Development of endocochlear potential and its negative component in mouse cochlea

Area of Science:

• Otolaryngology
• Developmental Biology
• Auditory Physiology

Background:

• The endocochlear potential (EP) is crucial for hearing function.
• Understanding EP development is key to identifying causes of hearing impairment.

Purpose of the Study:

• To investigate the chronological development of EP and negative EP (-EP) in the basal and second cochlear turns of mice.
• To compare the developmental trajectories of EP and -EP.
• To explore the relationship between EP development and stria vascularis sensitivity to hypoxia.

Main Methods:

• Electrophysiological recordings of EP and -EP in ICR-strain mice from birth.
• Measurement of EP decline during anoxia at different ages.
• Calculation of EP decline rates.

Main Results:

• EP development in the basal turn occurred between 5 and 17 days after birth (DAB).
• -EP in the basal turn matured by 11 DAB, with further increases in absolute value between 12-16 DAB.
• Developmental patterns in the second cochlear turn mirrored the basal turn, with minor millivolt differences.
• The rate of EP decline during anoxia increased significantly around 10 DAB, coinciding with abrupt EP increases.
• Stria vascularis sensitivity to hypoxia appears to develop in parallel with EP development.

Conclusions:

• The developmental processes for positive EP and negative EP are distinct.
• EP development is closely linked to the maturation of the stria vascularis and its response to hypoxic conditions.