Alterations in the Plasma Thyroid and Cortisol Hormones in Yellowfin Sea bream, Acanthopagrus latus, following exposure to Benzo(α)Pyrene

The goal of this research is to study the effect of benzoalphapyrene (BαP) as a pollutant on the plasma levels of cortisol, thyroxin (T4), and triiodothyronine (T3) hormones, and the T3/T4 ratio in the yellowfin sea bream, Acanthopagrus latus. The BαP (50 mg kg^-1) in vegetable oil was peritoneally injected. Blood samples were obtained from the treated and control groups after 3 and 72 hr, respectively. The amounts of cortisol, T3, and T4 were measured using the ELISA techniques. The results showed that during both the 3 and 72 hr BαP exposures, the T4 hormone levels significantly decreased, although the cortisol levels increased (Plt;0.05). However, the T3 hormone levels and T3/T4 ratios compared with their control groups showed a significant difference just after 72 hr (Plt;0.05). The disruptive effects of the BαP exposure on T4 was stronger than that on the T3, being more evident in longterm stress. Thus, the BαP exerts a significant effect on the thyroid endocrine system and consequently on fish metabolism and growth.