| Infrasound (IS) is sound wave whose frequency is lower than 20 Hz. In 1966, for the first time, the French scholar Gavreau described its property and biological effects. Infrasound is beyond human being's hearing and can only be tested by instruments. Infrasound exists widely in nature, industral and agricultural production, traffic and military affairs. It also exists in human body. With the development of industrialization, infrasound has become one of the causes of noises, which may pollute our environment. Recent studies show that infrasound with high intensity is harmful to organisms. The biological effect of infrasound is determined by frequency, sound pressure level and the time of exposure to infrasound, etc. What is more, it has something to do with the biophysical and biochemical properties of the organism itself. Studies show that the biological effect of infrasound is wide and complicated, involving several systems, organs and levels. It can not only change their structures, but also change their functions. The central nervous system plays an important role in the biological effect of infrasound. On one side, changes of the structure and function in the central nervous system could appear after exposure to infrasound, on the other side, the responses of the internal organs stimulated by infrasound may be transmitted to the central nervous system through neurohumoral system, which, after integration in the central nervous system, will further result in reflex responses of some organs and the physiological system. The fundamental mechanism of biological function is infrasound's biological resonant effect.Based on the occupational protection, 8Hz, 130dB infrasound always were used in the experiments.Studies of infrasound involve many subjects, such as military medicine, environmental medicine, basic medicine, physical medicine, public health, occupational medicine and science of biotics. Therefore, studies on the biological effect of infrasound and on hygienic protection have far-reaching significance both to the army and to the civilian. So far there have been many studies on this subject, but still there are many aspects untouched.The body is composed of elements. According to the contents of the elements in the body, they could be divided into two sorts, the macroelement and the microelement. Both of them are important to life. Because organism is also the product of environment, unconventional environment factors could affect deeply the physiology and metabolize of the organism. There are reports that some environment physical factors could bring the changes of mineral distribution.Our research focuses on the mineral distribution, the lipid peroxidation and tissue ultrastructure changes in the central nervous system after exposure to 8Hz, 130dB infrasound. In our research, the effect of infrasound on the mineral distribution in the central nervous system is initiative, no reports on which have been found both at home and abroad.This research consists of three experimental studies:Part I Changes of pallium ultrastructure after infrasound damage in rats. Objective: To study the changes and significance of cerebral ultrastructure after infrasound acts on the rats so as to probe into themechanism of the biological effects of infrasound. Methods: Thirty-five grade II male SD rats were divided into 5 groups at random: control group, 7-day infrasound damage group, 14-day infrasound damage group, 21-day infrasound damage group and 28-day infrasound damage group. The infrasound damage groups were exposed to 8 Hz, 130 dB infrasound for 2 hours once a day. 2-3 rats in each group were picked out at random. The dissected pallium from their brains was fixed with glutaraldehyde and osmic acid. The changes of the cerebral ultrastructure were observed under the transmission electron microscope (TEM). Results: Degeneration was the main change caused by infrasound in brain. It could be observed in all the structures inside and outside the brain cell. At the early stage, the damage became... |
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