Peptidergic, catecholaminergic and morphological properties of avian chromaffin cells are modulated distinctively by growth factors.

Most neurons and endocrine cells are known to co-express a 'classical neurotransmitter' with one or more neuropeptides. Although their expression has been shown to be modulated by differentiation factors, it is not known if particular combinations of neurotransmitter/neuropeptide(s) are co-regulated. We have analyzed the effect of nerve growth factor (NGF), neurotrophin-3 (NT-3), brain derived neurotrophic factor (BDNF), ciliary neurotrophic factor (CNTF), basic fibroblast growth factor (bFGF) and transforming growth factor beta 1 (TGF-beta 1) on the modulation of neuroactive substances co-expressed by avian chromaffin cells. The content of the neuropeptides neuropeptide Y (NPY), enkephalin (ENK) and somatostatin (SS) was measured by radioimmunoanalysis, and the content of the catecholamines norepinephrine (NE) and epinephrine (E) by high pressure liquid chromatography-electrochemistry (HPLC-EC). In addition, the morphological differentiation of chromaffin cells in response to the growth factors was assessed. All of the studied factors had distinct effects on the chromaffin content of neuropeptides and catecholamines. Our results show that the modulation of CAs and neuropeptides, and among the neuropeptides themselves is completely dissociated. Moreover, the cellular responses to the different growth factors show that neurochemical properties are modulated independently of morphological ones.