Survival and neuritic growth of sympathoadrenal (chromaffin) precursor cells in vitro

Chromaffin precursor cells from embryonic rat adrenal glands were isolated at 16.3 and 20.3 days of gestation and purified by centrifugation on density gradients. Approximately 50% of the cells of both age groups that had attached to the culture substratum by 12 hr survived during a 4-day culture period in the absence of exogenous trophic factors. Nerve growth factor (NGF) and a C6 glioma-cell-conditioned medium (C6-CM) had no or a very moderate promoting effect on survival. The glucocorticoid dexamethasone (DEX) supported the survival of 70-80% of the cells that otherwise would have died. Spontaneous neuritic growth of the sympathoadrenal precursor cells was significantly more pronounced with cells isolated at embryonic day (E) 16.3 than at E20.3. NGF had a significantly smaller promoting effect on neurite ougrowth at E16.3 than at E20.3. C6-CM induced neurite outgrowth from 25% (E16.3) and 35% (E20.3) of the surviving cells. DEX (10(-6) M) completely abolished spontaneous neuritic growth and partially suppressed C6-CM-mediated fiber outgrowth. These data underscore the importance of glucocorticoids for the maintenance and development of an endocrine morphologic phenotype of sympathoadrenal precursors. They suggest that the cells may be initially driven by growth factors other than NGF into a neuronal direction and that they lack NGF-responsiveness and -dependence during the early stages of their development.