Salicylic acid injection before noise exposure reduces permanent threshold shift.

The permanent threshold shift (PTS) following exposure to intense noise may be due to the noise-induced excessive vibrations in the cochlea or to the generation of elevated levels of reactive oxygen species. Thus, it is possible that the resulting PTS may be reduced if the cochlear amplifier could be temporarily depressed beginningjust before the onset of the noise and continuing during the noise exposure or if antioxidant drugs were administered. These possibilities were assessed in mice by administering a single injection of salicylic acid (an antioxidant drug which also reversibly depresses the motor protein prestin of the cochlear amplifier) just before, and in other mice, just after, 3.5 h of 113-dB SPL broadband noise exposure. The PTS in the mice injected with salicylic acid just before the noise exposure was significantly smaller than that in mice exposed to the same noise without salicylic acid. The PTS in the latter was not significantly different from that in mice who received the drug just after the noise. Thus a single injection of salicylic acid, just before a noise exposure, can protect the ear from a noise-induced hearing loss.