Developmental change of choline acetyltransferase and acetylcholinesterase in the ciliary and the superior cervical ganglion of the chick

Abstract

The neonatal and early postnatal development of choline acetyltransferase (ChAc) and acetylcholinesterase (AChE) activities, possibly the neurochemical correlates for the formation of cholinergic neurons or synapses, was studied using the ciliary and the superior cervical ganglion of the chicks from the 7th day (stage 31 of Hamburger and Hamilton 10) and the 13th day (stage 39) of incubation, respectively, to the 29th day after hatching. In the ciliary ganglion, where both the pre- and the postganglionic nerves are cholinergic, a sharp increase in the ChAc activity was observed from the 14th day of incubation and reached a maximum on the 29th day after hatching where the value amounted to 450-fold (per pair of ganglia) or 47-fold (per unit weight of protein content) the initial value. On the other hand, the total activity of AChE increased only 7-fold and the specific activity remained practically unchanged. In the superior cervical ganglion, where only the preganglionic nerves are cholinergic, the ChAc and AChE activities began to increase at the 15th day in the embryo, exhibiting an almost similar time course and reached a maximum on the 29th day after hatching. The alteration of both enzyme activities in the ciliary ganglion during development is discussed in connection with the morphological and electrophysiological findings reported to date.