Stress alters food intake and glucosensing response in hypothalamus, hindbrain, liver, and Brockmann bodies of rainbow trout

In fish food intake is altered under stress conditions and in a fish teleost model like rainbow trout food intake is associated with the activity of the glucosensor systems Thus we aimed to evaluate the possible interaction of stress with the response of glucosensor mechanisms in rainbow trout Thus we subjected rainbow trout (via intraperitoneal injections) to normoglycaemic (control) hypoglycaemic (4 mg kg(-1) bovine insulin) or hyperglycaemic (500 mg kg 1 glucose body mass) conditions for 5 days under normal stocking density (NSD 10 kg fish mass m 3) or stress conditions induced by high stocking density (HSD 70 kg fish mass m 3) The experimental design was appropriate since hypoglycemia and hyperglycemia were observed in fish under NSD whereas in normoglycaemic fish HSD induced changes in stress-related parameters similar to those reported in fish literature such as increased levels of cortisol and glucose in plasma and decreased levels of glycogen in liver Food intake did not respond to changes in plasma glucose levels in fish under HSD conditions in contrast with the decreased food intake observed when glucose levels increased in fish under NSD conditions Moreover the changes with the increase in plasma glucose levels in parameters Involved in glucosensing in liver Brockmann bodies (BB) hypothalamus and hindbrain of fish in NSD either disappeared (DHAP and GAP levels and GK PK and GPase activities in liver glucose DHAP and GAP levels in BB glucose and DHAP levels and GK and PK activities in hypothalamus glycogen and DHAP levels and GSase activity in hindbrain) or changed (cortisol levels in plasma glycogen and GAP levels and GSase and FBPase activities in liver GK and PK activities in BB GK and PK activities in hindbrain) in fish under HSD Those changes suggest for the first time in fish the existence of an interaction between glucosensing capacity and stress The readjustment in the activity of glucosensor systems is also associated with changes in food intake resulting in an inability of the fish to compensate with changes in food intake those of circulating glucose levels as observed in fish under non-stressed conditions (C) 2010 Elsevier Inc All rights reserved