Figure 4. CP-Parkin protects neuronal cells from 6-OHDA-induced apoptosis.

(A) Suppression of apoptosis in dopaminergic CATH.a cells. CATH.a cells at 5% (Low) or 70% (High) confluence were incubated with 50 µM 6-hydroxydopamine (6-OHDA, Agonist) for 1 hr, treated for 2.5 hrs with 2.5 µM HP or HPM₁₃ and assessed for apoptosis by TUNEL staining. The micrographs (left panels) are representative of three independent experiments, plotted (right panels) as means ± S.D. Experimental differences between groups were assessed by a Student’s two-paired t-test (*p<0.001). (B) Suppression of apoptosis in SH-SY5Y cells. Apoptosis in SH-SY5Y treated with 6-OHDA with and without PM₁₀ was assessed as described in (A). (C) HPM₁₃ enhances dopamine release from CATH.a cells. The cells were incubated with 80 µM tyrosine for 24 hrs, treated for 5 hrs with 2.5 µM HP or HPM₁₃, and levels of secreted dopamine were measured by ELISA. The data are presented as means ± S.D. of 4 independent experiments. Experimental differences between groups were assessed by a Student’s two-paired t-test (*p<0.01 and **p 0.05).