Evaluation of seasonal changes of serum and plasma estradiol-17β, progesterone and testosterone in dolphins (Tursiops truncatus) by chemiluminescence

Aim: The purpose of the research was to test and validate an innovative and safe chemiluminescence method to evaluate sexual hormones in serum and plasma samples of Tursiops truncatus. Materials and Methods: The research was performed on 9 bottlenose dolphins entertained in Oltremare and in Zoomarine aquatic parks, sampled by the tail vein or from the ventral one and an ultrasound monitoring, throughout a 6 months period. Blood samples were analyzed using a chemiluminescence method. Data obtained were compared to radioimmunoassay and enzyme immuno assay reference data, with the purpose to test and validate this method, through the calculation of the coefficient of variability, and its reliability on serum and plasma samples. A one-way analysis of variance was applied to test the effect of time on serum and plasma hormonal change. Results: Mean concentrations of estradiol-17β in serum were equal to 149.07±6.82 pmol/L, and in plasma equal to 159.14±12.99 pmol/L; mean values of progesterone in serum were equal to 0.69±0.05 pmol/L, and in plasma equal to 0.64±0.05 pmol/L; mean values of testosterone in serum were equal to 44.43±14.42 nmol/L, and in plasma equal to 48.99±11.20 nmol/L Conclusion: It would be interesting to widen the investigations on a larger number of subjects, in which the relationship between the concentrations of free and binding steroid hormones, with the dosing of binding proteins, would define the physiological ranges of reference in the T. truncatus.