Toxicity of depleted uranium on isolated liver mitochondria: a revised mechanistic vision for justification of clinical complication of depleted uranium (DU) on liver

Abstract

Depleted uranium (DU) is widely used in military anti-armor weapons. Recent evidence suggested that oxidative stress and mitochondrial dysfunction may contribute to DU-induced toxicity. However, the underlying mechanisms of DU toxicity in mitochondria are not well understood. In this study, liver mitochondria were obtained from Wistar rats treated with DU in the form of uranyl acetate (UA) (0.5, 1 or 2 mg/kg i.p.) using differential centrifugation. For in vitro experiments, control rat liver mitochondria were incubated with different concentrations of UA (50, 100 or 200 μM) for 1 hr. Mitochondrial reactive oxygen species (ROS) production, collapse of mitochondrial membrane potential, and mitochondrial swelling were examined by flow cytometry. Mitochondrial sources of ROS formation were determined using specific substrates and inhibitors. Extent of lipid peroxidation (LPO) and glutathione (GSH) oxidation, and also complex II and IV activities were detected via spectroscopy. Further, the concentration of ATP and ATP/ADP ratio was measured using luciferase enzyme and release of cytochrome c from mitochondria which was detected by ELISA kit. UA induced succinate-supported mitochondrial ROS production, elevated LPO levels, GSH oxidation, and mitochondrial complex II inhibition. UA also induced mitochondrial permeability transition and increase in cytochrome c release which subsequently disturbed oxidative phosphorylation and reduced the mitochondrial ATP concentration. Data suggest that mitochondrial oxidative stress and uncoupling of oxidative phosphorylation may play key roles in DU-induced hepatic toxicity.

Keywords:

• depleted uranium
• isolated liver mitochondria
• toxicity
• oxidative stress
• electron transfer chain
• oxidative phosphorylation

Acknowledgments

The data provided in this article were extracted from the PhD thesis of Dr Fatemeh Shaki. The thesis was conducted under the supervision of Prof. Jalal Pourahmad at the Department of Toxicology and Pharmacology, Faculty of Pharmacy, Shahid Beheshti University of Medical Sciences, Tehran, Iran. This study was supported by a grant from Shahid Beheshti University of Medical Sciences (88/01/94/6534, 2009).