Chronic traffic noise stress accelerates brain impairment and cognitive decline in mice

• Published in: Experimental neurology 2018-10, Vol.308, p.1-12
• Main Authors: Jafari, Zahra, Kolb, Bryan E., Mohajerani, Majid H.
• Format: Article
• Language: English
• Subjects: Animals; Anxiety - etiology; Automobiles; Brain - physiopathology; Chronic stress; Cognitive Dysfunction - etiology; Cognitive Dysfunction - physiopathology; Hippocampus; HPA axis; Hypothalamo-Hypophyseal System - physiopathology; Medial prefrontal cortex; Memory; Mice; Mice, Inbred C57BL; Motor coordination; Neuronal density; Nocturnal noise; Noise, Transportation - adverse effects; Pituitary-Adrenal System - physiopathology; Prepulse inhibition; Random Allocation; Stress, Psychological - etiology; Stress, Psychological - physiopathology; Traffic noise
• ISSN: 0014-4886; 1090-2430
• DOI: 10.1016/j.expneurol.2018.06.011

Although traffic noise exposure is a well-known environmental pollutant whose negative health effect has been discussed in different aspects of the human life, only a few animal studies have tackled this issue as a cohort study, which is not feasible to be addressed in human studies. In addition to the deleterious impact of the daytime noise on well-being, chronic nocturnal noise can also disturb sleep and affects physical and mental health, but to date, little research has examined the neurobiological effects of light/dark cycles of traffic noise exposure. We investigated the effects of light/dark cycles and sex on the impact of chronic traffic noise exposure on mouse brain structure-function. The mice were randomly assigned to either one of two stress conditions or a control condition. Animals were exposed to traffic noise on either the light-cycle (LC) or dark-cycle (DC) for 30 days. Traffic noise exposure caused the hypothalamic–pituitary–adrenal (HPA) axis hyperactivity, anxiety-like behavior, impairments in learning and memory, dysfunction in balance and motor coordination, and a reduction in variety of brain measures including a brain volume, medial prefrontal cortex (mPFC) area, cortical thickness, hippocampal volume, amygdala area, and the neural density in mPFC and dentate gyrus. All behavioral and brain measures revealed adverse effects of the chronic noise stress irrespective of the LC/DC exposure or sex. Our findings were a re-emphasis on the significance of noise prevention and mitigation strategies for public health. •Chronic traffic noise stress markedly entailed the HPA axis hyperactivity.•It caused anxiety-like behavior and impairments in memory and motor coordination.•It significantly reduced neural density and brain volume in some cortical and limbic structures.•Nocturnal exposure impaired brain and behavior as large as the daytime stress.•Findings re-emphasis the significance of noise prevention and mitigation strategies for public health.