Fig. 1.
Synergistic action of RA and BMP2 on the induction of GDNF responsiveness of SCG neurons for their survival. Neurons dissociated from E17 rat SCG were treated with 10−7m RA and/or 10 ng/ml BMP2 in the absence or presence of 40 ng/ml GDNF for 4 d before numbers of surviving neurons were counted (A) and photomicrographs were taken (B). The number of viable neurons (cells with round and phase-bright soma and neurites) within 2 × 3 mm rectangles in each well was counted and expressed as percentage of the number of neurons surviving in the presence of 40 ng/ml NGF at 24 hr after plating. Each column represents the mean and SD (n = 4–6). *p < 0.0001 compared between GDNF plus RA and GDNF alone; #p < 0.0001 compared between GDNF plus RA plus BMP2 and GDNF plus RA (ANOVA, with Boneferroni correction for multiple comparison). Note that BMP2, which had no effect by itself, promoted the action of RA to enhance the GDNF-dependent survival. Scale bar (in B), 100 μm.