Behavioural and neurotoxicological changes caused by cadmium treatment of rats during development

Behavioural and electrophysiological changes caused by inorganic cadmium were investigated in the offspring of female Wistar rats. Dams were given 3.5, 7.0 or 14.0 mg kg(-1) cadmium (cadmium chloride dissolved in distilled water) in three different treatment regimes: days 5-15 of pregnancy; days 5-15 of pregnancy + 4 weeks of lactation; days 5-15 of pregnancy + 4 weeks of lactation followed by the same oral treatment of male rats of the F1 generation for 8 weeks. The behavioural (open-field exploration) and electrophysiological (electrocorticogram, cortical evoked potentials, conduction velocity and refractory periods of a peripheral nerve) parameters of F1 male rats exposed by various treatments were investigated at the age of 12 weeks. It was found that cadmium dose and treatment time dependently altered the spontaneous and evoked electrophysiological functions (e.g. increased the frequency of the electrocorticogram, lengthened the latency and duration of evoked potentials, etc.). Interestingly, only the combination of treatment during prenatal development and the 4-week suckling period resulted in a significant dose-dependent decrease of horizontal and vertical exploratory activity and a significantly lower exploration frequency of the open-field centre. The results showed that low-level pre- and postnatal inorganic cadmium exposure affects the bioelectrical and higher order functions of the nervous system. In the case of human populations, a similar prolonged exposure might be just as harmful.