Differential sensitivity of the SWV and C57BL/6 mouse strains to the teratogenic action of single administrations of cadmium given throughout the period of anterior neuropore closure

When administered to mice during gestation, the heavy metal, cadmium, is kn own to induce malformations of the neural tube, craniofacial region, limbs, trunk, viscera, and axial skeleton that vary in scope and severity among i nbred strains of mice. Two strains, C57BL/6 and SWV, were previously shown to differ in their susceptibility to exencephaly induced by many teratogeni c treatments, including sodium 2-ethylhexanoate, hyperthermia, valproic aci d, and carbon dioxide, with the SWV strain being consistently more sensitiv e than the C57BL/6 strain. These findings support the observation of Finnel l et al. ([1988] Teratology 38:313-320) of shared hierarchies of relative s usceptibility to exencephaly induced by biochemically distinct teratogens, and suggest that the SWV strain would also be more sensitive to exencephaly induced by cadmium. In the present study, pregnant mice from the two strai ns were exposed to single i.p. injections of cadmium chloride at 4 mg/kg-BW on day 6.5, 7.0, 7.5, 8.0, 8.5, or 9.0 of gestation. Fetuses were removed by cesarean section on day 18 of gestation and scored for malformations. Th e C57BL/6 strain was observed to be more sensitive than the SWV strain to t he induction of exencephaly by cadmium on days 6.5, 7.0, and 8.0, with mean litter percentages of 3.6%, 88.3%, and 62.2%, respectively, compared to 0. 0%, 4.1%, and 27.7% for the SWV strain. This finding provides evidence in c ontrast to the hypothesis of shared hierarchies of sensitivity to teratogen -induced exencephaly. Data on a number of other cadmium-induced malformatio ns are also presented. (C) 1999 Wiley-Liss, Inc.