Age-related hearing loss is mostly attributed to deterioration in the cochlea and degeneration of the auditory pathway within the brain. It is important to identify these affected regions which impair the processing of sounds. In order for the brain to interpret the sounds, they have to travel through several regions. These regions include: the ear, cochlea, auditory nerve, cochlear nucleus, superior olive, lateral lemniscus, inferior colliculus (IC), medial geniculate body (MGB) and the auditory cortex (Figure 2). The MGB is divided in several regions: dorsal, ventral and ventral subdivisions (lateral and medial). The dorsal region of the MGB relates the sound to the organism and the ventral region relays the intensity and synchronizes the sounds. Axons from the IC project into the MGB of the thalamus as the main sensory input. Vesicular Glutamate Transporters 2 (VGluT2) is a protein expressed within the IC axon terminals in all parts of the MGB (Ito et al., 2011)(1). Knowing this, we can quantify IC axon terminal present in the MGB of rat brains by comparing the dorsal region with the ventral region. While much is known about dorso-ventral differences in MGB, much less is known about lateral to medial gradients in young and aged F344 rats. For this reason, we aim to amplify our study by including the comparisons of said divisions and to determine a pattern of distribution through a Z-plane from anterior to posterior regions of the brain. Young and aged rat (F344) brains were sectioned in the coronal plane at 30 microns. These tissues were stained and 40x pictures were taken using a light microscope to analyze vGlut2 terminals in the MGB. Our expected results are that MGV vGlut2 terminals will be slightly larger than the MGD terminals. For further investigation this suggests the amplification of data to analyze in order to get more accurate results.

Quantifying vGlut2 terminals in the rat medial geniculate body

249th National Meeting (2015)

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