Sub-lethal concentrations of METH protected MN9D cells against 6-OHDA toxicity.

<p>Cells were treated with the indicated concentrations of METH for 24 hr. The medium was then changed, the cells treated with 100 µM 6-OHDA for 20 min and viability assays performed 24 hr after 6-OHDA removal. Sub-toxic concentrations of METH protected ATP levels (A) and mitochondrial dehydrogenase activity (B), and prevented chromatin condensation of Hoechst stained cells (C). The photomicrographs in Panel (C-I) show control cells lacking any sign of nuclear condensation or chromatin clumping, In panel (C-II) MN9D cells have lifted off the plate after 6-OHDA exposure, presumably due to cell death. Arrows point to dying cells with high chromatin condensation. In panel (C-III) METH pretreated cells were protected against 6-OHDA toxicity (C-III). Data represent means ± SEM (N = 3). *P<0.05 compared to 0 mM METH/100 µM 6-OHDA, #p<0.01compared to 0 mM METH/0 µM 6-OHDA.