報告書番号

U01048

タイトル（和文）

実験小動物における50Hz商用周波磁界の雄性生殖機能、メラトニン分泌への影響

タイトル（英文）

Studies of 50 Hz magnetic fields on male reproductive function and the concentration of serum melatonin in small laboratory animals.

概要 （図表や脚注は「報告書全文」に掲載しております）

雄の生殖機能、メラトニン分泌への商用周波磁界曝露の影響を明らかにするため、ｺﾞｰﾙﾃﾞﾝ(ｼﾘｱﾝ)ﾊﾑｽﾀｰを用いた実験は短日照明下(8L:16D)で13週齢、26週齢および39週齢から50 Hz、350μTの回転円磁界に４、８、12週間曝露した。また、ラットの実験は10週齢のSD系およびWistar系ラットを用い、通常の飼育照明条件下で350μTの回転円磁界あるいは250μTの水平磁界を３、６、12週間曝露し、血清中テストステロンおよびメラトニン濃度を測定するとともに、生殖器系器官重量を対照群と比較した。また、ハムスタ－の実験では生殖器系器官の組織学的検査、および、精子数などの測定も実施した。その結果、ハムスタ－、ラットの実験とも一部の検査項目で対照群と曝露群との間に有意差がみられる場合があったが、一貫した傾向はみられず、磁界曝露に起因すると考えられる影響は認められなかった。以上の結果から、今回の実験条件下ではハムスタ－およびラットの雄性生殖器系およびこれらの機能に影響すると考えられる血清中メラトニンおよびテストステロン濃度に商用周波磁界は影響を及ぼさないことが明らかになった。

概要 （英文）

The effects of 50 Hz magnetic fields (MF) exposure on male reproductive function and the concentration of serum melatonin were studied utilizing golden hamsters under short photo period (8L:16D) and two strains of rats under normal photo period (12L:12D). Hamsters at 13, 26, or 39 weeks of age were exposed to 50 Hz, 350μT MF for 4, 8 or 12 weeks. Male Sprague-Dawley and Wistar rats of 10 weeks of age were exposed to 50 Hz, 350μT circularly or 250μT horizontal magnetic field for 3, 6 or 12 weeks. After MF exposure, animals were sacrificed at midnight, 5-7 hours from the beginning of dark phase, and the concentrations of melatonin and testosterone in sera were measured. Sexual organs, including testes, were excised and weighed. In addition, histopathological examination of sexual organs was performed and sperm number and the incidence of abnormal sperm were counted in hamster study. In both studies, there found no exposure-related toxicity, including body weight gain. In hamster study, atrophy of sexual organs and decreased concentration of serum testosterone were observed responding to the exposure duration under the short photo period, and these were prominent in older ones. However, these changes were not related to MF exposure. In rat study, there was only one parameter, weight of prostate glands after 3 week exposure to 250μT, horizontally polarized MF, revealing the statistically significant difference compared with that of sham exposed group in Wistar rats. However, the other sexual organ weights and the serum concentration of midnight melatonin and testosterone of MF exposure groups were comparable to correspondent control groups in two strains of rats. Based on these results, we conclude that power frequency, 50 Hz MF does not affect male reproductive function and the concentration of serum melatonin in golden hamster, Sprague-Dawley and Wistar rats.

報告者

キーワード