Head and trunk neural crest in vitro: Autonomic neuron differentiation

Isolated cultures of premigratory neural crest cells were used to study the initial stages of autonomic neuron development. Autonomic neurons are phenotypically characterized on the basis of their neurotransmitter synthetic enzymes, dopamine β-hydroxylase (DBH) and choline acetyltransferase (CAT). DBH converts dopamine to norepinephrine in noradrenergic neurons while CAT synthesizes acetylcholine from choline in cholinergic neurons. Activities of both enzymes were detected in isolated cultures of trunk neural crest and head neural crest. DBH was detected at all culture ages examined (from 1 to 20 days) whereas CAT activity was first detected only after 5 days in vitro. While specific enzyme activity of DBH peaks on Day 6 and specific enzyme activity of CAT peaks on Day 10, absolute activity for both enzymes increases throughout the 20-day culture period. DBH and CAT develop in vitro without any spinal presynaptic input, without typical target tissue interactions (such as blood vascular elements or heart tissue), and without addition of conditioned medium factors.