Cadmium-induced oxidative stress in Prussian carp (Carassius gibelio Bloch) hepatopancreas: ameliorating effect of melatonin

Ewa Drąg-Kozak,Magdalena Socha,Ewa Łuszczek-Trojnar,Katarzyna Gawlik,Włodzimierz Popek,Bogdan Solnica,Grzegorz Gosiewski,Dorota Pawlica-Gosiewska

doi:10.1007/s11356-019-04595-3

Abstract

The oxidative status of the hepatopancreas of Prussian carp females (Carassius gibelio) co-exposed to sublethal cadmium in water and melatonin was studied. The activities of antioxidant enzymes such as glutathione reductase (GR), glutathione peroxidase (GPx), and superoxide dismutase (SOD) as well as the concentration of reduced glutathione (GSH) were measured in homogenates of the hepatopancreas. Furthermore, concentrations of cadmium (Cd), zinc (Zn), copper (Cu), and iron (Fe) in the hepatopancreas were assayed. These females received melatonin implants and were exposed to 0.4 mg/L or 4.0 mg/L Cd in water for either a 13- or a 7-week period, followed by further 6 weeks of purification in clear water. Exposure to Cd influenced the increase in this metal concentration in fish hepatopancreas. In contrast, the fish exposed to cadmium with additional administration of melatonin had a lower accumulation of this metal. Exposure to Cd caused the increase in GSH content and the activity of GR, and a reduction in GPx activity, whereas the SOD activity varies depending on the exposure time on cadmium. In the hepatopancreas of fish treated with Cd alone, the content of Cu and Zn were increased and that of Fe was changed. After melatonin administration to Cd-exposed fish, a decrease in copper and zinc hepatopancreas content was noted. The present findings imply that melatonin co-treatment can effectively protect the fish against the toxic effects of cadmium on endogenous antioxidant status in hepatopancreas tissues and variations in metal concentration, such as Zn, Cu, and Fe.

Highlights

Human activity and civilization causes increasing heavy metal pollution
Fish were randomly assigned to seven groups: control group—nominally zero cadmium in water, group Mel—the fish received intramuscular implants containing 18 mg of melatonin (Ceva Santa Animale France), group blank—the fish were sham-injected, group 0.4 mgCd/L + Mel—the fish received intramuscular melatonin implants and were exposed to cadmium in water, group 0.4 mgCd/L—the fish were exposed to cadmium in water, group 4.0 mgCd/L + Mel—the fish received intramuscular melatonin implants and were exposed to cadmium in water, and group 4.0 mgCd/L—the fish were exposed to cadmium in water
In the group of females exposed to the highest Cd doses (4 mgCd/L), Cd levels were significantly higher (p < 0.05) than in the controls and other groups, at all measurements

Summary

Introduction

Human activity and civilization causes increasing heavy metal pollution. Heavy metals such as lead, mercury, zinc, or cadmium infiltrate the water environment with surface runoff or industrial and agricultural wastewater. Heavy metals are not biodegradable but are absorbed and accumulated both in the water environment and in organisms that inhabit it. Cadmium is considered a major chemical pollutant of the aqueous environment and a serious threat to water organisms, especially fish (Derective 2013). Environmental exposure to cadmium may lead to the absorption of large quantities of the element, causing harm to the organism (Abalaka 2015)

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