The developing brain is known to be sensitive to the toxic effects of methylmercury (MeHg). The effects of toxic levels of MeHg exposure during the most seemingly vulnerable window of the cerebrum are not well studied. In this study, we aimed to examine the specific effects of toxic levels of MeHg on neurobehavior, neurodegeneration, and selenoenzyme activity in the cerebrum of infant rats. Male Wistar rats (n = 8/group) were orally treated with MeHg at an acute toxic dose (8 mg Hg/kg/day) for 10 consecutive days starting on postnatal day 14 (P14). The MeHg-exposed rats showed a significant reduction in body weight after day 8 and severe neurological symptoms similar to dystonia on day 12 (P25). Motor coordination deficits determined using the rotarod performance test and short-term memory impairment determined using the Y-maze task were observed in the MeHg-exposed rats on day 11 (P24). The MeHg-exposed rats sacrificed on day 12 showed severe cerebral neuronal degeneration, reactive astrocytosis, and TUNEL-positive apoptotic nuclei, with the cerebral Hg concentration of 15.0 ± 1.6 μg/g. Furthermore, the activities of glutathione peroxidase and thioredoxin reductase in the cerebrum in MeHg-exposed rats were lower than those in control. These results indicate that MeHg exposure to infant rats will be useful to predict the effects of MeHg at the cerebral growth spurt in humans.

已知发育中的大脑对甲基汞（MeHg）的毒性作用敏感。尚未充分研究在看似最脆弱的大脑窗口期间暴露于MeHg的毒性水平的影响。在这项研究中，我们旨在检查MeHg的毒性水平对幼鼠大脑神经行为，神经退行性和硒酶活性的特定影响。从出生后第14天起，连续10天以急性毒性剂量（8 mg Hg / kg /天）口服MeHg雄性Wistar大鼠（n = 8 /组）（P14）。暴露于MeHg的大鼠在第8天后体重显着降低，并且在第12天出现类似于肌张力障碍的严重神经系统症状（P25）。在第11天（P24）在暴露于MeHg的大鼠中观察到了使用轮转性能测试确定的运动协调缺陷和使用Y迷宫任务确定的短期记忆障碍。在第12天处死的暴露于MeHg的大鼠表现出严重的脑神经元变性，反应性星形细胞增多和TUNEL阳性凋亡核，其脑Hg浓度为15.0±1.6μg/ g。此外，暴露于MeHg的大鼠大脑中谷胱甘肽过氧化物酶和硫氧还蛋白还原酶的活性低于对照组。这些结果表明，暴露于幼鼠的MeHg将有助于预测MeHg对人脑生长突增的影响。和TUNEL阳性凋亡细胞核，脑汞浓度为15.0±1.6μg/ g。此外，暴露于MeHg的大鼠大脑中谷胱甘肽过氧化物酶和硫氧还蛋白还原酶的活性低于对照组。这些结果表明，暴露于幼鼠的MeHg将有助于预测MeHg对人脑生长突增的影响。和TUNEL阳性凋亡细胞核，脑汞浓度为15.0±1.6μg/ g。此外，暴露于MeHg的大鼠大脑中谷胱甘肽过氧化物酶和硫氧还蛋白还原酶的活性低于对照组。这些结果表明，暴露于幼鼠的MeHg将有助于预测MeHg对人脑生长突增的影响。