N-Methyl-N-Nitrosourea-Induced Photoreceptor Degeneration Is Inhibited by Nicotinamide via the Blockade of Upstream Events before the Phosphorylation of Signalling Proteins
Effect of NAM on cell death related signalling proteins. Representative western blots of JNK (a), p38 (B), PARP (c), and AIF (d) are indicated in each densitometry analysis graph. Increased phosphorylated forms of JNK and p38 were observed in retinas 1 and 3 days and 1 day after MNU injection, respectively. The depletion of full-length PARP was observed in MNU-injected retinas. The expression level of AIF was decreased after MNU injection. Data are shown as mean ± standard deviation (n = 4, ,, and : p < 0.05, 0.01, and 0.001, Tukey’s multiple comparison test). AIF: apoptosis-inducing factor; JNK: c-Jun N-terminal kinase; MNU: N-methyl-N-nitrosourea; NAM: nicotinamide; PARP: poly(ADP-ribose) polymerase; and p38: p38 mitogen-activated protein kinase.