Zinc Supplementation During Pregnancy Alleviates Cadmium-induced Developmental Toxicity In Mice

Objective Numerous data showed that trimester maternal exposure to cadmium resultedin intrauterine growth retardation, malformations and intrauterine death. Zinc is one ofthe essential trace elements in fetal growth. The present study was to investigate theprotective effects of zinc supplementation during pregnancy on cadmium-induceddevelopmental toxicity in mice, and its mechanisms.Methods All pregnant mice were randomly divided into four groups. In cadmiumtreatment and zinc plus cadmium groups, pregnant mice received an intraperitonealinjection of CdCl2(4.5mg/kg) on gestational day (GD)9. In Zinc treatment and zincplus cadmium groups, mice were exposed to zinc sulfate (186mg/L dissolved indrinking water) from GD1to GD18. On GD18, all pregnant mice were killed. Thenumbers of live fetuses, dead fetuses and resorptions were counted. Live fetuses in eachlitter were weighed, measured for crown-rump lengths, examined for external defectsand skeletal development, and detected for GSH content in placenta and fetal liver,cadmium and zinc content in placenta, fetal plasma and fetal liver.Results As compared with the controls, the numbers of dead fetuses per litter andmalformed fetuses per litter were significantly increased in cadmium group. Fetalweight and crown-rump length were obviously decreased in cadmium-treated mice.Skeletal development of the sternum, the heel (toe) and the coccyx bone were markedlyinhibited in cadmium-treated fetuses. Zinc supplementation during pregnancysignificantly protected against cadmium-induced fetal death and external malformations,attenuated cadmium-evoked fetal growth retardation and skeletal dysplasia. Furtherstudy found that maternal cadmium exposure during pregnancy significantly reducedGSH content in placental and fetal liver of mouse, whereas zinc supplementation duringpregnancy significantly improved the decrease in the placenta GSH content induced by cadmium. Additional results showed maternal cadmium treatment during pregnancyobviously increased the content of cadmium in mouse placenta but fetal plasma andliver. Zinc supplementation during pregnancy had no effect on cadmium accumulationin mouse placenta. Zinc analysis showed maternal cadmium treatment during pregnancydid not cause the change of the zinc content in the mouse placenta, fetal plasma andliver, and zinc supplementation did not affect the zinc content in the mouse placenta,fetal plasma and liver.Conclusion Zinc supplementation during pregnancy significantly alleviatescadmium-induced developmental toxicity via inhibitting.cadmium-evoked oxidativestress in mouse placenta.