Handling stress does not affect the expression of hepatic heat shock protein 70 and conjugation enzymes in rainbow trout treated with β-naphthoflavone

Abstract

A response in heat shock protein 70 (hsp 70) expression in the β-naphthoflavone (BNF) treated rainbow trout ( Oncorhynchus mykiss) corresponded to altered metabolic status of the liver as evidenced by the lower phosphoenolpyruvate carboxykinase (PEPCK), lactate dehydrogenase and 3-hydroxyacylcoA dehydrogenase activities. The BNF-induced increase in hsp70 levels and conjugation enzyme activities (phase I and phase II) were not modified by handling stress. Indeed handling stress did not affect either hsp 70 levels or conjugation enzyme activities in trout liver. The decrease in hepatic PEPCK activity in the BNF group may be responsible for the attenuation of the increase in liver glucose concentration after a 3 min handling stress in this species, suggesting that BNF affects liver gluconeogenic capacity in this species. Handling stress elicited a plasma cortisol and glucose response in both the sham and BNF group, however, the cortisol response with BNF was erratic compared with the sham, implying alterations in the cortisol dynamics post-stress. These results show for the first time that BNF affects cellular metabolic responses to stress and suggests the possibility of using hsp 70 as a biomarker for toxic effects in trout.