Abstract
Fish liver ethoxyresorufin-O-deethylase (EROD) activity is widely used as biomarker of exposure to chemicals such as polycyclic aromatic hydrocarbons (PAHs). It is known that endocrine system plays a major role in fish stress mechanism. Despite the considerable scientific information about steroid hormone’s response, namely cortisol and 17ß-estradiol (E2), to stress situations, little is known about the influence of these hormones on enzymes involved on the biotransformation process. Thus, this study aimed to assess the in vitro effects of environmentally relevant concentrations of benzo[a]pyrene (B[a]P) (0.1, 0.3, 0.9, and 2.7 µM) and of two steroid hormones (cortisol and 17ß-estradiol) in a physiologically relevant concentration (5.997 ng/mL), alone or in combination, on Anguilla anguilla liver microsomal EROD activity, previously induced by 4 mg/kg β-naphthoflavone intraperitoneal injection. Hepatic microsomes in vitro exposure to the tested B[a]P concentrations induced a dose response inhibition of EROD activity, whereas exposure to cortisol significantly induced the activity of this enzyme. The steroid hormones were able to decrease the inhibitory effects of B[a]P on microsomal EROD activity, thus revealing a protective effect of these hormones over enzyme activity inhibited by contaminants.
Highlights
Polycyclic aromatic hydrocarbons (PAHs) are one class of persistent organic contaminants present in the environment [1] mainly due to anthropogenic inputs, their environmental release may be related to natural sources [2]
All tested B[a]P concentrations showed a significant increase in EROD activity in the presence of cortisol, when compared to B[a]P individual exposure, with the highest increase observed for 0.1 μM B[a]P
The presented study aimed to assess if environmentally relevant concentrations of B[a]P (0.1, 0.3, 0.9, and 2.7 μM), as well as a physiologically relevant concentration of cortisol and E2 (5.997 ng/mL), alone or in combination, had a significant impact on EROD activity
Summary
Polycyclic aromatic hydrocarbons (PAHs) are one class of persistent organic contaminants present in the environment [1] mainly due to anthropogenic inputs, their environmental release may be related to natural sources (e.g., forest fires, volcanic emissions, natural oil seeps, coal deposits, plant debris) [2]. Benzo[a]pyrene (B[a]P) is a nearly ubiquitous PAH contaminant categorized in the highest human carcinogenic risk level, posing risk to human health and ecosystems. As such, it is often used as a surrogate for general PAH contamination [5]. Aquatic organisms can be exposed to contaminated sediments and waters where PAHs are taken up via various pathways [6] and converted into sets of metabolites by biotransformation phase I enzymes, namely cytochrome CYP1A dependent monooxygenase enzymes, such as ethoxyresorufin-O-deethylase (EROD) [7,8]. EROD activity is frequently used as a biomarker of exposure to PAHs and structurally related compounds, such as ß-naphthoflavone (BNF) [8,10]. Intraperitoneal (i.p.) injection with naphthoflavone (BNF) consistently resulted in the highest EROD fold induction (often higher than 20-fold relative to control fish) and is a reliable positive control for EROD activity investigations [8]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
