Response of Melanomacrophage Centers in Yellowfin Seabream (Acanthopagrus latus) Immune Organs as an Immunohistological Biomarker in Short-term Exposure to Phenanthrene

Background: The aim of this study was to assess the changes in plasma levels of antioxidant enzymes and melano-macrophage centers (MMCs) in immune tissues as biomarkers of yellowfin seabream (Acanthopagrus latus) exposed to phenanthrene (Phe) for 14 days. Methods: The research was carried out at Khorramshahr University of Marine Science and Technology, Khorramshahr, Iran in Jan 2016. Thirty-six immature fish were intraperitoneally injected with coconut oil (10 μl/g-bw) containing Phe (70mg/kg-bw) and compared with control group (without injection). Then tissue and blood samples were obtained at 1, 4, 7 and 14 d after injection. Results: The SOD and CAT activity showed a significant decrease in fish exposed to Phe up to day 7, then activity increased at day 14 in Phe-treated fish (P<0.05). The size and number of MMCs in treated fish in spleen and head kidney were higher than control. Conclusion: Changes in these parameters (SOD, CAT, and MMCs) might be used as useful biomarkers for evaluating immunosuppressive Phe in fish.