Decreased Hippocampal 5-HT and DA Levels Following Sub-Chronic Exposure to Noise Stress: Impairment in both Spatial and Recognition Memory in Male Rats

Saida Haider

doi:10.3797/scipharm.1207-15

Abstract

Mankind is exposed to a number of stressors, and among them noise is one which can cause intense stress. High levels of background noise can severely impair one’s ability to concentrate. The present study was aimed to investigate the effect of sub-chronic noise stress on cognitive behavior and hippocampal monoamine levels in male rats. The study was performed on 12 male Wistar rats, divided into two groups; the control and noise-exposed. The rats in the test group were subjected to noise stress, 4h daily for 15 days. Cognitive testing was performed by the Elevated Plus Maze test (EPM) and Novel Object Recognition test (NOR). HPLC-EC was used to determine hippocampal monoamine levels and their metabolites. The data obtained revealed a significant decrease in hippocampal serotonin (5-hydroxytryptamine; 5-HT) and dopamine (DA) levels, whereas turnover ratios of 5-HT and DA were significantly increased compared to the controls. Rats exposed to noise exhibited a significant decrement in spatial memory. A significantly decreased recognition index of rats exposed to noise as compared to the control was also observed in the NOR test. Results of the present findings suggest the role of decreased hippocampal 5-HT and DA in the impairment of cognitive function following noise exposure.

Highlights

Stress is an unavoidable phenomenon that affects the body systems at various levels [1]
A significant decrease (P
The overall results of our study showed that noise exposure for 15 days altered the levels of serotonin and dopamine in the hippocampus and produced working memory and recognition memory deficits in rats

Summary

Introduction

Stress is an unavoidable phenomenon that affects the body systems at various levels [1]. Noise has a great influence on the human body [3]. Living in a noisy environment causes psychological, physiological, or behavioral changes in people, and affects sleep, work efficiency, performance, and communication ability [3, 4]. It reacts within split seconds to help the body adjust to this stressful situation by releasing hormones [2]. Researchers demonstrated that noise exposure is a potent stressor that increases the levels of the stress hormone, corticosterone [6]. Interactions between noise stress-inducing mechanisms and physiological systems involved in combating noise may lead to noise-induced illness [2]

Results

Discussion

Conclusion