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AB prepress abstract   -  DOI: https://doi.org/10.3354/ab00734

High hydrostatic pressure effects on arginine vasotocin levels in fish

Arnau Rodríguez-Illamola*, Jesús M. Míguez, João Coimbra, Jonathan M. Wilson

*Corresponding author:

ABSTRACT: The present study investigates the response of the hormone arginine vasotocin (AVT), the non- mammalian antidiuretic hormone, to the acclimation of fish to high hydrostatic pressure (5.1 MPa). Two fish species with different osmoregulatory strategies, the lesser spotted dogfish Scyliorhinus canicula, a marine osmoconforming chondrichthyan species adapted to migrate to deep waters and the rainbow trout, Oncorhynchus mykiss, a pressure sensitive freshwater species, were selected for the study. Fish were exposed to hydrostatic pressures of either 0.1 MPa (control) or 5.1 MPa in hydrostatic chambers for up to two weeks at their appropriate salinities. Plasma cortisol was measured in trout and plasma chloride, sodium and potassium were measured in both fish species. Any of these parameters changed after the high-pressure conditions. A transient high level of plasma arginine vasotocin was found in dogfish and in trout after 1 and 3 days of exposure to high hydrostatic pressure, which returned to basal levels by 14 days of exposure. In contrast, pituitary arginine vasotocin content was reduced after short-term exposure in dogfish, while in trout lower expression was found in high pressure than in control conditions, independently of exposure time. In dogfish, pituitary arginine vasotocin levels recovered by 14 days under high hydrostatic pressure. No changes in plasma cortisol (trout) or ions (both species) were observed. These initial increases of the arginine vasotocin release from pituitary during fish acclimation to high pressure suggests that it consists in a physiological short-term response to reduce water loss and equilibrate ion-osmotic balance.