Oxidative stress link to hearing loss

GAINESVILLE, Fla., Nov. 13 (UPI) -- U.S. researchers link oxidative stress to processes within cells that contribute to age related hearing loss.

The study, published in the Proceedings of the National Academy of Sciences, linked permanent damage to inner ear cells to oxidative damage caused when the mitochondria -- organelles within the cell that produce energy and regulate cell growth – break down and cause the release of certain proteins.

"Within the mitochondria these proteins cause life, but when they're out they're deadly," study researcher Christiaan Leeuwenburgh of the University of Florida in Gainesville said in a statement.

Leeuwenburgh and colleagues identified a protein -- Bak -- as key in the weakening of the mitochondrial membrane and found mice that were middle-aged, but Bak-deficient had hearing levels comparable to that of young mice.

When the researchers exposed the mice to a chemical that causes oxidative stress Bak deficient mice had only minor loss of inner ear cells, in contrast with the high-level of loss in the mice not deficient in the protein.