Tributyltin (TBT), a toxic contaminant in aquatic environments, has bio-accumulated in aquatic food webs throughout the world and can be found at toxic levels in some biota. However, the molecular mechanisms and effects of TBT are not fully understood. The aim of the present study was to investigate the effect of long-term exposure of TBT on cytochrome P450 (CYP450) 1 regulation and heat-shock proteins (HSPs) profiling in brain of freshwater teleost. The effects of long-term exposure to TBT on mRNA expression of cytochrome P450 (CYP450) 1 family genes and ethoxyresorufin O-deethylase (EROD) activity in the brain of common carp were evaluated, as well as HSP 70 level. Fish were exposed to sublethal concentrations of TBT (75 ng/L, 0.75 μg/L and 7.5 μg/L) for 15, 30, and 60 days. Based on the results, long-term exposure (more than 15 days) to TBT could lead to obvious physiological-biochemical responses (based on EROD activity, HSP 70 level and CYP450 1 family genes expression). The mRNA expression of CYP450 1 family genes (CYP1A, CYP1B, CYP1C1 and CYP1C2) suggested that CYP1A was to accommodate most EROD activity in fish, but other CYP450 forms also involved in this proceeding. Thus, the measured physiological responses in fish brain could provide useful information to better understand the mechanisms of TBT-induced bio-toxicity and could be used as potential biomarkers for monitoring the TBT pollution in the field.

Observation Station for Fishery Resource and Environment in Upper Middle Reaches of Yangtze River Yangtze River Fisheries Research Institute Chinese Academy of Fishery Sciences Wuhan 430223 China

Observation Station for Fishery Resource and Environment in Upper Middle Reaches of Yangtze River Yangtze River Fisheries Research Institute Chinese Academy of Fishery Sciences Wuhan 430223 China College of Fisheries Huazhong Agricultural University Wuhan 430070 Hubei China

Observation Station for Fishery Resource and Environment in Upper Middle Reaches of Yangtze River Yangtze River Fisheries Research Institute Chinese Academy of Fishery Sciences Wuhan 430223 China Faculty of Fisheries and Protection of Waters South Bohemian Research Center of Aquaculture and Biodiversity of Hydrocenoses University of South Bohemia in Ceske Budejovice Zátiší 728 2 389 25 Vodňany Czech Republic

Observation Station for Fishery Resource and Environment in Upper Middle Reaches of Yangtze River Yangtze River Fisheries Research Institute Chinese Academy of Fishery Sciences Wuhan 430223 China Key Laboratory of Aquatic Science of Chongqing School of Life Science Southwest University Chongqing 400715 China

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