Time course of proteolytic enzyme alterations in the motor end-plates after stimulation

doi:10.1016/S0065-1281(76)80006-2

Acta Histochemica

Volume 57, Issue 1, 1976, Pages 44-48, IN3-IN4

https://doi.org/10.1016/S0065-1281(76)80006-2 Get rights and content

Summary

Authors studied the proteolytic enzyme activity of motor end plates in the diaphragms and M. flexor digitorum brevis of rats after administration of Cholinesterase inhibitors and after supramaximal electric stimulation, using the colour film digestion technique. Enhanced enzyme activity characterizing stimulated motor end plates persisted up to 12 h after stimulation. No proteolytic activity could be shown any more 24 h after stimulation, indicating restoration of the resting state. The role of metabolites (oligopeptides and amino-acids) released by the function-dependent axoterminal proteolysis is discussed in relation to neurochemical transmission processes.

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Cited by (7)

Matrix metalloproteinase-7 modulates synaptic vesicle recycling and induces atrophy of neuronal synapses
2007, Neuroscience
Citation Excerpt :
A reduction in the abundance of synaptic proteins including synaptophysin, a reduction in the number of vesicles, and a reduction in active zone size are hallmarks of synaptic disassembly (Eaton and Davis, 2003; Goda and Davis, 2003). Neuronal proteases, including MMPs, have been implicated in the elimination or structural modulation of neuromuscular junctions during development (Poberai and Savay, 1976; O’Brien et al., 1978; Connold et al., 1986; Liu et al., 1994a,b; VanSaun et al., 2003). Similar proteolytic mechanisms may apply to central synapses; although the identity of participating proteases and inherent mechanisms remains unknown.
Matrix metalloproteinase-7 (MMP-7) belongs to a family of zinc dependent endopeptidases that are expressed in a variety of tissues including the brain. MMPs are known to be potent mediators of pericellular proteolysis and likely mediators of dynamic remodelling of neuronal connections. While an association between proteases and the neuronal synapse is emerging, a full understanding of this relationship is lacking. Here, we show that MMP-7 alters the structure and function of presynaptic terminals without affecting neuronal survival. Bath application of recombinant MMP-7 to cultured rat neurons induced long-lasting inhibition of vesicular recycling as measured by synaptotagmin 1 antibody uptake assays and FM4-64 optical imaging. MMP-7 application resulted in reduced abundance of vesicular and active zone proteins locally within synaptic terminals although their general levels remained unaltered. Finally, chronic application of the protease resulted in synaptic atrophy, including smaller terminals and fewer synaptic vesicles, as determined by electron microscopy. Together these results suggest that MMP-7 is a potent modulator of synaptic vesicle recycling and synaptic ultrastructure and that elevated levels of the enzyme, as may occur with brain inflammation, may adversely influence neurotransmission.
The effect of acetylcholine on the function and structure of the developing mammalian neuromuscular junction
1980, Neuroscience
Isolated soleus muscles from rats aged 9–12 days were exposed to acetylcholine for 2 h in normal Krebs solution. This treatment caused changes in the ultrastructural appearance of the neuro-muscular junction and a significant reduction of axon profiles per endplate. Nevertheless, most neuro-muscular junctions remained functional, since the ratio of the indirectly to directly elicited contraction was not reduced.
If muscles were exposed to acetylcholine in Krebs solutions containing 12m M Ca²⁺ instead of the normal 1.9 m M, the ultrastructural changes produced by acetylcholine were more severe, and the number of axon terminals per endplate was further reduced so that many endplates became completely denervated. This was also reflected in the impaired function of the nerve-muscle preparation; the ratio of the indirectly to directly elicited contraction decreased and about 40% of the muscles fibres became functionally denervated. Addition of curare to the incubating medium prevented the functional deterioration of the preparation.
Addition of the protease inhibitors leupeptin and pepstatin protected the nerve terminals from the damaging effects of acetylcholine in Krebs solution containing 12m M Ca²⁺ and the number of axon profiles per endplate remained normal. The functional deterioration was also much reduced when protease inhibitors were included in the incubation medium.
These results suggest that acetylcholine causes the activation and release of proteolytic enzymes in developing muscles. The response is mediated by calcium and may have a role in the removal of superfluous nerve-muscle contacts during development.
Development of the vertebrate neuromuscular junction
2009, The Sticky Synapse: Cell Adhesion Molecules and Their Role in Synapse Formation and Maintenance
Developmental regulation of the serpin, protease nexin I, localization during activity-dependent polyneuronal synapse elimination in mouse skeletal muscle
1998, Journal of Comparative Neurology
Plasminogen activators and inhibitors in the neuromuscular system: III. The serpin protease nexin I is synthesized by muscle and localized at neuromuscular synapses
1991, Journal of Cellular Physiology
A LIGHT AND ELECTRON MICROSCOPIC HISTOCHEMICAL STUDY ON THE MECHANISM OF DFP‐INDUCED ACUTE AND SUBACUTE MYOPATHY
1981, Neuropathology and Applied Neurobiology

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¹: Address: Prof. Dr. Gyula Sávay, Department of Anatomy, University Medical School Szeged, Kossuth L. sgt. 40, 6701 Szeged, Hungary.

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Time course of proteolytic enzyme alterations in the motor end-plates after stimulation

Summary

Histochemistry of myelin. III. Peripheral nerve cathepsin

J. Histochem. Cytochem.

Synaptochemistry. Outlines and Scope of a Discipline

J. Neural. Transmiss. Suppl.

Function-dependent alterations in the distribution of synaptic vesicles

Acta biol. Acad. Sci. Hung.

Enhanced interpretation of tissue protease activity by use of photographic color film as a substrate

Stain Tech.

Survival of the perfused cat's brain in the absence of glucose

Nature (London)

The incorporation of 14C derived from glucose into the proteins of the brain cortex, at rest and during activity

J. Neurochem.

Protein metabolism in the nerve cells during growth and function

Acta physiol. Scan.

The effect of nerve stimulation and hemicholinium on synaptic vesicles at the mammalian neuromuscular junction

J. Physiol. (London)

The incorporation of ¹⁴C derived from glucose into the proteins of the brain cortex, at rest and during activity