Effect of dietary cadmium and/or lead on histopathological changes in the kidneys and liver of bank voles Myodes glareolus kept in different group densities

Aneta Salińska,Tadeusz Włostowski,Elżbieta Zambrzycka

doi:10.1007/s10646-012-0979-z

Abstract

Bank voles free living in a contaminated environment are known to be more sensitive to cadmium (Cd) toxicity than the rodents exposed to Cd under laboratory conditions, but the reasons for this difference are poorly defined. The present work was designed to determine whether dietary lead (Pb), a common environmental co-contaminant, and/or animal density that affects various physiological processes, would influence susceptibility to Cd toxicity in the kidneys and liver of these animals. For 6 weeks, the female bank voles were kept individually or in a group of six and provided with diet containing environmentally relevant concentrations of Cd [<0.1 μg/g (control) and 60 μg/g dry wt] and Pb [<0.2 μg/g (control) and 300 μg/g dry wt] alone or in combination. At the end of exposure period, histopathology and analyses of metallothionein, glutathione and zinc that are linked to a protective effect against Cd toxicity, as well as Cd, Pb, copper, iron and lipid peroxidation were carried out. Histopathological changes in the kidneys (a focal glomerular swelling and proximal tubule degeneration) and liver (a focal hepatocyte swelling, vacuolation and inflammation) occurred exclusively in some bank voles kept in a group and exposed to Cd alone (2/6) or Cd + Pb (4/6). The observed toxicity in grouped bank voles appeared not to be based on altered (1) tissue disposition of Cd and/or Pb, (2) metallothionein, glutathione and zinc concentrations, or (3) tissue copper, iron and lipid peroxidation. The data indicate that high population density in combination with environmental Pb may be responsible for an increased susceptibility to Cd toxicity observed in bank voles free living in a contaminated environment; the mechanism by which animal density affects Cd toxicity deserves further study.

Highlights

Cadmium (Cd) and lead (Pb) are important toxic metals occurring in the environment naturally and as pollutants emanating mainly from industrial sources (Liu 2003; Satarug et al 2003; Thevenod 2009)
Similar histopathological changes typical for Cd toxicity have been found in the kidneys of small mammals such as yellow-necked mice Apodemus flavicolis, bank voles, wood mice Apodemus sylvaticus and white-toothed shrews Crocidura russula free living in an area polluted with heavy metals (DamekPoprawa and Sawicka-Kapusta 2003, 2004; SanchezChardi et al 2009)
Subchronic consumption of dietary Cd and Pb alone or in combination had no effect on body weight (Table 1) and food intake (0.15–0.18 g/g body wt/day) in the bank voles kept individually (LD voles) or in a group of six (HD voles)

Summary

Introduction

Cadmium (Cd) and lead (Pb) are important toxic metals occurring in the environment naturally and as pollutants emanating mainly from industrial sources (Liu 2003; Satarug et al 2003; Thevenod 2009). Similar histopathological changes typical for Cd toxicity have been found in the kidneys of small mammals such as yellow-necked mice Apodemus flavicolis, bank voles, wood mice Apodemus sylvaticus and white-toothed shrews Crocidura russula free living in an area polluted with heavy metals (DamekPoprawa and Sawicka-Kapusta 2003, 2004; SanchezChardi et al 2009). In small mammals inhabiting an industrialized area accumulation of Cd and appreciable concentrations of Pb in the kidneys have been detected (Damek-Poprawa and Sawicka-Kapusta 2003, 2004) It is known from animal studies that chronic exposure to Pb can lead to nephropathy, including nephromegaly and dysfunction of proximal tubules (Liu et al 2012; Qu et al 2002). MT, GSH and Zn are linked to a protective effect against Cd toxicity (Chan and Cherian 1992; Jacquillet et al 2006; Jihen et al 2008; Klaassen et al 2009; Tang et al 1998), while Cu, Fe and oxidative stress are considered to be responsible for the progression of toxicity (Liu et al 2009; Thevenod and Friedmann 1999; Whittaker et al 2011)

Materials and methods

Results

Discussion