Growth factors effects on the expression of morphological and biochemical properties of avian embryonic sympathetic cells. Emphasis on NGF.

Growth factors are known to be important agents in the differentiation and modulation of neuronal phenotypes. We have analyzed the effect of several growth factors on the modulation of morphological and biochemical properties of avian embryonic sympathetic neurons. The growth factors studied include: 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-beta1). Morphological properties were analyzed by immunocytochemistry to neurofilament proteins and visualization of fibers after glyoxylic acid-induced fluorescence. Biochemical modulation was determined by radioimmunoanalysis for the peptides enkephalin (ENK), somatostatin (SS) and neuropeptide Y (NPY) and by HPLC-electrochemistry quantification of catecholamines. Similar to previous results using chromaffin cell cultures [R. Ramírez-Ordóñez, J.E. García-Arrarás, Peptidergic, catecholaminergic and morphological properties of avian chromaffin cells are modulated distinctively by growth factors, Dev. Brain Res., 87 (1995) 160-171], we found a dissociation in the modulation of biochemical and morphological properties, however, the effect of specific factors differed between the chromaffin and sympathetic cultures. We have focused on NGF to analyze its effect on the sympathetic peptide phenotypes and its lack of an effect on the chromaffin cell peptide phenotypes. The results presented here, establish interesting differences between chromaffin cells and sympathetic neurons that are of importance to studies of cell lineage and differentiation.