Аннотация:Acute handling stress resulted in significant elevation of plasma cortisol and lactate concentrations within 30 min in both fed and food-deprived rainbow trout (Oncorhynchus mykiss), indicating a typical stress response. Plasma glucose levels rose immediately (30 min) poststress in the food-deprived group, while there was a delayed response (2 h) in the fed group. The low liver glycogen content and total glycogen phosphorylase (GPase) and glycogen synthase (GSase) activities in the food-deprived group indicated an overall depression in glycogen metabolism. Acute handling stress maintained liver glycogen stores for up to 4 h in the food-deprived group, but the combined effects of limited substrate and increased energy demand necessitated mobilization of liver glycogen in the food-deprived group, but not in the fed group. This increased glycogen mobilization in the food-deprived group coincided with a secondary elevation in plasma cortisol concentration 4 h poststress. The results indicated that food-deprived rainbow trout were more sensitive to stress of handling and mobilized glycogen stores to meet the energy demand imposed by the stressor. The elevated plasma cortisol levels noted during acute handling stress could play an important role in energy partitioning, metabolically adapting the fish to handling stress.
