Phenotype plasticity and immunocytochemical evidence for ChAT and DβH co-localization in fetal pig superior cervical ganglion cells

The early expression of the cholinergic phenotype in sympathetic neurons was already studied in superior cervical ganglion cells derived from rat, quail and chicken embryo. In the present work, we set up a neuron culture derived from the superior cervical ganglia of fetal pigs. The yield is 1000 times of that of a neonatal rat [17], 100 times of a 10- to 13-day-old chick embryo [26] and 20 times of a 10-day-old quail embryo [3]. This high yield will greatly facilitate further biochemical studies concerning neuronal differentiation. Using these cells as a model, the phenotype plasticity was studied by both biochemical and immunocytochemical methods in normal physiological medium, in a high KCl (30 mM) medium and in a splenocyte co-culture. The phenotype shift occurs in the normal physiological medium and in the splenocyte co-culture, but not in the high KCl medium. Taking into account the species difference, the fetal pig superior cervical ganglion neurons behave in a comparable manner as reported in earlier studies for other animal models. Moreover, for the first time, using immunocytochemical methods, direct evidence for a co-localization of choline-acetyl-transferase and dopamine-β-hydroxylase in mammalian fetal sympathetic neurons, at least during a certain culture period, is given.