[Effect of retinoic acid, dibutyryl cyclic AMP, and nerve growth factor on NADPH-specific dihydropteridine reductase of teratoma 402AX cells in culture].

Effects of retinoic acid (RA), dibutyryl cyclic AMP (dBcAMP), and nerve growth factor (NGF) on the morphology and the NADPH-specific dihydropteridine reductase (NADPH-DPR) activity of teratoma 402AX cells were studied. The population of cells with flattened shape was increased by the treatment with RA+dBcAMP, or with RA+dBcAMP+NGF, while the treatment with NGF alone had almost no effect on the morphology. The NADPH-DPR activity was increased by the treatment of the cells with RA+dBcAMP+NGF and with RA+dBcAMP by about 2.2-fold and 1.8-fold, respectively, of that detected in the control (untreated) cells. Also in this case, NGF alone failed to increase the enzyme activity. On the other hand, no change in NADH-specific dihydropteridine reductase (NADH-DP) activity was detected by the treatment of the cells with either RA+dBcAMP, RA+dBcAMP+NGF, or NAF alone. These results suggest that the cells acquire responsiveness to NGF by the treatment with RA and dBcAMP and that NADPH-DPR may play some regulatory role in tetrahydrobiopterin regeneration from its quinonoid-dihydro form.