Figure 5.

Protection against Mn3+, H2O2, and AM induced dopaminergic PC12 cell death by tea polyphenols and other agents. Dopaminergic PC12 cells were challenges with 200 or 300 μM Mn³⁺ or 300 μM H₂O₂ overnight or 100 μM AM 3 h respectively in the presence or absence of various agents. Cells without any challenges are set as control. *, at least p < 0.05, compared with cell viability of control cells. #, at least p < 0.05, compared with cell viability of cells challenged with stressors only. (A,B), The Mn³⁺ induced cell toxicity are dependent on endogenous DA level in PC12 cells. (A) Influence on PC12 cell viability by tyrosine hydroxylase (TH) overexpression or knockdown under Mn³⁺ overnight challenge. PC12 cells were transfected with rat-TH or TH shRNA vectors overnight respectively, before subsequent 200 μM Mn³⁺ overnight challenge. (B) Influence on DA level in PC12 cells by TH overexpression or knockdown. (C–E) Protection of PC12 cells against 300 μM Mn³⁺ overnight challenges induced toxicity by different agents. (C) Protection by 50 and 500 μM CAF, NICO, MAN, VE, VC, GSH, and l-cys. (D) Protection by 25 and 100 μM GA, EGC, EGCG, TF, and TA. (E) Protection by 250 μM GSH, l-cys and tea polyphenols. (F–H), protection against 300 μM H₂O₂ or 100 μM AM challenges induced toxicity by various agents. (F) Protection against H₂O₂ induced toxicity by 250 and 1000 μM CAF, NICO, and MAN. (G) Protection against H₂O₂ induced toxicity by 250 μM agents. (H) Protection against 100 μM AM induced toxicity by 250 μM agents.