerance’s potential usefulness in animal models of Parkinson’s disease, Alzheimer’s disease and other neurodegenerative conditions.