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

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.

Neuroprotective effects of Tualang honey against oxidative stress and memory decline in young and aged rats exposed to noise stress

“…Noise exposure exceeds 90 dB has been reported to be a source of stressor [4]. The adverse impact of noise on learning, memory and hippocampal neurogenesis has been reported by previous studies [5][6][7][8][9]. The mechanisms underlying the decline of memory after noise exposure are not entirely clear.…”

Age-related learning and memory deficits in rats: role of altered brain neurotransmitters, acetylcholinesterase activity and changes in antioxidant defense system

“…The maze was elevated 60 cm high above the floor. The procedure and techniques were essentially the same as reported previously (Haider et al 2012b). The memory test was assessed during elevated plus maze experimental session in two trials (first day: learning and second day: retention of memory).…”

The Effects of Simultaneous Exposure to Styrene and Noise on Working Memory, Anxiety and Locomotor Activity in Rats

“…Husain et al reported oral intubation of styrene in male rats increased serotonin levels (32). The role of serotonin (28,33) and dopamine (21) in the pathophysiology of anxiety has been clearly proven. Phenylglyoxylic acid as one of styrene metabolite had no effects on neurobehavior after using a functional observational battery or radial arm maze and increased dopamine concentration in the cerebellum, hippocampus, pons, and whole brain (34).…”

“…The results showed that simultaneous exposure to noise and styrene decreased locomotor activity, while styrene or noise exposure alone had no significant effect on locomotor activity. Haider et al have shown that subchronic exposure to noise decreased the locomotor activity, whereas increased the concentration of dopamine in the brain and the rate of monoamine transmission (21).…”

“…Simultaneous exposure to styrene and noise decreased locomotor activity compared to the control group. Several pieces of evidence have mentioned that noise can affect the brain neurochemistry, for example, some studies have reported that exposure to noise changed the brain level of serotonin and dopamine (21,37,38). On the other hand, the impairment of turnover ratios of serotonin and dopamine has also been reported following styrene exposure (30,32).…”