Whole-body levels of ACTH, alpha-MSH and cortisol in eggs and larvae of the common carp (Cyprinus carpio) were determined periodically up until 168 h after fertilisation. ACTH, alpha-MSH and cortisol immunoreactivity was detected in unfertilised eggs, and endogenous production of ACTH and alpha-MSH was observed 24 h after fertilisation and that of cortisol 36 h after fertilisation. ACTH immunoreactivity reached peak levels before hatching (56-72 h after fertilisation) and remained relatively stable thereafter, while alpha-MSH immunoreactivity started to increase after hatching. At 36 h after fertilisation, whole-body cortisol levels increased rapidly reaching peak levels at the end of hatching (72 h after fertilisation), remaining stable until the end of the experiment. From 50 h after fertilisation onwards, embryos and larvae increased their whole-body cortisol levels when subjected to handling (mechanical pressure during egg stage or netting during the larval stage). It is concluded that the pituitary-interrenal axis in carp is fully functional at the time of hatching. No indications of a stress non-responsive period after hatching were observed. To characterise ACTH and alpha-MSH immunoreactivities in carp larvae, whole-body homogenates were analysed by HPLC, with pituitary homogenates of adult carp serving as a reference. ACTH and alpha-MSH immunoreactivity in carp larvae homogenates consisted of three and two products respectively. HPLC of adult carp pituitaries revealed the presence of two ACTH immunoreactive products, which may represent a phosphorylated and a non-phosphorylated ACTH variant, while the three alpha-MSH peaks most likely represent des-acetylated, mono-acetylated and di-acetylated alpha-MSH, the latter being the predominant form. In carp larvae, however, one of the ACTH immunoreactive products co-eluted with the non-phosphorylated ACTH, while the two alpha-MSH products identified co-eluted with des-acetylated and mono-acetylated alpha-MSH, indicating that POMC processing at this stage of development is different from prohormone processing in adult fish.

This article has been cited by other articles:

				D. Alsop and M. M. Vijayan Development of the corticosteroid stress axis and receptor expression in zebrafish Am J Physiol Regulatory Integrative Comp Physiol, March 1, 2008; 294(3): R711 - R719. [Abstract] [Full Text] [PDF]

				B. D. Rodgers, G. M. Weber, K. M. Kelley, and M. A. Levine Prolonged fasting and cortisol reduce myostatin mRNA levels in tilapia larvae; short-term fasting elevates Am J Physiol Regulatory Integrative Comp Physiol, May 1, 2003; 284(5): R1277 - R1286. [Abstract] [Full Text] [PDF]

				B. A. Barton Stress in Fishes: A Diversity of Responses with Particular Reference to Changes in Circulating Corticosteroids Integr. Comp. Biol., July 1, 2002; 42(3): 517 - 525. [Abstract] [Full Text] [PDF]

				J. H. Mol, W. Atsma, G. Flik, H. Bouwmeester, and J. W. Osse Effect of low ambient mineral concentrations on the accumulation of calcium, magnesium and phosphorus by early life stages of the air-breathing armoured catfish Megalechis personata (Siluriformes: Callichthyidae) J. Exp. Biol., August 1, 1999; 202(15): 2121 - 2129. [Abstract] [PDF]