Petroleum increases sensibility to chlorpyrifos in liver rainbow trout

DE ANNA JULIETA SOLEDAD; LEGGIERI LEONARDO RAMÓN; TORRES WALTER; VENTURINO ANDRÉS; LUQUET CARLOS MARCELO

Córdoba

Congreso; VI Congreso Argentino de SETAC; 2016

SETAC Argentina

In natural environments, fish could be simultaneously exposed to several pollutants, resulting in overlapped effects on their detoxification systems. It is known that CYP1A expression level is induced in fish exposed to polycyclic aromatic hydrocarbons from petroleum and that chlorpyrifos (CPF) is activated to chlorpyrifos-oxon through CYPs by a desulfuration reaction. This process is called activation, since the oxon derivative is the most active and less stable form. The CPF-oxon inhibits CYP activity itself and other enzymes, including carboxylesterases (CE) and acetylcholinesterase (AChE) by binding to non-substrate sites. Pre-exposure to petroleum before pesticide exposure would lead to enhanced CPF activation with the consequent increase in toxicity. We hypothesize that water accommodated fraction of petroleum (WAF) enhances CPF toxicity in fish. Juvenile rainbow trout Oncorhynchus mykiss were exposed to 5% WAF in vivo for 48 h and, then, the extirpated livers were exposed to 20 µg/L chlorpyrifos ex vivo for 1 h and subsequently assayed for CE, AChE, and glutathione S-transferase (GST) activities. As expected, CE activity inhibition by CPF was enhanced in the livers of WAF pre-treated fish (~26%) with respect to pre-treatment controls (15%, t = 3,057, P < 0.05), while AChE was inhibited by CPF irrespectively of the WAF pre-treatment. GST activity was not affected by WAF and increased CPF treatment in from both, WAF pre-treated (30%) and control fish (57%; F = 8.14, P < 0.01). Our results show an increased sensibility to CPF (CEs activities) after WAF exposure in the liver of O. mykiss. Our findings suggest possible synergistic effects between petroleum components and pesticides.