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Show moreThe incurable and devastating disease of age-related hearing loss (ARHL) affects a majority of the elderly worldwide. As humans age, their cells of the inner ear, which are responsible for hearing, undergo degenerative aging, as well as apoptosis (programmed cell death). Scientists believe that ARHL may be associated with specific cell types of the inner ear known to be high in mitochondrial concentration. These sensorineural tissues as well as the specific neurons, namely hair cells, spiral ganglion neurons, and cells of stria vascularis, are susceptible to irreversible cellular damage. A decline of mitochondrial function is common in various age-dependent neurodegenerative diseases. Mitochondrial health is tightly regulated by Ca2+signals, which plays an important role in ARHL. Calcium and other cations enters via mechanotransduction channels when a sound from the outside environment comes in the inner ear that cause the hair cell bundles to deflect to one side with sound frequencies. Thus, the goal of this study was to reveal the intrinsic mechanisms that relate to energy metabolism and cellular calcium balance genes expression levels in the mammalian inner ear from early development. Changes in expression of energy metabolism genes in the inner ear cells were examined in mouse models, comparing these gene expression profiles in mice ranging from embryonic day 16 to adult age of up to 4 months. Mouse models are widely used to study mammalian hearing and comprehensive databases are available. Here, databases were used to compare with preliminary data that was obtained in Dr. Ruben Stepanyan’s laboratory that had indicated the expression of mitochondrial metabolism genes can alter with age, possible affecting hearing. Once this data was obtained, it was compared on a spreadsheet and graphed using Excel. The following graphs of expression levels were made: fluorescence activated cell sorting (FACS) of all genes studied, spiral and vestibular ganglion neurons, inner and outer hair cells, and fluorescence activated cell sorting (FACS) of all the individual genes. In doing so, we were able to identify mitochondrial metabolism and cellular calcium balance-related genes that can undergo changes in expression levels in the mammalian inner ear, thus providing their importance in hearing.
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