Fig. 6.

The effects of cAMP elevation on survival of spinal motor neurons in culture. Purified spinal motor neurons were cultured in serum-free medium containing the indicated peptide trophic factors or drugs. After 3 d their survival was measured by the MTT assay. All peptides and drugs were used at plateau concentrations as follows: BDNF (10 ng/ml), CNTF (10 ng/ml), HGF (10 ng/ml), GDNF (10 ng/ml), forskolin (10 μm), IBMX (0.1 mm), pertussis toxin (50 ng/ml), CPT-cAMP (125 μm), and CPT-cGMP (125 μm).