Effects Of High-speed Railway Noise Exposure On Neural Physiology Of The Body

For study neural physiological effects of high-speed railway noise on the body, in this paper we sampled the high-speed railway noise as well as background noise from Beijing-Tianjin inter-city railway. Then we adjust the day-night equivalent sound level (Ldn) of the railway noise for 70dB according to the schedules of train, which was consider as the experimental sound for noise exposure. ICR mice and SD whose central nervous system are similar to humans'were selected as the experiment subjects. Neurobehavioral functions of rats were tested through the commonly used animal experimental models-open field and light-dark box. The concentration of plasma neurotransmitters such as norepinephrine (NE),5-hydroxytryptamine (5-HT), dopamine (DA) and glutamic acid (Glu) were determined with the High Performance Liquid Chromatography-Fluorimetric or Enzyme Linked Immunoassay. The ultrastructure of nerve tissues in hippocampus, temporal lobe and the amygdala were observed by Transmission Electron Microscopy, and the expression of p-CaMKII protein were detected with Western Blot Method.Neurobehavioral experimental results show that, compared with control group, the desert time of mice in central field is increased (P<0.05), while cross number, grooming behavior and the frequency of standing showed no significant difference (P>0.05). In light-dark box experiments, the retention time of mice in light box and the number of lattices their crossed were significantly reduced (P<0.05) after long-term exposure to noise. The results shown that high-speed railway noise exposure produced certain negative effects on emotion and activity of mice, and the longer noise exposure duration, the more evident anxiety symptoms.The results of nerve physical measurement suggested that in the whole process of noise exposure, DA level in mice plasma were increased but shown no significant difference compare to the control group (P>0.05), and the levels of NE,5-HT and Glu in mice plasma were no significant difference compared with the control animals (P>0.05). These results shown that high-speed railway noise of 70dB have caused certain effects on plasma DA level and the effect maybe is related to depression. At the same time, this research results have speculated that high-speed railway noise of this intensity have little effect on the level of NE,5-HT and Glu in plasma of mice.The results of nerve tissue ultrastructure test showed that high-speed railway noise exposure for 90 days, karyopyknosis and margination were appeared in neurons of temporal lobe cortex and amygdala of rats, meanwhile, the number of synapses as well as synaptic vesicles and postsynaptic dense content were decreased, which may be that long-term stimulus of high-speed railway noise produced pathological damage in nerve tissue of temporal lobe cortex and amygdala. Western bloting tests showed that the expression level of p-CaMKII protein alpha and beta in temporal lobe cortex were declined significantly compared with the control rats. The results shown that rats exposure to high-speed railway noise of 70dB (Ldn) would produce adverse effect to the function of learning and memory.