Studies on Effects of Aircraft Noise on Behavior of Rats, Their Plasma Norepinephrine Levels and Cell Morphology of the Temporal Lobe

Abstract

To study the physiological effects of airport noise exposure on organisms, SpragueDawley (SD) rats were exposed in soundproof chambers to previously recorded aircraftrelated noise for 65 d. As a comparison, unexposed control rats were also used. According to aircraft flight schedules, aircraft noise was replayed and its weighted equivalent continuous perceived noise levels (L WECPN ) were adjusted to 75 and 80 dB for the two experimental groups. Rat behaviors were observed through an open field test and the concentrations of plasma norepinephrine (NE) were tested by high-performance liquid chromatography-fluorimetric detection (HPLC-FLD). The morphologies of neurons and synapses in the temporal lobe were also examined by transmission electron microscopy (TEM). Our results indicated that SD rats of experiment group exposed to airport noise of 80 dB had significantly lower line crossing number (P < 0.05) and significantly longer center area duration (P < 0.05) compared with that of control group. After 29 d of airport noise exposure, the concentrations of plasma NE of experiment group were significantly higher than that of control group (P < 0.05). It was determined that the neuron and synapsis of the temporal lobe of experiment group exposed to 80 dB for 65 d showed signs of damage. In conclusion, exposing rats to long-term aircraft noise affects their behaviors, plasma NE levels, and cell morphology of the temporal lobe. Of course, the differences in the hearing sensitivity to different sound frequencies and circadian rhythms between rats and humans can bring variances in physiological effects under the same noise exposure. Therefore, if this study results are applied into humans, it should be further confirmed.