Fig. 3

Caspase-3 cleavage and activation of ERK1/2 MAP kinase in cortical neurons exposed to ac-PGP. a Immunocytochemistry of neurons exposed to vehicle or 10 nM ac-PGP for 24 h. Cleaved caspase-3 was present at low levels in vehicle-treated cells and was significantly elevated in ac-PGP-treated cells. Stages of apoptosis are indicated I–III. I appearance of cleaved caspase-3 in the nucleus, II nuclear condensation, III nuclear fragmentation. b Western blot of cleaved caspase-3 in neuronal cell extracts after exposure to 0, 0.01, 0.1, 1, 10, or 100 nM ac-PGP for 24 h, lanes 1–6, respectively. c Quantitation of Western blot data shown in b. A statistically significant difference in cleaved caspase-3 levels between vehicle and all doses of ac-PGP was observed (*p < 0.0001), while 10 nM ac-PGP produced a significantly higher level of caspase-3 cleavage than 0.01 and 0.1 nM ac-PGP (^# p < 0.001 to p < 0.05). Cleaved caspase-3 levels were normalized to full-length caspase-3. GAPDH, cytoplasmic marker glyceraldehyde 3-phosphate dehydrogenase. d Western blot of phospho-ERK1/2 MAP kinase after exposure to 10 nM ac-PGP for the times indicated in e. Phospho-ERK1/2 levels were normalized to total ERK1/2. A statistically significant difference in ERK1/2 phosphorylation was observed between neurons treated with vehicle and ac-PGP for 5, 15, 30, and 60 min (*p < 0.005 to p < 0.05). ERK1/2 phosphorylation was significantly decreased at 180 min compared to 30 min (^# p < 0.05)