Enriched but not depleted uranium affects central nervous system in long-term exposed rat

Uranium is well known to induce chemical toxicity in kidneys, but several other target organs, such as central nervous system, could be also affected. Thus in the present study, the effects on sleep-wake cycle and behavior were studied after chronic oral exposure to enriched or depleted uranium. Rats exposed to 4% enriched uranium for 1.5 months through drinking water, accumulated twice as much uranium in some key areas such as the hippocampus, hypothalamus and adrenals than did control rats. This accumulation was correlated with an increase of about 38% of the amount of paradoxical sleep, a reduction of their spatial working memory capacities and an increase in their anxiety. Exposure to depleted uranium for 1.5 months did not induce these effects, suggesting that the radiological activity induces the primary events of these effects of uranium. © 2005 Elsevier Inc. All rights reserved

Heterogeneous accumulation of uranium in the brain of rats

Recent reports suggest that uranium can accumulate not only in known target organs, that is, kidneys or bones, but also in others such as central nervous system. In the present work, the accumulation of uranium in the brain of rats was studied after repeated exposure by inhalation, chronic exposure by ingestion and acute exposure by injection. For each route of administration, the amount of uranium entering the brain was low. The results showed different accumulation in the brain areas according to the route of intake. Injection gave a rather homogeneous distribution in the different brain areas, whereas both inhalation and ingestion yielded heterogeneous but specific accumulation. These differences in distribution suggest the operation of different mechanisms of delivery of uranium to the brain tissues. © The Author 2007. Published by Oxford University Press. All rights reserved

Changes in sleep-wake cycle after chronic exposure to uranium in rats

International audienceUranium is a heavy metal known to induce toxicity in kidneys. It is also known to enter the central nervous system, thus inducing neurophysiological effects, after exposure to relatively high concentrations. The effect of chronic uranium exposure (40 mg l(-1) in drinking water, for 90 days) on electroencephalographic architecture has been studied on freely moving rats using a telemetry technique. The main effects of uranium on the sleep-wake cycle were an increase in rapid eye movement sleep (REM-sleep) and theta band power during the light period, as early as Day 30 after exposure commenced. The most probable explanation for these effects is that uranium directly affects the brain. This increase in REM-sleep was previously described in human depression or models of chronically stressed rats and it may be assimilated with some protective or compensatory mechanisms