Effects of noise stress on neuronal activation in rat auditory pathway-related brain regions

Abstract

Background/Objectives: Environmental noise is a non-specific biological stressor that is becoming an escalating health concern for both industrialized and developing countries. A study by the World Health Organization identified ambient noise as the second most prevalent factor adversely affecting public health, causing high levels of stress. Extended or intense exposure to environmental noise (EN) has been linked to various alterations in auditory pathways and auditory-related central nervous system structures. We tested the hypothesis that acute exposure to intense noise could lead to such alterations. Therefore, the aim of this study is to evaluate neuronal activation in auditory-related brain regions resulting from acute noise exposure using immunohistochemistry processes. Methods: We examined a total of 12 Wistar rats (6 rats for noise exposure group; 6 rats for the control group). The noise exposure group was exposed to intense noise, while the control group experienced basal noise for thirty minutes. After scarification of the rats, tissues were collected and examined histologically using the immunohistochemical staining method. Results: Our research demonstrates that acute noise exposure markedly elevates neuronal activity in critical parts of the auditory system, such as the cochlear nuclei, inferior colliculi, trapezoid body, and primary auditory cortex. While we identified c-Fos immunoreactive neurons in the medial geniculate body of both the experiment and control groups, no statistically significant changes were found between these groups. Conclusions: These findings indicate that noise exposure-related stress could be caused primarily by the disruption of lower centers rather than the medial geniculate body.