Toxicology A study of dose response and organ susceptibility of copper toxicity in a rat model Vijay Kumar a , Jayantee Kalita a, *, U.K. Misra a , H.K. Bora b a Department of Neurology, Sanjay Gandhi Post Graduate Medical Sciences, Raebareily Road, Lucknow 226014, India b Laboratory Animal Division, Central Drug Research Institute, Lucknow, India A R T I C L E I N F O Article history: Received 4 April 2014 Received in revised form 3 June 2014 Accepted 5 June 2014 Keywords: Copper Liver Kidney Brain Toxicity A B S T R A C T Copper (Cu) in higher concentration is toxic and results in various organ dysfunction. We report Cu concentration in liver, brain and kidney in the rat model following chronic exposure of oral copper sulphate at different subtoxic doses and correlate the tissue Cu concentrations with respective organ dysfunction. Fifty-four male wistar rats divided in 3 groups, the control group received saline water and the experimental group (Group-IIA and IIB) received oral copper sulphate in dose of 100 and 200 mg/kg Body Weight. At the end of 30 days, 60 days and 90 days of exposure, six rats were sacrificed from each group. The maximum peak force in grip strength, latency to fall in rotarod and percentage attention score in Y-maze were significantly reduced in the copper sulphate exposed rats compared to the controls at all time points and these were more marked in Group-IIB compared to Group-IIA. Cu concentration was significantly higher in liver, kidney and brain in the Group-II compared to the Group-I. The Cu concentration was highest in the liver (29 folds) followed by kidney (3 folds) and brain (1.5 folds). Serum ALT, AST and bilirubin correlated with liver Cu, BUN with kidney Cu, and grip strength, rotarod and Y- maze findings correlated with brain Cu level. In rats, chronic oral copper sulphate exposure at subtoxic level results in neurobehavioral abnormality and liver and kidney dysfunctions due to increased Cu concentration in the respective organs. Liver is the most vulnerable organ and copper toxicity increases with increasing dose and duration of exposure. ã 2014 Elsevier GmbH. All rights reserved. 1. Introduction Copper (Cu) is an essential trace metal that plays an important role in many biological functions and serves as a cofactor for several enzymes. Cu uptake, distribution within the cells, detoxification and removal are maintained by an elegant system. Mutations in genes involved in Cu homeostasis are responsible for disorders of Cu metabolism in humans. The best described human Cu toxicosis disorder is Wilson disease (WD) which is an autosomal recessive disease due to ATP7B gene mutation which leads to defective Cu transportation and excretion into the bile [1]. The main pathogenesis of cellular injury in WD is due to the presence of excess free Cu which results in cirrhosis of the liver, Kayser Fleischer ring, renal tubular dysfunction and brain damage [2]. Clinically, the WD patients have liver dysfunction in the first decade and neurological dysfunction in the second decade [3]. Many WD patients with neurological manifestation may not have a history of hepatic dysfunction. Central nervous system (CNS) is privileged as it is protected from most of the toxic agents and infections because of blood brain and blood cerebrospinal barriers. However, free Cu is capable of crossing blood brain barrier resulting in oxidative stress mediated cell damage [4,5]. On cranial MRI, certain areas of the brain such as corpus striatum, thalamus and substantia nigra are more frequently involved in WD suggesting vulnerability of these areas to Cu toxicity [6–8]. Recently Long Evans Cinnamon (LEC) rat and toxic milk mice have been developed to replicate the WD and to evaluate the various aspect of Cu induced toxicity [9–11]. The well-established model for WD, LEC rat has a deletion in the ATP7B gene leading to a non-functioning protein. The animals steadily accumulate Cu in the liver and develop hepatic manifestation at the age of about 3 months [11]. LEC rat has symptoms similar to hepatic manifesta- tion but does not exhibit symptoms similar to neurological Abbreviations: ALT, alanine aminotransferase; AST, aspartate aminotransferase; BUN, blood urea nitrogen; CNS, central nervous system; Cu, Copper; kgBWt, kg Body Weight; LEC, Long Evans Cinnamon; MRI, magnetic resonance imaging; WD, Wilson disease. * Corresponding author. Tel.: +91 522 2494169; fax: +91 0522 2668811. E-mail addresses: jayanteek@yahoo.com, jkalita@sgpgi.ac.in (J. Kalita). http://dx.doi.org/10.1016/j.jtemb.2014.06.004 0946-672X/ ã 2014 Elsevier GmbH. All rights reserved. Journal of Trace Elements in Medicine and Biology 29 (2015) 269–274 Contents lists available at ScienceDirect Journal of Trace Elements in Medicine and Biology journal homepa ge: www.elsevier.de/jtemb