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Journal Article 
Neurotoxicity of benzo[a] pyrene and its effects on heat stress protein 70 and heat stress protein 90β in brain tissue of mice 
Tu, BJ; Wang, Y; Wu, TC 
Background: Benzo[a] pyrene(BaP) is kind of polyaromatic hydrocarbon which is a chemical pollutant extensively existing in living and productive environments. It is found overseas that it has neurotoxic effects under certain conditions. Objective: To study the neurotoxicity of BaP and its effects on expression of two heat stress proteins(HSPs) HSP70 and HSP90β in brain tissue of mice. Design: Randomized case control study of experimental animals. Setting: Laboratory of thermobiology and molecular toxicology of a unversity, department of preventive medicine of a university. Materials: The experiment was conducted in the Thermobiology and Molecular Toxicity Laboratory, Tongji Medical College, Huazhong Science and Technology University. Fifty male Kunming mice were randomly divided into 5 groups with each of 10 mice including 3 administrated groups, 1 vehicle group and 1 control group. All mice in 3 exposed groups were intraperitoneally administrated BaP dissolved in corn oil at dose levels of 7. 8 mg/kg, 3.2 mg/kg and 1.3 mg/kg respectively for four times per week. The mice in vehicle group received an equal volume of corn oil and the mice in control group received no additional treatment. Methods: The signs of neurotoxicity in each group were examined and recorded during the administration. At the end of 8-week administration, the brains were excised to calculate brain tissue organ coefficient. Western blot method was used to assay the HSP70 and HSP90β. Main outcome measures: Effects of BaP on HSP70 and HSP90β in brain tissue of mice. Results: 1 The mass of brain tissue in mice of middle and high dose of Bap exposure groups was much lower than that of control group(P < 0.01, P < 0.001) while the organ coefficient of high dose group was much lower than that of other groups(P < 0.001). 2 The expressive change of HSP70 was characterized by greatly increased expression in low dose group while the relative expression of HSP90β was increased in middle and high dose groups. Conclusion: BaP has certain neurotoxic effects. With the increase of toxic dose, the expression of HSP90β increases which can be used as signal of toxic damage under certain conditions.