ABSTRACT
Of the growth factors that have been shown to affect adrenal chromaffin cells and their tumor derivatives, particularly pheochromocytoma 12 cells, nerve growth factor is by far the best characterized. In dissociation experiments, chromaffin cells from 10-day-old rats exhibited two classes of nerve growth factor receptors, similar to those found in other nerve growth factor-responsive cells. The effect of nerve growth factor did not depend on protein synthesis, but it was blocked by methyltransferase inhibitors. Shaw and Letourneau examined the developmental effects of nerve growth factor on embryonic chick adrenal cells in culture. Their findings suggest that a growth factor with physiologic and antigenic similarities to nerve growth factor is produced by cultured embryonic chick adrenal cells but that this growth factor affects different subpopulations of chromaffin cells in different ways. Nerve growth factor induced tyrosine hydroxylase but not phenylethanolamine N-methyltransferase activity, and ciliary neuronotrophic factor did not change the activity of either enzyme.
