[Effects of millimeter wave irradiation with different frequency and power density on their offsprings in mice].
OBJECTIVE
To determine the threshold of millimeter wave irradiation leading to fetal damage in mice and to clarify the mechanism of decrease in their learning and memory function.


METHODS
Pregnant mice were irradiated by millimeter wave with frequencies of 37.4, 42.2, 53.0 and 60.0 GHz at power densities of 1 to 8 mW/cm2 for two hours daily from the 6th to 15th day of their gestation. Learning and memory functions of their offsprings were tested by a Y-type electric maze. M-cholinergic receptor (M-R), monoamine transmitter and arginine vasopressor (AVP) in the brain were determined for their offsprings by receptor radiation binding analysis (RBA), high performance liquid chromatography-electrochemical detection (HPLC-ECD) and radioimmunoassay (RIA).


RESULTS
The minimal power density of millimeter wave of 37.4, 42.2, and 53.0, 60.0 GHz causing the decrease in learning and memory function, increase of Bmax in the hippocampus and decrease in dopamine (DA) in the brain of the adult offspring mice was five and three mW/cm2 and that causing the decrease in AVP in the hypothalamus was eight and five mW/cm2. Severity of damage in fetal offspring mice caused by irradiation increased with the power density of millimeter wave. Millimeter wave could not cause the increase of their body temperature in pregnant mice.


CONCLUSIONS
Threshold of millimeter wave with frequencies of 37.4, 42.2 and 53.0, 60.0 GHz causing fetal damage in mice was three to five mW/cm2 and one to three mW/cm2, respectively. The decrease in learning and memory functions in offspring mice related with lowering of AVP and DA in the brain and of activity in cholinergic nerve. All these were caused by the non-thermal effects of millimeter wave without a frequency-specific pattern.
D000818:Animals; D005260:Female; D018782:Maze Learning / Q000528:radiation effects; D008568:Memory / Q000528:radiation effects*; D051379:Mice; D008807:Mice, Inbred BALB C; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D011846:Radio Waves / Q000009:adverse effects*