Effects of 8 Hz, 90 dB infrasound on intracellular Ca2+ concentration and expression of RyRs in hippocampus of rat brain

    LIU Zhaoª²Hui1, CHEN Jingª²Zao2, TAN Yongª²Xia2, QIU Jianª²Yong2, CHEN Dan3, LIU Jing2

    1 Department of Physiotherapy & Rehabilitation, Tangdu Hospital, Xi¬ðan 710038,China,2 Department of Physiotherapy & Rehabilitation, Xijing Hospital, Xi¬ðan 710033,China, 3Department of Electron Microscope, School of Basic Medicine,Fourth Military Medical University, Xi¬ðan 710033,China

    ¡¾Abstract¡¿ AIM: To investigate the effects of infrasound on the changes of intracellular free Ca2+ concentration ([Ca2+]i) and the expression of ryanodine receptors (RyRs) in hippocampus so as to probe the mechanism of infrasonic biological effects and provide reasonable ways of sanitation protection against infrasound. METHODS: Sixty SD rats were randomized into five groups: control group, infrasound exposed groups of 1, 7, 14 and 21 d group, and then every group above was subdivided randomly into two groups to detect [Ca2+]i and the expression of RyRs, respectively. Groups exposed infrasound were put to a field with 8 Hz, 90 dB infrasound, 2 h/d. Acute cell separation, fluo-3/AM fluorescence technique and laser scanning confocal microscope were used for the measurement of intracellular free Ca2+ level, and immunohistochemical method was used for the detection of RyRs expression. RESULTS: Compared with that in control group, no significant difference of [Ca2+]i was found in 1 d and 7 d infrasonic exposure groups, but an increase of [Ca2+]i was found in 14 d group(P<0ª±01) and 21 d group(P<0ª±05). The expression of RyRs in CA1 and CA3 pyramidal cells of hippocampus had no significant difference in 1 d and 7 d infrasonic exposure groups but significant decreases was found in 14 d group(P<0ª±01)and 21 d group(P<0ª±05)compared with that in control group. The correlation coefficient between the changes of [Ca2+]i and the expression of RyRs was -0ª±977(P<0ª±01)in CA1 region and -0ª±858(P<0ª±05)in CA3 region, respectively. CONCLUSION: Infrasound at 8 Hz, 90 dB can induce[Ca2+]i increases and downª²regulate the expression of RyRs in CA1 and CA3 regions in hippocampus. These changes suggest that the increases of intracellular Ca2+ and decreases of RyRs expression in hippocampus may play a crucial role in the mechanism of learningª²memory disturbance. ......