Rat embryos cultured under copper‐deficient conditions develop abnormally and are characterized by an impaired oxidant defense system

Abstract

Rat embryos (gestation days 9.0 and 10.0) obtained from dams that were fed a Cu-adequate (8 micrograms Cu/g) or Cu-deficient (< 0.5 micrograms Cu/g diet were cultured for 48 hr in Cu-adequate (16.2 microM) or Cu-deficient (1.0 microM) rat serum. Control embryos cultured in control serum were morphologically normal. Embryos from Cu-deficient dams developed abnormally when cultured in Cu-deficient serum; the abnormalities included distended hindbrains, blisters, blood pooling, and cardiac defects. Control embryos cultured in Cu-deficient serum and Cu-deficient embryos cultured in control serum also showed abnormal development, but to a lesser degree than that of the Cu-deficient embryos cultured in Cu-deficient serum. To test the idea that the above abnormalities were due in part to free radical induced damage occurring secondary to an impaired oxidant defense system, a chemiluminescence assay was used to detect superoxide dismutase (SOD) activity in the cultured embryos. SOD activity was lowest in embryos cultured in Cu-deficient serum. When the Cu-deficient serum was supplemented with antioxidants (CuZnSOD or glutathione peroxidase), its teratogenicity was reduced. These data support the idea that an impaired oxidant defense system contributes to the dysmorphology associated with Cu deficiency. However, the Cu-deficient embryos also had low cytochrome c oxidase activity compared to control embryos--thus, multiple factors are likely contributing to Cu deficiency-induced abnormalities.

Mutagenicity, Carcinogenicity, and Teratogenicity

“…Zinc, in addition, can protect the embryo from damage caused by other teratogenic agents, though zinc deficiency in the mother may be harmful to the embryo (Jankowski et al 1995). In an experimental rat embryo culture system, abnormal development could also be induced under copper-deficient conditions which were associated with an impaired oxidant defense system (Hawk et al 1998). Information on the teratogenic effects of vanadium have mainly been obtained from various animal test systems, "but vanadium appears to be only slightly teratogenic, if at all" Gerber 1994, Domingo 1996).…”

Copper-Deficient Rat Embryos Are Characterized by Low Superoxide Dismutase Activity and Elevated Superoxide Anions1

“…However, in both the in vivo and in vitro experiments, Cu-deficient embryos were smaller than controls as assessed by head and crown-rump lengths. Consistent with our previous report [4], the control embryos in vivo taken on GD 12 were morphologically similar to the in vitro controls. We observed a small number of abnormalities in the in vivo Cu-FIG.…”

“…The difference in the developmental outcome of the Cu-deficient embryos from the in vivo and in vitro studies may be caused by the teratogenic nature of culture sera, which was more severely depleted in Cu (0.9 M) than in the sera to which the embryos were exposed in utero (ഠ5.0 M). We have shown that when Cu-deficient embryos are cultured in Cudeficient culture media that has been repleted with Cu or are cultured in serum from Cu-adequate animals, the embryonic malformations are decreased [4,31]. These data demonstrate the sensitivity of postimplantation rat embryos to changes in culture Cu concentrations.…”

“…Using an in vitro rat embryo culture model, we have shown that Cu deficiency-induced embryonic anomalies result, in part, from an impaired oxidant defense system [4]. Morphologically, the Cu-deficient embryos were characterized by blisters, blood pooling, heart anomalies, and swollen hindbrain.…”

“…The enzyme SOD catalyzes the dismutation of superoxide anions into less reactive hydrogen peroxides. Under conditions of compromised Cu status, the activities of extracellular and cytosolic CuZnSOD were decreased in developing embryos and in weanling or adult rats [4,[7][8][9]. Lynch et al [10] examined the effects of dietary Cu restriction on oxidative stress and damage in weanling male rats, and they observed a 68% reduction in CuZnSOD activity, a 58% increase in superoxide anions, and an increase in lipid peroxidation.…”