Figure 1. VPA induces neuronal cell death; inhibited by calpain, JNK and necroptosis inhibitors.
(A) PC12 cells neuronally differentiated as described in MM were treated with VPA (0.05, 0.2, 0.5, 1, 5mM), and assayed for cell death by ethidium homodimer staining 3 and 5 days later. Dead cells (red staining) were counted in 4 quadrants and the % dead cells was calculated and normalized to untreated cells. The results are expressed as % death cells ± SE. (B) PC12, PC70, and PC47 cells were differentiated as in (A). They were treated with VPA (1mM) and assayed for cell death by trypan blue exclusion 1, 2, 3, and 5 days later. Dead cells (blue staining) were counted in 4 quadrants and the % dead cells was calculated and normalized to untreated cells. The results are expressed as % trypan blue+ cells ± SE. (C) Primary rat cortex neurons were mock or VPA (1mM)-treated and assayed for cell death by trypan blue staining 3 days post-treatment. Dead and live cells were counted as in (B) and the % dead cells was calculated and normalized to untreated cells. (D) PC12 cells cultured and differentiated as in (A) were treated with VPA (1mM) alone or with z-VAD-fmk (50 µM), PD150606 (PD, 100 µM), SP600125 (SP, 100 µM) or Nec-1 (Nec, 50 µM) and assayed for cell death by trypan blue exclusion at 1,2,3,and 5 days post-treatment. Dead and live cells were counted as in (B) and the % dead cells was calculated and normalized to untreated cells. The results are expressed as % inhibition ± SE calculated from the formula: 100-((% death with inhibitors/% death without inhibitors) ×100). Maximal inhibitory levels were reached on day 3 post-treatment as determined by one-way ANOVA. (E) Primary rat cortex neuronal cells were treated with VPA (1mM) alone or in the presence of z-VAD-fmk (50 µM) or PD150606 (PD, 100 µM) and assayed for cell death by trypan blue 3 days post-treatment. Dead and live cells were counted as in (B) and the % dead cells was calculated and normalized to untreated cells. The results are expressed as % inhibition ± SE, calculated as in (D). (*P<0.01; **P<0.001)