| Project/Area Number |
09650483
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
計測・制御工学
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| Research Institution | Hiroshima City University |
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Principal Investigator |
HIWAKI Osamu Hiroshima City University, Faculty of Information Sciences, Associate Professor, 情報科学部, 助教授 (30264948)
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| Project Period (FY) |
1997 – 1998
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| Project Status |
Completed (Fiscal Year 1998)
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| Budget Amount *help |
¥3,200,000 (Direct Cost: ¥3,200,000)
Fiscal Year 1998: ¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1997: ¥1,300,000 (Direct Cost: ¥1,300,000)
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| Keywords | Magnetic Field / Suprachiasmatic Nucleus / Biological Clock / Melatonin / Circadian Rhythm / 商用周波数 / 慨日リズム |
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| Research Abstract |
Some reports have shown that the5O Hz magnetic field could suppress the nocturnal melatonin secretion in the pineal gland. The sympathetic neurons that innervate the pineal gland are driven by the intrinsic activity of the biological clock, known as the suprachiasmatic nucleus (SCN). The study reported here is the first attempt to investigate whether the 50Hz magnetic field exposure have any effects on the circadian rhythm generated in SCN itself.
Wister rats were employed in the experiments. The coil system for magnetic field exposure, three sets of four-square Merritt coils combined perpendicularly one another, was placed in a magnetically and electromagnetically shielded room. A glass-coated bipolar metal microelectrode was inserted stereotaxically into the SCN of a rat anesthetized with Urethane in order to measure the extracellular activity of SCN, and the rat was put into the shielded room and its head was fixed horizontally at the center of the coil system. The rat was kept in the dark and silent condition throughout the experiment. Rats were divided into four groups, one control and three experimentalgroups. The control rats were exposed with 40 muT static magnetic field directing downward during the experiments. The experimental rats were exposed with 50Hz, peak-to-peak of 40 muT, sinusoidal magnetic field along the vertical axis (z-axis), parallel to the longitudinal axis of the head (x-axis) or perpendicular to x-axis in horizontal plane (y-axis) respectively added to the downward static magnetic field. The extracellular activity of SCN was recorded for more than 60 hours.
Clear circadian rhythm appeared in the SCN activity of the control rat. The SCN activity of the rat exposed with the 50Hz magnetic field along z-axis showed circadian rhythm similar way to the control, whereas the remarkable disorder of the circadian rhythm of SCN activity was observed when the rat was exposed with the 50 Hz magnetic field along x-axis or y-axis.
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