Journal of Neuroscience, Vol 15, 5420-5427, Copyright © 1995 by Society for Neuroscience
Synergy between growth factors and transmitters required for catecholamine differentiation in brain neurons
X Du and L Iacovitti
Department of Neurology, Hahnemann University, Philadelphia, Pennsylvania 19102, USA.
The phenotypically plastic neurons of the embryonic mouse striatum were
used to explore mechanisms of catecholamine differentiation in culture. De
novo transcription and translation of the CA biosynthetic enzyme, tyrosine
hydroxylase (TH), was induced in striatal neurons exposed, simultaneously
or sequentially, to the growth factor, acidic fibroblast growth factor
(aFGF) and a catecholamine. Although dopamine was the most potent aFGF
partner (ED50 = 4 microM), a number of substances, including dopamine (D1)
receptor agonists, beta-adrenoceptor agonists, and dopamine uptake
inhibitors also trigger TH induction when accompanied by aFGF. However,
since none of the receptor antagonists nor transport blockers tested could
inhibit dopamine's action, the mechanism remains obscure.
Structure-activity analysis suggests that effective aFGF partners all
contain an amine group separated from a catechol nucleus by two carbons.
Thus, TH expression can be novelly induced by the synergistic interaction
of aFGF, and to a lesser extent basic FGF, and a variety of CA-containing
partner molecules. We speculate that a similar association between growth
factor and transmitter may be required in development for the
differentiation of a CA phenotype in brain neurons.