Fig. 2. Transcriptional dependence of axonal growth. (A) Mean axonal outgrowth distances from freshly dissected and in vitro conditioned PN-DRG in collagen gels after 3 days, in response to BDNF in the presence or absence of ActD. Conditioned PN-DRG show enhancement of both spontaneous and BNDF-induced axonal growth. ActD inhibits BDNF-induced axonal outgrowth from freshly dissected preparations but not from conditioned preparations. (B) Effects of prior incubation with -AM on subsequent BDNF-induced axonal outgrowth in the presence or absence of ActD. Preparations were incubated (free-floating) for 4 days with -AM present on day 1, day 4 or not at all, prior to culturing in collagen gels for 3 days with or without BDNF. Incubation with -AM on day 1 strongly inhibits subsequent BDNF-induced axonal outgrowth in collagen gels, but incubation with -AM on day 4 does not.