[The effect of cadmium on the wakefulness-sleep cycle in rats in early postnatal ontogeny]

The influence of cadmium chloride on behavioural and EEC characteristics of sleep-wakefulness cycle in the newborn Wistar rats (from the 5th to the 14th day of life) was investigated under conditions of the acute and chronic experiment. It is found that single injection of cadmium has caused the increase in wakefulness time. The slow and active sleep stage duration became shorter for three times. The moderate increase in alpha-range wave power for both stages of sleep is a characteristic of EEG for sleep on the background of the acute cadmium injection. The chronic injection of toxic matter is accompanied by appearance of cataleptic state in the sleep-wakefulness cycle. Its intensity increases for 2 weeks with every new injection. The electron-microscopic investigation of nerve fibers of caudate putamen and corpus callosum conducted on animals 2 weeks old (in a week after the last injection) has found the nerve fibers demyelination, increase in share of microtubules compared to neurofilaments. All these features are typical for earlier postnatal period of the brain development (the 4-5th day of life). It is suggested that under the chronic injection in the early ontogenesis cadmium penetrates through hematoencephalic barrier and induces the structural and functional CNS organization delay.