The Possible Role of Endogenous Ouabain as a Distress Marker in Marine Mammals and Reptiles
The present study is part of a larger project that includes the study of human models. The title of the project is: “Translational approach to the study of the neuroprotection against to hypoxia in the bottlenose dolphin (Odontoceti), in Caniformia, in the loggerhead sea turtle (Testudines) versus pulmonary hypertension patients versus élite breath-hold divers”.
The plasmatic endogenous ouabain (EO) is a stress hormone produced by adrenal gland with potential hemodynamic and renal effects.1 EO is associated, in humans, with adverse cardiovascular outcomes.2 Recent studies, in vivo and in vitro, have highlighted other possible roles of the EO (i.e., cardioprotection,3 brain protection against traumatic injury4). The role of EO in marine mammals and reptiles is currently unknown.
For the present study the blood samples (N=31) were collected from: 16 bottlenose dolphins (Tursiops truncatus), one common seal (Phoca vitulina), one gray seal (Halichoerus grypus), one California sea lion (Zalophus californianus), one Afro-Australian Fur Seal (Arctocephalus pusillus pusillus) kept under human care, and 11 wild loggerhead sea turtles (Caretta caretta).
The preliminary results support the role of EO as distress hormone also in animals, in particular in the loggerhead sea turtles rescued after stranding events and hosted to the Rescue Centers. In the bottlenose dolphins and in the loggerhead sea turtles, the EO concentrations seems to be correlated to the body size (total length and weight).
Although further studies are required, these results give some hints for possible therapeutic and diagnostic approaches.
Acknowledgements
The authors wish to thank Dr. Vincenzo Olivieri, DVM, PhD; Dr. Chiara Profico, DVM; and Dr. Sergio Guccione of Centro Studi Cetacei no-profit Association (the first Italian National Stranding Network); Dr. Daniele Giansante of Istituto Zooprofilattico Sperimentale Abruzzo–Molise “Giuseppe Caporale” (public health institute); Prof. Davide Bellotti of University of Ferrara (FE), Italy; the ownership of Zoomarine Italia of Torvaianica (Rome); the marine mammal staff of Oltremare and Acquario di Genova.
The authors wish also to thank all the trainers who have cooperated to animal blood sampling, and Dr. Nunzia Casamassima for technical assistance during the study.
* Presenting author
Literature Cited
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