Cadmium and zinc concentrations in fetal and maternal rat tissues after parenteral administration of cadmium during pregnancy

Abstract

Cadmium (Cd) and zinc (Zn) concentrations were determined by solid sampling atomic absorption spectrometry (AAS) in rat maternal and fetal tissues after exposure to cadmium. Cadmium was administered subcutaneously as CdCl2 in saline daily during pregnancy. Two experiments were performed. In expt. I we investigated the tissue concentration at day 19 (gestational age) after administration of several doses: 0, 1.1, 2.2, 4.4, and 8.8 mumol Cd/kg/day. In expt. II the course of the Cd and Zn concentrations during pregnancy was investigated by collecting samples at days 14, 16, 18 and 20, after daily injections of 4.4 mumol Cd/kg. Cadmium concentrations in blood, maternal liver, placenta and fetal liver increased with dose and duration of exposure. Cadmium was heavily accumulated in the liver and transferred to the fetus only in small amounts. The zinc concentration in the maternal liver was positively correlated with the cadmium concentration. In the placenta the zinc concentration was not affected. Zinc in fetal liver was decreased from day 18 onward. Despite relatively high cadmium levels and decreased zinc levels in the fetus, we observed no adverse effects on various reproduction parameters, such as birth weights and obvious malformations.

Effects of Periconception Cadmium and Mercury Co-Administration to Mice on Indices of Chronic Diseases in Male Offspring at Maturity

“…However, in the present studies Cd and Hg administration started 4 days before conception and ceased before the normal day of embryo implantation. While it is possible that the apparent effect on anxiety-like behavior was the consequence of developmental programming rather than a direct impact of Cd and Hg on the organ systems of the developing fetus, it is not possible to rule out direct exposure through placental transfer (Hazelhoff Roelfzema et al 1988; Lau et al 1998) and possibly exposure of nursing pups after birth (Bekheet 2011; Petersson Grawé et al 2004), given the long half-lives of Cd and Hg (Fair et al 1987; Feldman et al 1978; Magos and Butler 1976). …”

“…Available studies for gestational Cd or Hg exposure at varying doses during the entire pregnancy or before parturition suggest accumulation of these heavy metals mainly in maternal tissues and placenta (Barański et al 1982; Lau et al 1998). In contrast, only small amounts of Cd or Hg were detected in fetal organs (Hazelhoff Roelfzema et al 1988; Lau et al 1998). Given long half-lives of Cd and Hg, their exposure would have persisted beyond the periconception time window in dams.…”

Prenatal cadmium exposure produces persistent changes to thymus and spleen cell phenotypic repertoire as well as the acquired immune response

“…In attempting to develop a unifying hypothesis to explain these results it is important to emphasize that Cd only crosses the placenta minimally, if at all, but does accumulate in the placenta (Hazelhoff et al , 1988; Loiacono et al , 1992). Therefore, knowing and understanding how Cd affects any immune cell directly may not be as applicable as its mode of action on the placenta, as an example.…”

“…Known effects of Cd that might influence the fetal metabolism sufficiently to cause this defect include the ability of Cd to displace zinc (Zn) (Martelli et al , 2006). Prenatal Cd administration results in a Zn deficiency in the dam and the fetal liver (Hazelhoff et al , 1988) and this could affect the function of Zn-finger containing transcription factors or other signaling molecules associated with fetal development. An important Zn-dependent developmental molecule is the morphogen sonic hedgehog (Shh) (Day et al , 1999).…”