Effects of DHA on MeHg-induced changes in the mRNA and protein expression levels of Bcl-2 and Bax. Reverse transcription-quantitative PCR was used to detect changes in the mRNA expression levels of (A) Bcl-2 and (B) Bax, and (C) Bcl-2/Bax ratio in PC12 cells pretreated with DHA (5, 10 and 20 µmol/l) followed by exposure to 2.5 µmol/l MeHg for 48 h. Relative expression levels were normalized to the corresponding GAPDH levels. (D) Western blotting demonstrated the dynamic changes in the protein expression levels of (E) Bcl-2 and (F) Bax, and (G) Bcl-2/Bax ratio in PC12 cells pretreated with DHA (5, 10 and 20 µmol/l) followed by exposure to 2.5 µmol/l MeHg for 48 h. Protein band intensity was analyzed after normalization to the corresponding GAPDH levels, and the relative ratios were analyzed after normalization to the corresponding control group. Data are presented as the mean ± SD, n=3. ***P<0.001 vs. control group; #P<0.05, ##P<0.01 and ###P<0.001 vs. MeHg group. MeHg, methylmercury; DHA, docosahexaenoic acid.