Hepatic mixed-function oxidase activity in rainbow trout exposed to several polycyclic aromatic compounds

Area of Science:

• Environmental toxicology
• Biochemistry
• Aquatic toxicology

Background:

• Polycyclic aromatic hydrocarbons (PAHs) are environmental contaminants.
• Microsomal liver enzymes, including mixed-function oxidases (MFOs), are crucial for metabolizing xenobiotics.
• Rainbow trout (Oncorhynchus mykiss) are a model organism for studying aquatic toxicology.

Purpose of the Study:

• To investigate the effects of various PAHs on MFO activity in rainbow trout.
• To determine the relationship between PAH bioaccumulation and MFO induction.
• To establish a threshold for B(a)P tissue concentration associated with MFO induction.

Main Methods:

• Rainbow trout were injected with different PAHs to assess MFO activity.
• Fish were exposed to solubilized PAHs (pyrene, fluoranthene, B(a)P) in water.
• Tissue concentrations of PAHs and MFO activity were measured.

Main Results:

• Chrysene, benzo(a)pyrene (B(a)P), and Aroclor 1254 induced MFO activity upon injection.
• Waterborne B(a)P exposure and subsequent bioaccumulation resulted in MFO induction.
• Bioaccumulation of pyrene and fluoranthene did not induce MFO activity.
• A tissue concentration exceeding 300 µg/kg of B(a)P was predicted to induce MFO activity.

Conclusions:

• B(a)P is a potent inducer of MFO activity in rainbow trout.
• The bioaccumulation of certain PAHs, like B(a)P, can lead to significant toxicological effects.
• A specific tissue concentration threshold for B(a)P can predict MFO induction in this species.