Fig. 8. Bryostatin 1, a non-tumour-promoting PKC activator, rescues SGNs from cell death. (A) SGNs were deprived of trophic factor in the presence of increasing concentrations of bryo or 100 nM PMA for 24 hours. Neurons were fixed and the remaining number of viable neurons were counted, as determined in Fig. 2A (n=6; ^**P<0.01; ^***P<0.001). The inset shows a representative micrograph of TUJ1-stained SGNs in a 24 hour culture treated with bryo (10 nM). Bryo treatment strongly enhanced neurite outgrowth, in comparison with the control condition in Fig. 5B. Bar, 80 µm. (B) Representative photomicrographs of PKCßI membrane redistribution in SGNs upon 30 minute bryo exposure. SGNs were cultured for 4 hours in control medium. Next, cultures were treated for 30 minutes with 10 nM bryo. Cells were then fixed and immunostained with PKCßI and TUJ1 antibodies; nuclear staining with TO-PRO-3 was used to appreciate cell density. Before the bryo treatment, PKCßI had a uniform cytoplasmic distribution, as seen in the control condition (Fig. 2H). The experiments were performed in duplicate and repeated on two different occasions, with similar results. Bar, 40 µm. (C) SGNs were treated with 100 nM PMA or 10 nM bryo in the presence or absence of 1 µM GF109203X. After 24 hours, cells were fixed and neuronal viability was examined, as described in Fig. 2A (n=6; ^***P<0.001).