Effect of metals, with special attention of Cd, content of the Svitava and Svratka rivers on levels of thiol compounds in fish liver and their use as biochemical markers.

OBJECTIVES: The aim of this study was to assess the effect of metals, with special attention of cadmium (Cd), content of the Svitava and Svratka rivers (Czech Republic) on levels of thiol compounds such as metallothioneins (MT), glutathione (GSH/GSSG), and cysteine (Cys) concentrations in chub (Leuciscus cephalus L.) liver and their use as biomarkers.

DESIGN: Levels of thiol compounds in fish liver were determined by the differential pulse voltammetry Brdicka reaction. Cadmium content in L. cephalus liver was measured by atomic absorption spectometry (AAS) with electrothermal atomization. The contents of thiols and Cd were correlated with the Cd and metals content of river bottom sediments.

RESULTS: Results were inconsistent with those of experimental studies. Correlations between liver Cd content and MT, Cys, GSSG were not significant in any locality (p > 0.05). Cd liver content was negatively (p< 0.05) correlated with GSH at one (Zidlochovice) of the seven tested sites. GSH and GSSG correlated negatively in five localities (p > 0.05). Correlations between Cd in sediment and Cys and GSSG (p > 0.05), and MT was negative (p< 0.05). The relationship between sum of metals value and MT was negative (p< 0.05), similarly with GSSG (p > 0.05).

CONCLUSION: Many factors influence content of MT, GSH, and GSSG, and data for Cd were equivocal. Monitoring the aquatic ecosystem to identify metal content using thiol compounds in fish liver as biomarkers is complex. More relevant data including laboratory experiments will be required to assess most of the factors influencing thiols and their relevance to Cd contamination.