Noise is not only affecting the ear and the auditory cortex locally, but its influence is widely spread throughout the brain structures, e. g., the reticular formation, the brain stem nuclei or the subcortical forebrain area. Hence, any of the organism's activities can be hindered or stimulated by noise. High noise is a stressor and the catecholamine level can be used both as a stress marker and as an indicator of modified sympathetic nervous system activity. Several recent studies have found that the urinary excretion of catecholamines is increased due to high noise intensity, especially unexpectedly high and long lasting noise. The present study was conducted in order to examine the effects of noise stress on urinary excretion of catecholamines in rats and humans. Rats were exposed to 90 dB noises for 10, 30, and 60 minutes, 3 and 12 hours. 24 hour urinary samples were collected and the catecholamines were extracted by alumina and analyzed by HPLC-ECD. Catecholamine levels increased with time of exposure up to 60 minutes: norepinephrine concentration at 60 min of noise=1.038 ng/ml, epinephrine=0.636 ng/ml. Urine catecholamines of blue collar workers exposed to 90 dB of noise at the workplace were collected between 2 and 4 p.m. and compared to that of white collar workers exposed to 70 dB. Mean norepinephrine level of the blue collar workers was 0.89 ng/ml(+/-0.25), epinephrine 0.24 ng/ml(+/-0.09), and that of the white collar workers 0.48 ng/ml(+/-0.12), epinephrine 0.19 ng/ml(+/-0.05). It was concluded that noise acts as a stressor and increases the catecholamine levels in both rats and humans.
Aluminum Oxide ; Animals ; Auditory Cortex ; Brain ; Brain Stem ; Catecholamines ; Ear ; Epinephrine ; Humans ; Noise* ; Norepinephrine ; Prosencephalon ; Rats ; Reticular Formation ; Sympathetic Nervous System