Toxicology 212 (2005) 219–226 The brain is a target organ after acute exposure to depleted uranium P. Lestaevel a,∗ , P. Houpert a , C. Bussy a , B. Dhieux a , P. Gourmelon b , F. Paquet a a Institut de Radioprotection et de Sˆ uret´ e Nucl´ eaire, D´ epartement de Radio-Protection de l’Homme, Laboratoire de Radio-Toxicologie Exp´ erimentale, BP 166, 26702 Pierrelatte, France b Institut de Radioprotection et de Sˆ uret´ e Nucl´ eaire, D´ epartement de Radio-Protection de l’Homme, BP 6, 92265 Fontenay aux Roses, France Received 11 March 2005; received in revised form 29 April 2005; accepted 6 May 2005 Available online 13 June 2005 Abstract The health effects of depleted uranium (DU) are mainly caused by its chemical toxicity. Although the kidneys are the main target organs for uranium toxicity, uranium can also reach the brain. In this paper, the central effects of acute exposure to DU were studied in relation to health parameters and the sleep–wake cycle of adult rats. Animals were injected intraperitoneally with 144 ± 10 g DU kg -1 as nitrate. Three days after injection, the amounts of uranium in the kidneys represented 2.6 g of DU g -1 of tissue, considered as a sub-nephrotoxic dosage. The central effect of uranium could be seen through a decrease in food intake as early as the first day after exposure and shorter paradoxical sleep 3 days after acute DU exposure (-18% of controls). With a lower dosage of DU (70 ± 8 g DU kg -1 ), no significant effect was observed on the sleep–wake cycle. The present study intends to illustrate the fact that the brain is a target organ, as are the kidneys, after acute exposure to a moderate dosage of DU. The mechanisms by which uranium causes these early neurophysiological perturbations shall be discussed. © 2005 Elsevier Ireland Ltd. All rights reserved. Keywords: Depleted uranium; Brain; Paradoxical sleep; Target organ; Kidneys; Toxicity 1. Introduction Uranium (U) occurs naturally in the earth’s crust. It is both a chemical and a radiological toxic element belonging to the actinides group. Depleted uranium (DU) is only slightly radioactive and its toxicity is essentially chemical, like most heavy metals, such as ∗ Corresponding author. Tel.: +33 475 50 74 32; fax: +33 475 50 43 26. E-mail address: philippe.lestaevel@irsn.fr (P. Lestaevel). cadmium, mercury or lead (Priest, 2001; McClain, 2002). The increasing role of U in industrial and military processes has resulted in an increasing occupational exposure to this element. Uranium, after absorption in the gastrointestinal tract or lungs before translocation into the blood, deposits rapidly in the skeleton and kidneys (Priest, 2001). The kidneys are particularly sensitive to the chemotoxic effects of U and are the main target organ with bone (La Touche et al., 1987). 0300-483X/$ – see front matter © 2005 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.tox.2005.05.002