Evaluation of the potential promoting effect of 60 Hz magnetic fields on N-ethyl-N-nitrosourea induced neurogenic tumors in female F344 rats.
Evaluation of the potential promoting effect of 60 Hz magnetic fields on N-ethyl-N-nitrosourea induced neurogenic tumors in female F344 rats.
复制标题
评估 60 Hz 磁场对 N-乙基-N-亚硝基脲诱导的雌性 F344 大鼠神经源性肿瘤的潜在促进作用。
作者：
Rosemonde Mandeville;Eduardo L. Franco;S. Sidrac;Louise Paris‐Nadon;Normand Rocheleau;G. Mercier;M. Désy;Céline Devaux;L. Gaboury
本研究调查了 60 Hz 磁场 (MF) 作为化学致癌物 N-乙基-N-亚硝基脲 (ENU) 经胎盘引发的神经源性肿瘤促进剂的可能影响。在一项初步研究中，经过 420 天的观察，5 毫克 ENU 可以在 F344 大鼠后代中诱发 30% 至 40% 的神经源性肿瘤。在本研究中，400 只雌性大鼠被分为 8 个不同组（50 只动物/组），并在子宫内（妊娠第 18 天）暴露于单次静脉注射盐水（第 I 组）或 ENU，5 mg/kg（第 II 组至第 VIII 组）。第 II 组的母鼠不接受进一步处理，而第 III 组至第 VII 组的母鼠在 48 小时后暴露于 5 种不同强度的 MF。 III组中的动物进行假暴露（<0.02 microT），而IV至VII组分别暴露于2、20、200和2000 microT。第VIII组的母鼠从第19天到分娩腹腔注射12-O-十四烷酰佛罗醇-13-乙酸酯（TPA；10微克/千克），然后它们的雌性后代继续每15天注射一次，从出生后第14天开始直到处死（阳性对照）。因此，本研究包括三种不同类型的对照：内部对照（第二组和第三组）和阳性对照（第八组）。在生活中暴露期间，对所有动物组的体重、死亡率和临床观察结果进行了评估。对所有在研究结束时死亡、被发现垂死或处死的暴露动物和对照动物进行尸检。对所有脑、脊髓、脑神经、主要器官（肺、肝、脾、肾、垂体、甲状腺和肾上腺）以及尸检期间观察到的所有肉眼病变进行组织病理学评估。所有临床观察和病理评估均在“盲法”条件下进行。这项 ENU/MF 促进研究的结果清楚地表明，在我们定义的实验条件下，暴露于 60 Hz 线性（单轴）正弦连续波 MF 对雌性 F344 大鼠的存活或患有神经源性肿瘤的动物数量没有影响。这些结果表明，MF 对经胎盘暴露于 ENU 的雌性 F344 大鼠的神经源性肿瘤没有促进作用。
The present study investigated the possible effect of 60 Hz magnetic fields (MFs) as promoters of neurogenic tumors initiated transplacentally by a chemical carcinogen, N-ethyl-N-nitrosourea (ENU). In a preliminary study, 5 mg of ENU was shown to induce 30 to 40% neurogenic tumors in F344 rats offspring after 420 days of observation. In the present study, 400 female rats were divided into eight different groups (50 animals/group) and exposed in utero (on day 18 of gestation) to a single intravenous dose of either Saline (Group I), or ENU, 5 mg/kg (Group II to VIII). Dams in group II were given no further treatment while dams in Groups III to VII were exposed to 5 different intensities of MFs forty eight hours later. Animals in group III were sham exposed (<0.02 microT) while groups IV to VII were exposed to 2, 20, 200, and 2000 microT, respectively. Dams in Group VIII were injected intraperitoneally with 12-O-tetradecanoylphrobol-13-acetate (TPA; 10 micrograms/kg) from day 19 until delivery, and then their female offspring continued to be injected every 15 days, starting at day 14 after birth until sacrifice (positive controls). Accordingly, this study included three different types of controls: Internal controls (Groups II and III) and positive control (Group VIII). Body weight, mortality and clinical observations were evaluated in all groups of animals during in-life exposure. Necropsy was performed on all exposed and control animals that died, were found moribund or sacrificed at termination of the study. Histopathological evaluation was done for all brains, spinal cords, cranial nerves, major organs (lungs, liver, spleen, kidneys, pituitary, thyroid and adrenals) and all gross lesions observed during necropsy. All clinical observations and pathological evaluations were conducted under "blinded" conditions. The findings from this ENU/MFs promotion study clearly demonstrate that, under our defined experimental conditions, exposure to 60 Hz linear (single axis) sinusoidal, continuous wave MFs had no effect on the survival of female F344 rats or on the number of animals bearing neurogenic tumors. These results suggest that MFs have no promoting effect on neurogenic tumors in the female F344 rats exposed transplacentally to ENU.