Barone A, Ebesh O, Harper R G, Wapnir R A
Departments of Pediatrics, Obstetrics & Gynecology, North Shore University Hospital-New York University School of Medicine, Manhasset, NY 11030, USA.
J Nutr. 1998 Jun;128(6):1037-41. doi: 10.1093/jn/128.6.1037.
We hypothesized that the competition between zinc (Zn) and copper (Cu) during fetal accretion of copper could be discriminated at either the dam-to-placenta or placenta-to-fetus stage. This premise was tested by feeding dams a high Zn diet (1000 mg/kg, HZn) during the second half of gestation. One day before delivery, dams were anesthetized, fetuses removed and both maternal and fetal tissues and plasma obtained and assayed. Other rats were fed a normal Zn concentration diet (32.4 mg/kg, ND) throughout pregnancy. There were significantly lower fetal liver Cu concentrations and greater plasma Fe concentrations, but not plasma Cu concentrations or liver Fe concentrations in the HZn group. Both dam and fetal Zn liver concentrations were greater in the HZn than in the ND group. Plasma Cu levels were lower in the HZn-fed than in the ND-fed dams. Placental tissue from the HZn litters had a greater concentration of Zn and Fe than did the ND group, whereas no effect was noted for Cu concentration. Metallothionein (MT) levels were elevated in dam livers and placenta in the HZn group, but there were no differences in fetal liver MT. The dynamic assessment of placental transport was conducted by injecting 2.5 mg/kg Cu acetate intravenously into dams of both groups. Sequential samplings of dam and fetal blood and placentas were taken from 0 to 60 min. After the Cu bolus, there was a consistently higher plasma Cu concentration in the HZn than in the ND dams, but no alteration in the concentration of Cu in the placenta or fetal plasma. This study indicates that placental Cu uptake is not affected by a high Zn diet in the dam. In addition, the greater Zn concentration in the placenta of HZn than in ND litters results in abnormal fetal Cu, Fe and Zn concentrations, suggesting that an imbalanced maternal mineral consumption is deleterious to normal divalent metal accretion.
我们推测，在胎儿期铜蓄积过程中，锌（Zn）与铜（Cu）之间的竞争可能在母鼠至胎盘或胎盘至胎儿阶段得以区分。通过在妊娠后半期给母鼠喂食高锌饮食（1000毫克/千克，HZn）来验证这一假设。分娩前一天，对母鼠实施麻醉，取出胎儿，并获取母鼠和胎儿的组织及血浆进行检测。其他大鼠在整个孕期喂食正常锌浓度饮食（32.4毫克/千克，ND）。HZn组胎儿肝脏铜浓度显著降低，血浆铁浓度升高，但血浆铜浓度和肝脏铁浓度未受影响。HZn组母鼠和胎儿肝脏锌浓度均高于ND组。喂食HZn的母鼠血浆铜水平低于喂食ND的母鼠。HZn窝仔的胎盘组织中锌和铁的浓度高于ND组，而铜浓度未受影响。HZn组母鼠肝脏和胎盘中金属硫蛋白（MT）水平升高，但胎儿肝脏MT无差异。通过给两组母鼠静脉注射2.5毫克/千克醋酸铜来动态评估胎盘转运。在0至60分钟内对母鼠和胎儿的血液及胎盘进行连续采样。注射铜后，HZn组母鼠血浆铜浓度始终高于ND组，但胎盘或胎儿血浆中铜浓度未发生改变。本研究表明，母鼠高锌饮食不影响胎盘对铜的摄取。此外，HZn窝仔胎盘锌浓度高于ND窝仔，导致胎儿铜、铁和锌浓度异常，表明母体矿物质摄入不均衡对正常二价金属蓄积有害。
