We investigated short-term effects (up to 24 h) of air exposure and confinement, and long-term effects (up to 11 days) of confinement, to elucidate signalling pathways in the stress response of gilthead sea bream Sparus aurata L. Plasma glucose and lactate were taken as indicators of sympathetic activation, and alpha-melanocyte stimulating hormone (alpha-MSH), adrenocorticotrophic hormone (ACTH) and cortisol as indicators of activation of the brain-pituitary-interrenal (BPI) axis. Air exposure for 3 min resulted, within 30 min, in an increase in plasma concentrations of cortisol, alpha-MSH, glucose, lactate, osmolality and plasma Na, Cl and Mg. Plasma ACTH and beta-endorphin and plasma K, Ca and P did not change. We conclude that air exposure mainly activates the brain-sympathetic-chromaffin cell (BSC) axis. In fish confined at a density of 70 kg/m(3) (compared with 4 kg/m(3) in controls), cortisol, ACTH and alpha-MSH increased within 1 h, indicating activation of the BPI axis. Plasma glucose, Na, Cl and Mg increased with an 8 h delay compared with the response to air exposure. No changes in plasma lactate, osmolality, K, Ca and P were observed. Long-term confinement induced a biphasic cortisol response with peaks at 1 h and at 2 and 3 days. A gradual increase in plasma beta-endorphin concentrations peaked at 7 days; the concentration of alpha-MSH increased rapidly within 1 h and then declined to control values 4 days after the onset of confinement. No changes in ACTH were detected. Our data provide evidence that a stressor-specific activation of the BSC and BPI axes may occur in Sparus aurata.

This article has been cited by other articles:

				J. W. Mandelman and M. A. Farrington The physiological status and mortality associated with otter-trawl capture, transport, and captivity of an exploited elasmobranch, Squalus acanthias ICES J. Mar. Sci., January 1, 2007; 64(1): 122 - 130. [Abstract] [Full Text] [PDF]

				W. Abbink, G. S. Bevelander, X. Hang, W. Lu, P. M. Guerreiro, T. Spanings, A. V. M. Canario, and G. Flik PTHrP regulation and calcium balance in sea bream (Sparus auratus L.) under calcium constraint J. Exp. Biol., September 15, 2006; 209(18): 3550 - 3557. [Abstract] [Full Text] [PDF]

				M. R. Markham and P. K. Stoddard Adrenocorticotropic Hormone Enhances the Masculinity of an Electric Communication Signal by Modulating the Waveform and Timing of Action Potentials within Individual Cells J. Neurosci., September 21, 2005; 25(38): 8746 - 8754. [Abstract] [Full Text] [PDF]

				J. R. Metz, E. J. W. Geven, E. H. van den Burg, and G. Flik ACTH, {alpha}-MSH, and control of cortisol release: cloning, sequencing, and functional expression of the melanocortin-2 and melanocortin-5 receptor in Cyprinus carpio Am J Physiol Regulatory Integrative Comp Physiol, September 1, 2005; 289(3): R814 - R826. [Abstract] [Full Text] [PDF]

				W. Abbink, G. S. Bevelander, J. Rotllant, A. V. M. Canario, and G. Flik Calcium handling in Sparus auratus: effects of water and dietary calcium levels on mineral composition, cortisol and PTHrP levels J. Exp. Biol., November 1, 2004; 207(23): 4077 - 4084. [Abstract] [Full Text] [PDF]

				R.G. Lea, D. Howe, L.T. Hannah, O. Bonneau, L. Hunter, and N. Hoggard Placental leptin in normal, diabetic and fetal growth-retarded pregnancies Mol. Hum. Reprod., August 1, 2000; 6(8): 763 - 769. [Abstract] [Full Text] [PDF]