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Harnessing a stress response may prevent hearing damage
Too much noise can permanently damage your hearing, but in some cases, a little noise might be just what the doctor ordered. New research from the lab of Lisa Cunningham, Ph.D., at the National Institute on Deafness and Other Communication Disorders (NIDCD) hints at a new way to protect sensory hair cells in the inner ear from potentially damaging drugs: controlled noise exposure before the drug is administered. Using noise to prevent hearing loss may seem counter to common sense, but the results from Dr. Cunningham’s lab show promise. The findings were published in the October 15, 2013 online edition of the Journal of Clinical Investigation.
Previous experiments from Dr. Cunningham’s lab indicated that protective proteins released by stressed supporting cells in the inner ear could be enlisted to protect hair cells from the damage caused by ototoxic drugs—drugs that cause hearing loss because they damage hair cells. Ototoxic drugs include helpful medicines used to treat serious infections, cancer, and heart disease. Finding a way to prevent ototoxic damage has been a goal of researchers for many years.
Scientists in other labs had shown that non-traumatic levels of noise (in other words, sound that is loud enough to stress the inner ear but not loud enough to cause hearing loss) could induce a similar protected state. To activate this stress-induced protective response, the researchers in Dr. Cunningham’s lab exposed mice to carefully-calibrated sound for 2 hours before administration of either cisplatin or kanamycin; both drugs are known to be ototoxic. Mice exposed to noise before drug administration lost significantly less hearing compared with those not exposed. This suggests that the noise exposure successfully "turned on" protective mechanisms in the ear. Accordingly, Dr. Cunningham and her colleagues are currently planning a clinical trial to test this preventive strategy in patients undergoing cisplatin chemotherapy.
“Our data definitely should not be taken as an indication that patients receiving ototoxic drugs should expose themselves to loud noises,” warns Dr. Cunningham. “We know that loud noise is a leading cause of hearing loss, and important recent studies indicate that even the levels of noise we once thought were safe may harm the inner ear. Rather, our study suggests that we might be able to provide carefully-controlled levels of sound that could be therapeutic without endangering hearing.”
The study was supported by NIDCD intramural fund DC000079.