Acetyl salmon endorphin-like and interrenal stress response in male gilthead sea bream, Sparus aurata.
The present study investigates the role of melanotrope proopiomelanocortin-derived peptide in the interrenal stress response to different stressors in male gilthead sea bream, Sparus aurata. Plasma cortisol and acetyl salmon endorphin (acetyl s-EP), as well as pituitary acetyl s-EP contents, were measured during two stress paradigms: (a) long-term (1-month) confinement and crowding, and (b) short-term (60-min) confinement, crowding, and manipulation. In addition, naltrexone, a highly specific opioid receptor antagonist, was employed in some experimental groups to evaluate the adaptability of the opioid response to interrenal stress. In the long-term (1-month) confinement and crowding, higher plasma cortisol levels and acetyl s-EP concentrations than in the control group were found. However, although plasma cortisol levels significantly increased in both types of stress paradigm, a significant rise in plasma acetyl s-EP was observed only in the case of confinement plus crowding. These data seem to suggest a direct correlation of acetyl s-EP plasma levels exclusively in cases of specific stress, and support previous observations about the different nature of the pituitary-interrenal stress response in salmonids and in mammals. The results obtained in the short-term (60-min) experiments demonstrate the double activation of both the opioid and corticotrope systems when manipulation plus crowding was applied.
Dipartimento di Biologia MCA, Università di Camerino, di Modena, Italia.
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Mosconi
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Gallinelli
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Polzonetti-Magni
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Facchinetti
D000222:Adaptation, Physiological / Q000187:drug effects / Q000502:physiology; D000311:Adrenal Glands / Q000502:physiology; D000818:Animals; D003441:Crowding; D004723:Endorphins / Q000032:analysis / Q000097:blood*; D006854:Hydrocortisone / Q000097:blood; D008297:Male; D009271:Naltrexone / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D010473:Perciformes / Q000502:physiology*; D010902:Pituitary Gland / Q000737:chemistry / Q000187:drug effects / Q000502:physiology; D013312:Stress, Physiological / Q000503:physiopathology*
D004723:Endorphins; D009292:Narcotic Antagonists; D009271:Naltrexone; C036449:deacetyl salmon endorphin; D006854:Hydrocortisone