Serum vulnerability and time-dependent stabilization of neurites induced by nerve growth factor in PC12...

Cultures of PC12 pheochromocytoma cells were established on a polyornithine substratum in medium supplemented with the chemically defined N1 mixture in the presence or absence of Nerve Growth Factor (NGF). Normal cell proliferation in the absence of NGF was equally competent when fetal calf serum (FCS) was replaced with N1-supplemented medium. The differentiation of PC12 cells, which occurs upon NGF treatment, ultimately results in cell death without the addition of 0.1% FCS to the N1-supplemented medium. The combination of N1, 0.1% FCS, and NGF permits the PC12 cells to develop a neuritic outgrowth much earlier than when higher (1-10%) FCS levels are used. Neurite retraction is caused in a dose-dependent manner by a delayed presentation of FCS. Within 2 days of serum presentation, however, neurites regrow to achieve that percentage of neurite-bearing cells which is seen without a serum challenge. Moreover, the retraction response becomes less pronounced with time over the 8-day culture period for any given serum concentration. Among the N1 ingredients, only insulin and transferrin are needed by PC12 cells for survival whether in the dividing state or not. Neurite growth was not dependent on any of the N1 components.