Methylmercury (MeHg) taken up through fish consumption can be transferred from the mother to the fetus during pregnancy. In the present study, pregnant rat mothers were contaminated with environmentally relevant doses of 36 and 76 ng MeHg/g of food using diets containing naturally mercury-containing fish. Young female rats fed with fish-containing food after weaning showed decreased locomotion in Y maze for accumulated concentrations in brain as low as 75 ng Hg/g dry weight (15 ng Hg/g wet weight). Young female rats fed the control diet after weaning yet borne by mothers fed the diet containing 76 ng MeHg/g, presented a 58% reduced activity in the open-field labyrinth, meaning that the maternal exposure to fish-containing food exerted an effect in utero that lasted several weeks after birth. Newborns were protected against Hg exposure by the placental barrier since in newborns from mothers fed the diet containing 76 ng MeHg/g of food, the concentrations of Hg in brain, kidney, liver and skeletal muscles represented 12, 3, 21 and 18% of those of their mother's tissues, respectively. These results suggest the existence, at least in rats, of a threshold level in terms of MeHg exposure above which the placental barrier collapses.

通过食用鱼类吸收的甲基汞（MeHg）在怀孕期间可以从母亲转移到胎儿。在本研究中，使用含有天然含汞鱼的饮食，怀孕的大鼠老鼠的食物受到与环境有关的剂量分别为36和76 ng MeHg / g的食物的污染。断奶后喂食含鱼食物的雌性幼鼠在Y迷宫中的运动减少，因为脑中的累积浓度低至75 ng Hg / g干重（15 ng Hg / g湿重）。断奶后喂食对照饮食的雌性幼鼠，但由母亲喂食含76 ng MeHg / g饮食的雌性大鼠，在开放田间迷宫中的活性降低了58％，这意味着母体暴露于含鱼食物会产生一定的影响。子宫出生后持续了几周。新生儿受到胎盘屏障的保护，因为母亲喂养的饮食中含有76 ng MeHg / g的食物，其脑，肾，肝和骨骼肌中Hg的含量分别占胎盘的12％，3％，21％和18％分别是他们母亲的组织。这些结果表明，至少在大鼠中，存在MeHg暴露阈值水平，超过该阈值胎盘屏障就会崩溃。