3,3',4,4'-TETRACHLOROBIPHENYL AFFECTS CORTISOL DYNAMICS AND HEPATIC-FUNCTION IN RAINBOW-TROUT

This study investigates the impact of 3,3',4,4'-tetrachlorobiphenyl (T CBP), a polychlorinated biphenyl (PCB) congener and cytochrome P-450 i nducer, on cortisol dynamics in rainbow trout (Oncorhynchus mykiss), T rout were given either an intraperitoneal implant of corn oil alone or corn oil containing TCBP (5 mg kg(-1) body weight) and sampled 6 week s later. TCBP-implanted fish had significantly lower condition factor and plasma glucose concentration, whereas plasma cortisol and protein, and hepatocyte protein concentration and liver ethoxyresorufin-O-deet hylase (EROD) activity was significantly higher compared with the sham group. There was no significant difference in plasma lactate and amin o acid concentration, hepatocyte glycogen content or liver cytosolic c ortisol binding affinity or capacity between the two groups. [H-3]Cort isol uptake was significantly higher in hepatocytes isolated from TCBP -treated fish compared with the sham fish, Also, our preliminary resul ts suggest that the catabolism of [H-3]cortisol by hepatocytes of TCBP -treated fish was enhanced as noted by a decrease in cortisol-specific radioactivity and an increase in tetrahydrocortisone (a cortisol meta bolite) specific radioactivity. These results support a role for TCBP in enhancing cortisol clearance by hepatocytes of trout and suggest th at toxicants like PCBs may impair the ability of trout to elicit a phy siological response normally associated with cortisol stimulation.