Phenotypic alterations of neuropeptide Y, vasoactive intestinal peptide and choline acetyltransferase in rat cultured chromaffin cells as effected by nerve growth factor and glucocorticoid.

We assessed changes in neuropeptide Y (NPY), vasoactive intestinal peptide (VIP) and choline acetyltransferase (ChAT) immunoreactivities when neonatal rat chromaffin cells were cultured in a medium containing nerve growth factor (NGF), or the synthetic glucocorticoid dexamethasone (DEX), examining whether their expression was correlated with the morphological changes induced by NGF and DEX. All of the chromaffin cells in culture were tyrosine hydroxylase (TH)-immunopositive regardless of whether they extended processes. TH-immunoreactive materials of NGF-treated chromaffin cells were distributed in all the cytoplasmic processes, even at the tips of growth cones. The percentage of NPY-positive chromaffin cells did not change markedly when treated with NGF or DEX throughout the 14 days in culture. The proportion of VIP-positive chromaffin cells increased gradually in the NGF-treated group and that of ChAT-positive cells in the group was similar to VIP. The morphological alterations induced by NGF were not correlated with the changes in proportions of NPY-, VIP- or ChAT-positive chromaffin cells. The percentages of VIP- or ChAT-immunopositive chromaffin cells in the NGF-treated group showed much greater increases than those in the DEX-treated group. These findings suggest that NGF might modulate the phenotypic changes of neuropeptides and amines in rat chromaffin cells.