Hypothermia protects the cochlea from noise damage

Area of Science:

• Auditory Neuroscience
• Physiology
• Toxicology

Background:

• Auditory thresholds, measured by cochlear action potentials, are sensitive to body temperature.
• Noise exposure can cause permanent threshold shift (PTS), a form of hearing loss.

Purpose of the Study:

• To investigate the effect of hypothermia on auditory thresholds in rodents.
• To determine if hypothermia provides protection against noise-induced permanent threshold shift (PTS).

Main Methods:

• Cochlear action potential thresholds were measured in gerbils and mice at euthermic and hypothermic temperatures (30°C, 25°C).
• Rodents were exposed to 115 dB noise to assess permanent threshold shift (PTS).
• The protective effects of hypothermia against PTS were evaluated in both anesthetized and awake mice.

Main Results:

• Auditory thresholds increased with decreasing body temperature in both gerbils and mice across various frequencies.
• Hypothermia significantly reduced permanent threshold shift (PTS) at low and middle frequencies in anesthetized mice.
• Hypothermia also protected awake adult mice from permanent threshold shift (PTS) at their most vulnerable frequency (32 kHz).

Conclusions:

• Hypothermia elevates auditory thresholds in rodents, indicating a temperature-dependent auditory system.
• Hypothermia confers significant protection against noise-induced permanent threshold shift (PTS) in the rodent auditory system.
• These findings suggest potential therapeutic applications of controlled hypothermia in preventing noise-induced hearing loss.