Effect of transformer noise on the neurophysiology of SD rats.

Transformer noise is a type of environmental sound that causes discomfort to individuals. The aim of the present study was to determine the effect of relatively long-term periods of transformer noise on the behavior and neurophysiology of SD rats. A total of 90 healthy SD rats with normal hearing were randomly divided into two experimental groups (65 and 60 dB group) and a control group. The experimental groups were exposed to recorded transformer noise for 8 weeks (sound level limits: 65 or 60 dB) and the control group was maintained under the same conditions without noise stimulation. Changes in physiological growth (weight tests), behavior (tail suspension and open field behavior tests) and neurophysiology (glutamate, γ-aminobutyric acid, dopamine, 5-hydroxytryptamine, the morphologies of hippocampi) following noise exposure were recorded and compared. The results revealed that rats exhibited normal physiological growth, with no significant difference between the experimental and control groups. Following noise exposure, no significant differences were observed in the results of behavioral experiments (tail suspension and open field behavior tests) between the experimental and control groups. In addition, there were no significant differences in glutamate, γ-aminobutyric acid, dopamine and 5-hydroxytryptamine levels or in the morphologies of hippocampi between groups. In conclusion, exposure to transformer noise with a sound level limit of 65 dB sound pressure level (SPL) or 60 dB SPL (spectral range, 100-800 Hz) for 8 weeks (10 h/day) had no significant impact on the behavior and neurophysiology of SD rats.