Noise Stress Induces an Epidermal Growth Factor Receptor/Xeroderma Pigmentosum–A Response in the Auditory Nerve

Abstract

SummaryIn response to toxic stressors, cancer cells defend themselves by mobilizing one or more epidermal growth factor receptor (EGFR) cascades that employ xeroderma pigmentosum-A (XPA) to repair damaged genes. Recent experiments discovered that neurons within the auditory nerve exhibit basal levels of EGFR+XPA co-expression. This finding implied that auditory neurons in particular or neurons in general have the capacity to mobilize an EGFR+XPA defense. Therefore, the current study tested the hypothesis that noise stress would alter the expression pattern of EGFR/XPA within the auditory nerve. Design-based stereology was used to quantify the proportion of neurons that expressed EGFR, XPA, and EGFR+XPA with and without noise stress. The results revealed an intricate neuronal response that is suggestive of alterations to both co-expression and individual expression of EGFR and XPA. In both the apical and middle cochlear coils, the noise stress depleted EGFR+XPA expression. Furthermore, there was a reduction in the proportion of neurons that expressed XPA-alone in the middle coils. However, the noise stress caused a significant increase in the proportion of neurons that expressed EGFR-alone in the middle coils. The basal cochlear coils failed to mobilize a significant response to the noise stress. These results suggest that EGFR and XPA might be part of the molecular defense repertoire of the auditory nerve. (J Histochem Cytochem 65:173-184, 2017)

Nondeterministic nature of sensorineural outcomes following noise trauma

“…Therefore, it appears that both noise exposure and genotype are necessary, but neither is sufficient to explain variability in hearing thresholds following noise exposure ( Carlsson et al, 2005 ). More direct factors that are often overlooked (yet influenced by both noise exposure and genotype), are the various cellular and subcellular changes which ultimately affect the physiological state of the organ ( Guthrie, 2012 , 2017 ; Guthrie and Xu, 2012 ; Xia et al, 2013 ). Such change in physiology is nondeterministic and expected to manifest various forms.…”