Influence of 11-ketotestosterone, 17beta-estradiol, and 3,5,3'-triiodo-L-thyronine on distribution and metabolism of carotenoids in Arctic charr, Salvelinus alpinus L

摘要

This investigation examines the influence of implants containing 11-ketotestosterone (11KT), 17beta-estradiol (E2) and 3,5,3'-triiodo-L-thyronine (T3) on astaxanthin metabolism in sexually immature individually tagged Arctic charr. The fish (initialaverage weight 427 g) were maintained in freshwater for 40 days, and received weekly intraperitoneal implants of oil-based solutions containing either 11 KT, E2 or T3 at concentrations of 0.1, 1.0 and 0.1 mg/100 g body weight (BW) respectively. The control fish were given the oil medium alone (0.2 ml/100 g BW). The diet contained～50 mg astaxanthin/kg. Carotenoid composition was monitored in plasma, fillet, liver and skin, and 11 KT, E2 and testosterone (T) levels in plasma. All hormone treatments reduced plasma T compared to the control. E2-treated fish had a higher (P< 0.05) hepatosomatic index (HSI) than the other treatments. Hormone treatment did not influence gonadosomatic index (GSI). T3 administration induced a silvery skin appearance. The fillet and plasma carotenoid content decreased during the experiment. 11 KT reduced astaxanthin and idoxanthin concentrations of plasma and fillets and increased the amount in liver and skin, compared with the other treatments. The relative proportion of astaxanthin to idoxanthin was higher in the control fish and T3 implanted fish, than in fish implanted with 11 KT or E2 (P< 0.05). Fish treated with E2 had the highest skin carotenoid concentration. Male fish had significantly higher carotenoid content in plasma, fillet and skin than female fish.