Methyl mercury ototoxicity in mice determined by auditory brainstem responses

Area of Science:

• Neuroscience
• Toxicology
• Auditory Science

Background:

• Methylmercury chloride is a known neurotoxin.
• Auditory system deficits can result from toxic exposure.
• Assessing hearing function is crucial for understanding neurotoxicity.

Purpose of the Study:

• To investigate auditory deficits in C57 B1/6 mice following methylmercury chloride intoxication.
• To compare physiological auditory measurements with behavioral audibility tests.
• To determine the dose-dependent effects of methylmercury chloride on hearing.

Main Methods:

• Auditory Brainstem Responses (ABR) were recorded in mice exposed to methylmercury chloride.
• Pure-tone stimuli ranging from 4 to 78 kHz were used.
• Physiological thresholds and ABR latencies were analyzed weekly for 3 weeks post-injection.

Main Results:

• Methylmercury chloride induced auditory deficits across all tested frequencies.
• Higher frequencies exhibited a more pronounced effect of the intoxication.
• Increased ABR latencies suggested nerve conduction hypersensitivity in the brainstem.

Conclusions:

• Methylmercury chloride significantly impairs auditory function in mice.
• The auditory system, especially high-frequency hearing, is vulnerable to methylmercury toxicity.
• Brainstem auditory pathway alterations, including hypersensitivity, are observed post-intoxication.