'Positive stress' helps protect eye from glaucoma

Working in mice, scientists at Washington University School of Medicine in St. Louis have devised a treatment that prevents the optic nerve injury that occurs in glaucoma, a neurodegenerative disease that is a leading cause of blindness. Researchers increased the resistance of optic nerve cells to damage by repeatedly exposing the mice to low levels of oxygen. 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. The study, published online in Molecular Medicine, is the first to show that tolerance induced by preconditioning can protect against a neurodegenerative disease. Stress is typically thought of as a negative phenomenon, but senior author Jeffrey M. Gidday and others have previously shown that the right kinds of stress, such as exercise and low-oxygen environments, can induce changes that make cells more resistant to injury and disease.