Food deprivation alters osmoregulatory and metabolic responses to salinity acclimation in gilthead sea bream Sparus auratus

• Published in: Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology Vol. 176; no. 5; pp. 441 - 452
• Main Authors: Polakof, Sergio, Arjona, Francisco J, Sangiao-Alvarellos, Susana, Martín del Río, María P, Mancera, Juan M, Soengas, José L
• Format: Journal Article
• Language: English
• Published: Germany Springer Nature B.V 01.06.2006; Springer Verlag
• Subjects: Acclimatization; Acclimatization - physiology; Amino acids; Animals; Aquaculture; Brackish; Energy Metabolism - physiology; Fish; Food; Food Deprivation - physiology; Glucose - metabolism; Hydrocortisone - blood; Life Sciences; Male; Marine; Metabolites; Osmoregulation; Saline water; Salinity; Sea Bream - physiology; Seawater; Sodium Chloride; Sodium-Potassium-Exchanging ATPase - physiology; Sparus aurata; Water-Electrolyte Balance - physiology
• ISSN: 0174-1578; 1432-136X
• DOI: 10.1007/s00360-006-0065-z

The influence of acclimation to different environmental salinities (low salinity water, LSW; seawater, SW; and hyper saline water, HSW) and feeding conditions (fed and food deprived) for 14 days was assessed on osmoregulation and energy metabolism of several tissues of gilthead sea bream Sparus auratus. Fish were randomly assigned to one of six treatments: fed fish in LSW, SW, and HSW, and food-deprived fish in LSW, SW, and HSW. After 14 days, plasma, liver, gills, kidney and brain were taken for the assessment of plasma osmolality, plasma cortisol, metabolites and the activity of several enzymes involved in energy metabolism. Food deprivation abolished or attenuated the increase in gill Na+,K+-ATPase activity observed in LSW- and HSW-acclimated fish, respectively. In addition, a linear relationship between renal Na+,K+-ATPase activity and environmental salinity was observed after food deprivation, but values decreased with respect to fed fish. Food-deprived fish acclimated to extreme salinities increased production of glucose through hepatic gluconeogenesis, and the glucose produced was apparently exported to other tissues and served to sustain plasma glucose levels. Salinity acclimation to extreme salinities enhanced activity of osmoregulatory organs, which is probably sustained by higher glucose use in fed fish but by increased use of other fuels, such as lactate and amino acids in food-deprived fish.