Low-level cadmium exposure increases one-way avoidance in juvenile rats

Twenty-seven pregnant rats from three genetic lines, Roman High Avoidance (RHA), Roman Low Avoidance (RLA), and Satinder's Heterogeneous Stock (SHS), received daily SC injections of either 0.075 mg/kg CdCl2 (low dose), 0.225 mg/kg CdCl2 (high dose), or an equivalent volume of saline vehicle (control) throughout gestation. Cd-exposed progeny from the RHA genetic line weighed significantly less than RHA control progeny (pd 35-44); however, SHS progeny from the low-dose group weighed significantly more than progeny from any other group (pd 14-44). Unconditioned escape response (UER) level was determined on pd 39. Progeny from the high-dose group required a significantly lower UER level as compared to the low-dose group. Acquisition of conditioned avoidance responses was tested from pd 41 to 44. There were significant differences due to dose for one-way avoidance responses. Cd-related differences in one-way avoidance were restricted to progeny from the SHS genetic line. SHS progeny from the high-dose group demonstrated significantly more one-way responses when compared to the control group. Differences in avoidance responses are discussed in relation to Cd-induced hypernociception. The concentration of Cd in the liver and kidney of dams and progeny was determined by Inductively Coupled Plasma spectroscopy (ICP). There were significant dose-related differences in Cd concentration in maternal tissues.