Development of adrenergic neurons in uiuo: inhibition by ganglionic blockade

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Abstract
The Normal biochemical maturation of postsynaptic adrenergic neurons in mouse and rat superior cervical ganglion depends upon an intact preganglionic innervation (Black, Hendry and Iversen, 1971a, 1972; Thoenen, Saner and Keitler, 1972). In recent studies tyrosine hydroxylase, the rate‐limiting enzyme in norepinephrine biosynthesis (Levitt, Spector, Sjoerdsma and Udenfriend, 1965), with localization to adrenergic neurons in the ganglion (Black, Hendry and Iversen, 1971b), was used to monitor maturation of these cells. The developmental increase in tyrosine hydroxylase activity occurred simultaneously with the appearance of ganglionic synapses and was prevented by transection of the preganglionic nerve trunk (Black, Hendry and Iversen, 1971a). These observations suggest that presynaptic cholinergic nerve terminals regulate the biochemical development of postsynaptic neurons in the superior cervical ganglion. The mechanism(s) by which presynaptic cholinergic terminals regulate postsynaptic development has not been elucidated. Such trans‐synaptic regulation may be dependent on normal impulse transmission and/or may involve other unidentified, trophic factors. The results presented in the present communication suggest that normal development of ganglionic tyrosine hydroxylase activity is dependent on depolarization of postsynaptic adrenergic neurons.