Sex Differences in the Expression of c-fos in a Rat Brain after Exposure to Environmental Noise

Noise is an inarticulate stimulus that threatens health and well-being. It compromises audition and induces a strong stress response that activates the brain at several levels. In the present study, we expose male and female rats to environmental noise in order to investigate if acute or chronic stimulation produces differential brain activation patterns. The animals were exposed to a rat's audiogram-fitted adaptation of a noisy environment and later sacrificed to quantify the expression of the brain activity marker c-fos. Additionally, the serum corticosterone (CORT) levels were measured to elucidate possible the stress-related effects of noise. It was found that environmental noise differentially increased the serum CORT levels in male and female rats. We identified 17 brain regions outside the classical auditory circuits with a high expression of c-fos, including the hypothalamus, prefrontal cortex, habenular complex, septum, cingulate cortex, nucleus accumbens, insular cortex, amygdala, and hippocampus. Overall, we evidenced that females exhibit less intense c-fos expression in most of the examined areas. We concluded that females might be less affected by the changes produced by environmental noise.