Differential effects of cyclic AMP and cholera toxin on nerve growth factor-induced neurite outgrowth from adrenal medullary chromaffin and pheochromocytoma cells.

The extension of neurites from adrenal medullary chromaffin cells and PC 12 cells upon addition of nerve growth factor (NGF) has been proposed to be mediated by cyclic AMP. It is shown here that substances increasing intracellular cyclic AMP levels have a reverse effect on NGF-induced neurite outgrowth of these two related cell types. Hence, cyclic AMP is not generally involved in neurite outgrowth from NGF responsive cells. Furthermore, it is concluded that PC 12 cells cannot always be considered as a suitable model for adrenal medullary chromaffin cells.