Identification of the probable site of synthesis of butyrylcholinesterase in the superior cervical and ciliary ganglia of the cat.

The source of butyrylcholinesterase (acylcholine acylhydrolase, EC 3.1.1.8) in the ganglion cells of the cat superior cervical and ciliary ganglia has been elusive, inasmuch as the enzyme is present in high concentrations in the neuropil, where it is confined largely to the dendritic and perikaryonal plasma membranes, but appears to be absent from the perikarya. In the present study, ganglionic butyrylcholinesterase was near-totally inactivated by the injection of tetramonoisopropyl pyyrophosphoramide (6.0 mumol/kg of body weight) intravenously. During the ensuing 72 hr, the regenerating enzyme became detectable by the copper thiocholine histochemical method in the somata of essentially all ganglion cells and in the neuropil. Results were similar in preganglionically denervated superior cervical ganglia and in normal ciliary ganglia. These findings suggest (i) that butyrylcholinesterase indeed is synthesized in the ganglion cell perikarya (presumably, the rough endoplasmic reticulum) and transported extremely rapidly to more peripheral cellular sites and (ii) that the synthesis is largely independent of control by any neurotrophic factor provided by the preganglionic axonal terminals. Similar studies were conducted in the rat. In this species, in contrast to the cat, the somata of essentially all ganglion cells of the superior cervical ganglion contain various but at least moderate concentrations of acetylcholinesterase (acetylcholine acetylhydrolase, EC 3.1.1.7) and propionylcholinesterase (acylcholine acylhydrolase, EC 3.1.1.8). After injection of tetramonoisopropyl pyrophosphoramide, propionylcholinesterase reappeared in the ganglion cell somata before its accumulation in the neuropil, as would be expected.