METABOLIC EFFECTS OF CORTISOL TREATMENT IN A MARINE TELEOST, THE SEA RAVEN

Sea raven (Hemitripterus americanus) given intraperitoneal implants of coconut oil containing cortisol (50 mg kg(-1)) and sampled 5 days lat er had plasma cortisol, glucose and urea concentrations higher than in a sham-implanted group, No differences in plasma ammonia, free amino acid or fatty acid concentrations were apparent between the cortisol- and sham-treated groups, There was no change in hepatic glycogen conte nt, whereas glutamine synthetase, allantoicase, arginase, aspartate am inotransferase, tyrosine aminotransferase, alanine aminotransferase, g lutamate dehydrogenase, phosphoenolpyruvate carboxykinase and 3-hydrox yacylcoenzyme A dehydrogenase activities were higher in the cortisol-t reated fish liver compared with the sham-implanted fish, On the basis of these general increases in enzyme activities, our results suggest t hat cortisol stimulates nitrogen metabolism in the sea raven, Amino ac id catabolism may be a major source of substrate for gluconeogenesis a nd/or oxidation, while fatty acid mobilization may provide the fuel fo r endogenous use by the liver in cortisol-treated sea raven, These res ults further support the hypothesis that cortisol plays a role in the regulation of glucose production in stressed fish.