Study on preventing systems of fetus for uteroplacental circulatory disturbances and uteroplacental dysfunctions produced by microwaves

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We tried to clarify preventing mechanisms including neuroendocrine systems of fetus for uteroplacental circulatory disturbances and uteroplacental dysfunctions produced by microwaves. We simulated the microwave condition in pregnant rats for the specific absorption ratio (SAR) of 0.4 W/kg, which is the maximum permissible exposure level recommended by the American Conference of Industrial Hygienists (ACGIH) and the American National Institute (ANSI). The pretreatment of intravenous (iv) administration of CRH receptor antagonist, α-helical CRH (9-41) as well as a cyclooxygenase inhibitor indomethacin prevented the uteroplacental circulatory disturbances during microwaves. Although microwaves did not induce fetal hypothalamic CRH mRNA change, the administration of bosentan or indomethacin before microwave exposure did it These results suggest a preventing system of uteroplacenta-fetus against microwaves in which fetal hypothalarnic CRH is involved in mediating uteroplacental circulation during microwaves at 0.4 W/kg. By contrast, we found that the preventing systems did not work during microwaves at 2.0 W/kg, subsequently resulting a significant increase in colonic temperature and decrease in uteroplacental blood flow. These results suggest microwaves at the SAR of 0.4 W/kg, which is the maximum permissible exposure level, is within safety levels without producing uteroplacental dysfunctions. Microwaves much above the maximum permissible level may show some harmful changes during pregnancy associated with an increase in colonic temperature produced microwaves.