Xenobiotic metabolizing enzymes in uninduced and induced rainbow trout (Oncorhynchus mykiss): Effects of diets and food deprivation

The effects of diet composition and ration on biotransformation enzymes and stress parameters in rainbow trout, Oncorhynchus mykiss

“…Although no effects of dietary nutrient content or ration size were observed in this study, other studies have demonstrated that both dietary nutrient content and dietary quantity may have significant effects on an animal's stress response (Barton et al, 1988;Farbridge and Leatherland, 1992) and on detoxification ability (Ankley et al, 1989, Vigano et al, 1993Blom et al, 2000). However, results of these studies have provided equivocal results to the degree of the effects and demonstrated that more research is needed in this area.…”

“…In the present study, the activities of the CYP 1Al-mediated reaction, EROD, and the conjugating enzyme, GST, were maintained at constant levels all ration levels suggesting the importance of these systems under the various dietary treatments. This is further supported by the maintenance of these, and other biotransformation enzymes, including cytochrome P450, benzo(a)pyrene hydroxylase (AAH), UDP-glucuronosyl transferase (UDP-GT), during periods of teleost starvation (Buhler and Rasmusson, 1968;Andersson et al, 1985a;Vigano et al, 1993). The maintenance of biotransformation enzyme activities under these conditions is expected to have adaptive significance for fish, which often undergo recurring periods of starvation, while mammals challenged with starvation demonstrate extremely variable liver cytochrome P450 dependent activities (Campbell and Hayes, 1974).…”

“…The effects of depriving teleosts of food for periods between 15 days and 12 weeks on their biotransformation enzyme abilities have produced varying results (Buhler and Rasmusson, 1968;Andersson et at., 1985a;Vigano et at., 1993;Wall and Crivello, 1999;Blom et al, 2000). After two weeks of starvation, juvenile rainbow trout biotransformation enzymes including, hepatic 7-ethoxyresorufin-0-deethylase (EROD), glutathione S-transferase (GST) and benzo(a)pyrene hydroxylase (AHH) activities were maintained while UDP glucuronyltransferase (UDP-GT), and glutathione reductase (GR) activities were significantly decreased and cytochrome P450 activity was increased when compared to fish fed ad libitum (Vigano et al, 1993). In other studies with rainbow trout (Huuskonen et al, 1995) and winter flounder (Pleuronectus amencanus) (WaH and Crivello, 1999), EROD activity was significantly reduced after 2 weeks of starvation.…”

“…A small number of experiments using fish have compared the effects of commercial diets on biotransformation enzymes but these have not systematically altered dietary composition. Nevertheless, consumption by fish of these different commercial diets, which varied in all aspects of proximate composition, resulted in the reduction and induction of assorted biotransformation enzymes depending on which diet was received (Vigano et al, 1993). Although differences in enzyme activity…”

Energy allocations to xenobiotic transport and biotransformation reactions in rainbow trout (Oncorhynchus mykiss) during energy intake restriction

“…It is not surprising that in the present study LSI responded more rapidly than BW to changing dietary conditions. These results are in agreement with other literature on feed-deprived rainbow trout, in which BW decreased within 4 to 6 weeks, and reductions in LSI became significant within much shorter time frames (2 days to 3 weeks of dietary restriction) (Farbridge and Leatherland 1992;Vigano et al 1993;Blom et al 2001;Mattson et al 2001). The rapid change in LSI in early fasting is likely due to a cortisol-induced mobilization of liver glycogen and lipid stores; as trout fasted for 3 to 4 weeks exhibit enhanced gene expression of key enzymes in gluconeogenesis, and a down-regulation of glycolysis and the pentose phosphate pathways (Blom et al 2000;Simpkins and Hubert 2003;Johansen and Overturf 2006;Salem et al 2007).…”