CHOLINESTERASES IN DEGENERATING AND REGENERATING PERIPHERAL NERVES

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Abstract
The guinea pig sciatic nerve contains relatively arge amts. of the specific or true cholinesterase (ChE) and small amts. of the non-specific or pseudo-ChE. Extracts of unoperated nerve hydrolyze mecholyl (specific substrate for true ChE) nearly 60% as readily as acetylcholine (ACh) and benzoylcholine (substrate for pseudo-ChE) only 20% as rapidly as ACh. Sectioning the nerve leads, within the first few days, to a 60% loss of true ChE from the degenerating tibial and peroneal nerves. Further loss of enzyme fails to occur even with a complete disintegration of axis cylinders. Pseudo-ChE activity is unaffected by the operation while total ACh hydrolyzing capacity, dependent on the 2 enzymes, decreases 30%. Neuromas, developing on the proximal ends of the sectioned sciatic nerves, contain great numbers of fine regenerating axons, and their ACh hydrolyzing power is 3 times as great as that in the controls. The rise is due almost entirely, if not totally, to increased true ChE content. It is concluded that nearly 2/3 of the true ChE in the control nerves is secreted by the axis cylinders, but that more than 1/3 is produced by some other element or elements, perhaps Schwann''s sheath cells. Pseudo-ChE is probably completely resident in the connective tissue of the sheaths.