Nucleoside Phosphatase and Cholinesterase Activities in Dorsal Root Ganglia and Peripheral Nerve

Abstract

In dorsal root ganglia and peripheral nerve of the rat and other species, nucleoside phosphatase and unspecific cholinesterase reaction products are found in the plasma membranes and spaces between them at two sites: (1) Schwann cell-axon interfaces and mesaxons of unmyelinated fibers, and (2) sheath cell-perikaryon interfaces and interfaces between adjacent sheath cells. Acetylcholinesterase reaction product is found in the perikaryon (within the endoplasmic reticulum) and the axon (axoplasmic surface). Nucleoside phosphatase reaction product is also found in the numerous vacuoles at the surface of perineurium cells, ganglion sheath cells, and cells surrounding some ganglion blood vessels. Nucleoside phosphatase activities in the sections fail to respond, in the manner described for "transport ATPase," to diisopropylphosphofluoridate, sodium and potassium ions, and ouabain. Nucleoside diphosphates are hydrolyzed more slowly than triphosphates in unmyelinated fibers, and are not hydrolyzed at the perikaryon surface. Nucleoside monophosphates are either not hydrolyzed or hydrolyzed very slowly. In contrast to these localizations, which are believed to demonstrate sites of enzyme activity, it is considered likely that diffusion artifacts account for the nucleoside phosphatase reaction product frequently found along the outer surfaces of myelinated fibers and within vacuoles at the Schwann cell surfaces of these fibers. The diffuse reaction product seen in basement membranes of ganglion and nerve may also be artifact.

Enzyme histochemistry of cutaneous sensory nerve formations

“…The fine structural localization of nucleoside diphosphatase (NDPase) activity was first demonstrated in the endoplasmic reticulum (ER) and the Golgi apparatus by Novikoff et al (1966). They used a modification of the WachsteinMeisel medium with inosine diphosphate or thiamine pyrophosphate as substrates.…”

Atpase Activity in the Ciliary Rootlet of Human Retinal Rods

“…The reaction products resulting from incubation in Wachstein-Meisel's medium with adenosine triphosphate as a substrate are observed at the ciliary rootlet in correspondence with its cross-striation. It may be assumed that the deposition of reaction products directly indicates the localization of a certain enzyme, since the various possibilities of deposition of diffusion artifacts (Novikoff et al 1966) may be excluded. The enzyme, the activity of which is demonstrated, might be ATPase in the specific sense, but the alternative explanation remains that the deposit of lead phosphate may not be a direct product of ATPase reaction but may be caused by some further reactions originating from the addition of adenosine triphosphate.…”

Cholinergic signaling in myelination

“…At the ultrastructural level, AChE staining is localized to axonal membrane of myelinated and unmyelinated sciatic nerve fibers (Schlaepfer and Torack, ). AChE activity at nodes of Ranvier was detected in myelinated frog nerve (Brzin and Dettbarn, ), axons of dorsal root ganglia and peripheral nerve (Novikoff et al, ), sciatic nerve (Schlaepfer and Torack, ), myelinating Schwann cells (Bogusch, ), and Schwann cells and axon of the squid giant nerve fiber (Villegas and Villegas, ). Pharmacological evidence for the chemical theory of action potentials was that AChE inhibitors, such as diisopropyl fluorophosphate (DFP), were found to block action potential generation in squid giant nerve (Bullock, ).…”