Glutamate-related gene expression changes with age in the mouse auditory midbrain

Area of Science:

• Neuroscience
• Genetics
• Auditory Science

Background:

• Glutamate is the primary excitatory neurotransmitter in auditory pathways.
• Age-related hearing loss (presbycusis) may be linked to alterations in glutamate and related genes.

Purpose of the Study:

• To investigate age-related changes in glutamate-related mRNA gene expression in the mouse inferior colliculus.
• To correlate these gene expression changes with functional hearing measures.

Main Methods:

• Examined expression of 68 glutamate-related genes using genechip microarray and real-time PCR (qPCR).
• Analyzed four age/hearing loss CBA mouse groups.
• Measured auditory function using auditory brainstem response (ABR) and distortion product otoacoustic emissions (DPOAEs).

Main Results:

• Pyrroline-5-carboxylate synthetase enzyme (Pycs) mRNA expression decreased with age.
• High-affinity glutamate transporter (Slc1a3) mRNA expression increased with age and hearing loss.
• These two genes showed consistent differences across both microarray and qPCR analyses.

Conclusions:

• Pycs down-regulation may increase glutamate and decrease proline, contributing to excitotoxicity and hearing loss.
• Slc1a3 up-regulation might be a compensatory response to excitotoxicity.
• These findings highlight the role of glutamate pathway gene regulation in presbycusis.