Sprouting of frog motor nerve terminals after long-term paralysis by botulinum type A toxin

doi:10.1016/0304-3940(89)90045-1

Neuroscience Letters

Volume 96, Issue 2, 16 January 1989, Pages 127-132

https://doi.org/10.1016/0304-3940(89)90045-1 Get rights and content

Abstract

A single sublethal injection of botulinum type A toxin (BoTx-A) to winter frogs induced a general and complete paralysis of skeletal muscles, which lasted several months. Quantitative analysis of 483 endplates from 8 BoTx-A poisoned muscles and 495 endplates from 8 control muscles revealed a higher and significant incidence of terminal and ultraterminal sprouts in poisoned junctions when taking into account the normal remodelling of motor innervation. We conclude that prolonged neuromuscular blockade by BoTx-A results in the extension of the nerve terminal arborization.

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Cited by (19)

Clostridial neurotoxins: From the cellular and molecular mode of action to their therapeutic use
2015, The Comprehensive Sourcebook of Bacterial Protein Toxins
Botulinum (BoNT) and tetanus (TeNT) neurotoxins are potent toxins responsible for flaccid and spastic paralysis, respectively. BoNTs are divided into types and subtypes according to their immunological properties and amino acid sequence variations, whereas only one type of TeNT has been characterized. BoNTs associate with nontoxic proteins to form large complexes that are resistant to acidic pH and protease degradation, unlike TeNT, which is produced as a unique protein. BoNTs and TeNT enter target neuronal cells by interacting with specific cell surface receptors. BoNTs proteolytically cleave soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins (SNAP-25, VAMP, or syntaxin) mainly at the cholinergic neuromuscular junctions impairing the evoked release of acetylcholine, whereas TeNT inhibits the neuroexocytosis in central inhibitory interneurons by cleavage of VAMP. BoNT-mediated muscle paralysis induces neuronal sprouting, which after various time periods, leads to a recovery of neurotransmission. BoNT/A, which has a long duration of activity, is used in numerous medical applications.
Chapter 2 Reliability of neuromuscular transmission and how it is maintained
2008, Handbook of Clinical Neurology
Citation Excerpt :
More direct evidence for such a phenomenon is presented below. Anatomical studies in animals and humans suggest that the structure of NMJs changes with age (Fig. 2.30) (Barker and Ip, 1966; Tuffery, 1971; Bennett and Stenbuck, 1980; Bennett and Davis, 1982; Arizono et al., 1984; Oda, 1984; Cardasis and LaFontaine, 1987; Diaz et al., 1989; Wokke et al., 1990; Rich et al., 1998). In most cases, these changes involve increased local complexity of axonal branching within individual NMJs (Oda, 1984; Andonian and Fahim, 1989; Prakash and Sieck, 1998), which may (Waerhaug, 1992), or may not (Fahim and Robbins, 1982; Fahim et al., 1983), be associated with an overall change in the total area of the NMJ.
An important function of all nervous systems is to control muscle contraction so that movements of the body are appropriate to promote survival. In most species, specialized motor neurons convey the signals that represent the neural commands for contraction from the central nervous system to the muscle fibers. This chapter describes the process of neuromuscular transmission. The chapter emphasizes on how the properties of the neuro muscular junctions (NMJs) ensure the reliability of transmission in a wide range of biological circumstances and how changes to those properties may lead to impaired transmission in disease. The main features of neuromuscular transmission, in addition to the essential presynaptic and postsynaptic aspects of neuromuscular transmission, are also described in the chapter. The chapter describes the measurement of safety factors and some of the modulating influences on the safety factor during normal use. The chapter accounts for several important aspects of the “biology” and adaptive plasticity of the NMJ, triggered by trauma or intoxication that promotes maintenance of the effective neural control of muscle. The principles of the functional organization of the NMJ can inform efforts to understand impaired neuromuscular transmission in disease. This account of neuromuscular transmission and its reliability is based on studies of a small number of laboratory species. The emphasis is on mammals, including humans. While neuromuscular transmission in different species has much in common, there are also many important differences. It is therefore always necessary to use caution when trying to interpret findings in one species on the basis of knowledge of another. The ability of the NMJ to recover from a wide variety of mechanical and chemical assaults indicates the evolutionary importance of effective and reliable neuromuscular transmission.
Gene expression of nAChR, SNAP-25 and GAP-43 in skeletal muscles following botulinum toxin A injection: A study in rats
2005, Journal of Orthopaedic Research
Purpose: Botulinum toxin A (BoNT-A) is used to manage spasticity in cerebral palsy. BoNT-A cleaves SNAP-25 protein, blocking acetylcholine release and weakening the muscle. Nicotinic acetylcholine receptors (nAChR) including alpha, beta, delta, gamma, and epsilon subunits, and GAP-43 protein are associated with functional recovery of neuromuscular junctions (NMJ) following BoNT-A. To better understand the mechanism behind this functional recovery, this study attempted to (1) document changes in NMJ morphometry following BoNT-A, and (2) determine the gene expression of nAChR subunits, SNAP-25, and GAP-43 protein.
Methods: In this rat study (46 rats), 6 units/kg body weight of BoNT-A was injected into the gastrocnimus. NMJ morphometry and the time course of gene expression of nAChR subunits, SNAP-25, and GAP-43 were evaluated up to 1 year post-injection.
Results: NMJ morphometry: gutter depth was reduced vs. the control side at two months, and normalizing by 6 months following BoNT. nAChR alpha mRNA and gamma mRNA increased by 3 days, peaked at 7 days and returned to control levels; delta mRNA peaked at 3 days. Epsilon mRNA peaked by 7 days. SNAP-25 mRNA increased from 60 to 90 days, returning to control levels by 6 months. GAP-43 mRNA was unchanged.
Conclusions: Specific nAChR subunit mRNA expression up-regulates and then returns to normal within two weeks, preceding changes in NMJ morphometry. Although GAP-43 participates in nerve sprouting, no increase of GAP-43 mRNA occurred following BoNT-A. Delayed up-regulation of SNAP-25 mRNA might be associated with muscle functional recovery.
Persistence of botulinum neurotoxin action in cultured spinal cord cells
1999, FEBS Letters
Primary dissociated fetal mouse spinal cord cultures were used to study the mechanisms underlying the differences in persistence of botulinum neurotoxin A (BoNT/A) and botulinum neurotoxin/E (BoNT/E) activities. Spinal cord cultures were exposed to BoNT/A (0.4 pM) for 2–3 days, which converted approximately half of the SNAP-25 to an altered form lacking the final nine C-terminal residues. The distribution of toxin-damaged to control SNAP-25 remained relatively unchanged for up to 80 days thereafter. Application of a high concentration of BoNT/E (250 pM) either 25 or 60 days following initial intoxication with BoNT/A converted both normal and BoNT/A-truncated SNAP-25 into a single population lacking the final 26 C-terminal residues. Excess BoNT/E was removed by washout, and recovery of intact SNAP-25 was monitored by Western blot analysis. The BoNT/E-truncated species gradually diminished during the ensuing 18 days, accompanied by the reappearance of both normal and BoNT/A-truncated SNAP-25. Return of BoNT/A-truncated SNAP-25 was observed in spite of the absence of BoNT/A in the culture medium during all but the first 3 days of exposure. These results indicate that proteolytic activity associated with the BoNT/A light chain persists inside cells for >11 weeks, while recovery from BoNT/E is complete in <3 weeks. This longer duration of enzymatic activity appears to account for the persistence of serotype A action.
Cellular and Molecular Mode of Action of Botulinum and Tetanus Neurotoxins
1997, Advances in Organ Biology
Botulinum (BoNT, serotypes A-G) and tetanus (TeNT) neurotoxins are di-chain bacterial proteins. They are also known under the generic term of clostridial neurotoxins. They are the causative agents of two severe neuroparalytic diseases, namely boutlism and tetanus. Boutlism is characterized by a near irreversible and selective inhibition of quantal acetylcholine release at the skeletal neuromuscular junctions. Tetanus is the result of a blockade of inhibitory synapses in the central nervous system. The cholinergic specificity of BoNTs allows to use these potent neurotoxins as pharmcological agents to induce a chemical denervation of muscle. The effect is exploited to better understand the trophic interrlations that exist between motor nerve terminals and muscle fibres and, in the clinic, to treat a number of disabling abnormal postures or movements such as dystonia and strabismus. The cellular and molecular modes of action of clostridial neurotoxins have been elucidated. After a binding step at specific membrance acceptors located only on nerve terminals, BoNTs and TeNT are internalized into neurons. Then, their intercellularly active moiety is translocated from the endosomal compartment to the cytosol. The intracellular inhibition of neurotransmitter release produced by BoNTs or TeNT involves their light chains and consists in the selective proteolysis of one among three synaptic proteins viz VAMP/synaptobrevin, syntaxin or SNAP-25. These different actions correlate with differneces in the quantal alternation of acetycholine release which characterize certains toxin serotypes. Thus, attempts at deciphering the multiple mode of action of BoNTs and TeNT gave insights into the molecular physiology of the synapses.
Botulinum-A toxin in the treatment of craniocervical muscle spasms: Short- and long-term, local and systemic effects
1996, Survey of Ophthalmology
Botulinum toxin has become the initial treatment of choice for the management of essential blepharospasm, hemifacial spasm and other craniocervical dystonias. Numerous studies have confirmed a 90% to 95% response rate. Although a number of common side effects have been reported, the occurrence and incidence of rare local complications remains poorly understood. More importantly, the acute and chronic distant effects of botulinum toxin have not been clearly elucidated. A better understanding of such effects is essential if clinicians are to appropriately advise patients on the use of this therapeutic modality. This article is based on the Duke University experience in the management of over 500 patients with craniocervical spasm disorders, combined with a review of the published literature. These disorders include essential blepharospasm, oromandibular dystonia, hemifacial spasm, and torticollis. The incidence of side effects following more than 6000 treatments with botulinum toxin is presented. Pertinent research relating to the causes of these complications is also reviewed. The most common complications of treatment with botulinum toxin are related to acute local effects resulting from chemodenervation. The most important clinical effect in this group is weakening of the levator muscle resulting in ptosis, and the corneal consequences of lagophthalmos. The latter includes exposure keratitis, dry eyes, blurred vision, and hypersecretion epiphora. Less common local effects include facial numbness, diplopia, and ectropion. Some distant effects are being observed with increasing frequency. These include pruritis, dysphagia, nausea, and a flu-like syndrome. Most significant, however, are the rare reports of generalized weakness and the documentation of EMG abnormalities distant to the site of toxin injection. This has been seen with injections for both blepharospasm and torticollis. Until further studies on the long-term distant complications of botulinum toxin are available, it is recommended that patients receive as few life-time doses of toxin as possible, consistent with adequate management of their spasms. The practice of reinjecting patients routinely every three months, or at the first return of mild spasms should be discouraged.

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Sprouting of frog motor nerve terminals after long-term paralysis by botulinum type A toxin

Abstract

Prog. Neurobiol.

Neuroscience

Brain Res.

Prolonged paralysis, caused by the local injection of botulinum toxin, fails to cause motor nerve terminal sprouting in skeletal muscle of the frog

Q. J. Exp. Physiol.

Light and electron microscopic identification of nerve terminal sprouting and retraction in normal adult frog muscle

J. Physiol. (Lond.)

Different quantal responses within single frog neuromuscular junctions

J. Physiol. (Lond.)

Prevention of motor nerve sprouting in botulinum toxin poisoned mouse soleus muscles by direct stimulation of the muscle

J. Physiol. (Lond.)

Motor nerve sprouting

Annu. Rev. Neurosci.

An improved combined cholinesterase stain and silver impregnation method for quantitative analysis of innervation patterns in frog muscle

Stain Technol.