EFFECTS OF A COMPLEX MIXTURE OF CHEMICAL CONTAMINANTS ON HEPATIC GLUTATHIONE, L-CYSTEINE AND γ-GLUTAMYLCYSTEINE SYNTHETASE IN ENGLISH SOLE (PLEURONECTES VETULUS)

摘要

The effects of chemical contaminants on concentrations of hepatic glutathione (GSH), cysteine (L-Cys), and the activity of γ-glutamylcysteine synthetase (γ-GCS) were assessed in English sole (Pleuronectes vetulus) in the laboratory and in fish from the Duwamish Waterway, a contaminated urban site in Puget Sound, Washington. In the laboratory studies, fish from a nonurban (reference) site were exposed to an organic-solvent extract of sediment from the Duwamish Waterway. Hepatic GSH concentrations significantly increased at 3 d after exposure to the extract at 1,000 g sediment extracted/kg fish. At this time point, hepatic GSH showed a dose-dependent increase at dosages ranging from 300 to 1,600 g sediment extracted/kg fish, whereas fish exposed to a reference sediment extract showed no increase. Moreover, the increases in GSH in fish exposed to the contaminated sediment extract were not accompanied by changes in either L-Cys concentrations or γ-GCS activity. Similarly, fish sampled directly from the Duwamish Waterway showed increased GSH concentrations but showed no significant differences in L-Cys levels or γ-GCS activity compared to fish from a reference site. These results substantiate that hepatic GSH in fish is responsive to chemical contaminant exposure and further support its use as a biomarker in environmental monitoring studies. The findings also indicate that L-Cys availability and induction of γ-GCS were not major factors in the increase of hepatic GSH in contaminant-exposed English sole.