The MECHANISM OF ACTION OF Β‐BUNGAROTOXIN

Wernicke, Joachim; Vanker, Anthony D.; Howard, Bruce D.

doi:10.1111/j.1471-4159.1975.tb04354.x

Cited by 129 publications

(79 citation statements)

References 43 publications

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“…Weak phospholipase A activity is also shown by the presynaptic neurotoxins, fl-bungarotoxin (Wernicke, Vanker & Howard, 1975), notexin (Halpert & Eaker, 1975) and taipoxin (Fohlman, Eaker, Karlsson & Thesleff, 1976). Although the role of catalytic activity in the neurotoxic action of notexin has been contested (Halpert, Eaker & Karlsson, 1976) it is strongly implicated in the action of G-bungarotoxin (Abe, Limbrick & Miledi, 1976).…”

Section: Discussionmentioning

confidence: 99%

The Mode of Action at the Mouse Neuromuscular Junction of the Phospholipase A‐crotapotin Complex Isolated From Venom of the South American Rattlesnake

Hawgood

Smith

1977

British J Pharmacology

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I Phospholipase A2-crotapotin complex (P-C complex) isolated from the venom of Crotalus durissus terrificus induced an irreversible blockade of neuromuscular transmission when twitch tension was measured in the mouse phrenic nerve-hemidiaphragm preparation in vitro at 370C. 2 A similar concentration of the phospholipase A2 (10 jig/ml) alone did not affect neuromuscular transmission and no priming action was detected on later addition of crotapotin. 3 The rate of neuromuscular blockade induced by P-C complex (15,g/ml) was not altered by raising the frequency of nerve stimulation. Lower temperatures markedly increased the time of onset and reduced the rate of blockade (Qlo (27-37°C) of 4.4) whilst replacement of Ca by Sr in the medium prevented this activity. These latter results suggest that enzymatic activity is important iin the neurotoxicity of the complex. 4 A myotoxic action was shown by 30 gg/ml P-C complex and 30 gg/ml phospholipase A2.S P-C complex (150 jg) was injected into the tail vein of mice and the intoxicated hemidiaphragm preparation removed for intracellular recording at 250 C. 6 In fully intoxicated hemidiaphragms, resting membrane potentials were unaltered and endplate potentials (e.p.ps) varied in average amplitude from zero to less than 3 mV. 7 Miniature endplate potential (m.e.p.p.) frequency was lower at fully poisoned endplates than at controls; the frequency rose during a 50 Hz tetanus but was unaffected by either raising external K or the application ofthe Ca-ionophore A23 187. 8 E.p.ps were recorded in partially intoxicated hemidiaphragms with (+)-tubocurarine (0.5-1.0 gg/ml) added to prevent contraction. Evoked release was abnormal as 50 Hz tetanus elicited e.p.ps of very variable amplitude, no facilitation of response was shown to paired stimuli, and tetraethylammonium (0.5 mM) failed to increase e.p.p. amplitudes. 9 M.e.p.ps and e.p.ps were recorded at partially poisoned endplates in low Ca-high Mg solution. A reduction in the quantal content of evoked transmitter release was observed in comparison with controls. 10 M.e.p.ps recorded at partially and at fully intoxicated endplates showed an altered amplitude distribution with a higher proportion of large potentials. 11 It is concluded that P-C complex has a presynaptic site of action and may interfere with depolarization -secretion coupling at the motor nerve terminals.

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Section: Discussionmentioning

confidence: 99%

The Mode of Action at the Mouse Neuromuscular Junction of the Phospholipase A‐crotapotin Complex Isolated From Venom of the South American Rattlesnake

Hawgood

Smith

1977

British J Pharmacology

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“…Some snake toxins such as f3-bungarotoxin have also been found to cause depletion of synaptic vesicles at neuromuscular junctions (17), but it was found that nontransmitter substances were also released by this toxin (18). Because the nontransmitter, AIB, was not released by a-latrotoxin, it appears that a-latrotoxin is unique as a transmitter releasing agent.…”

Section: Methodsmentioning

confidence: 99%

Release of neurotransmitters and depletion of synaptic vesicles in cerebral cortex slices by alpha-latrotoxin from black widow spider venom.

Tzeng¹,

Cohen²,

Siekevitz³

1978

Proc. Natl. Acad. Sci. U.S.A.

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The effect of a-latrotoxin on cerebral cortex slices was studied by both biochemical and morphological methods. This toxin greatly stimulates the release of preloaded -y-amino[3H butyric acid from cortex slices. The response increases linearly with dose. The release is not dependent on the presence of extracellular Ca2+, and therefore it is not mediated by the release of other transmitters from other types of neurons. In contrast, no significant increase in the release of a nontransmitter substance a-amino[14Clisobutyric acid is observed. Since previously we have shown that a-latrotoxin stimulated the re ease of acetylcholine and norepinephrine from cortex slices, it appears that the toxin probably selectively releases all neurotransmitters. The toxin also profoundly depletes the synaptic vesicle population in boutons in the cortex slices. The results suggest that the release of neurotransmitter and the depletion of synaptic vesicle in boutons are manifestations of a single action of the toxin. Therefore, a-latrotoxin can be used as a good tool for the identification of neurotransmitters and in studies on the mechanism of neurotransmitter release.Previous work (1) has described the fractionation of an extract of the black widow spider venom gland (BWSV) into several toxic protein fractions. One of the fractions was purified to the degree of no detectable contaminating proteins and was recently named a-latrotoxin (2). This single toxin factor was demonstrated to be responsible for all the effects of BWSV on frog and mouse neuromuscular junctions, namely, the increase in the frequency of miniature end-plate potentials, the complete depletion of synaptic vesicles in the nerve terminals (boutons), and the ultimate blockage of neuromuscular transmission (1). Since BWSV has many actions on both vertebrates and invertebrates, particularly their nervous systems (reviewed in ref. 1), and since several toxic fractions have been found in the venom, it is of interest to investigate the spectrum of action of this highly purified a-latrotoxin in a single species. In a previous communication (2) we demonstrated that a-latrotoxin caused an increase in the release of both acetylcholine and norepinephrine (NE) from cerebral cortex slices of mouse. We report here: (i) that a-latrotoxin enhances the release of another putative neurotransmitter, -y-aminobutyric acid (GABA), from mouse cortical slices, but not the release of a non-transmitter substance, a-aminoisobutyric acid (AIB, an analogue of GABA); and (ii) that, as in the case of neuromuscular junction, it also causes depletion of synaptic vesicles in cerebral cortex slices. MATERIALS AND METHODSThe purification and assay of purity of a-latrotoxin were performed as described (1); occasionally another step of Sephadex G-200 chromatography was carried out after the DEAESephadex step to ensure homogeneity of the toxin.For each experiment, one male mouse (25-30 g) was killed by decapitation and its brain quickly removed. One slice was taken with a blade and blade guide fro...

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“…wts. of 13 000 and 7500 which are linked by S-S bridges (Howard and Gundersen, 1980;Kelly and Brown, 1974;Wernicke et al, 1975). In common with other snake venom neurotoxins, the larger subunit carries a Ca2+-dependent phospholipase A2 activity (Strong et al, 1976 cross-linked membranes were subjected to SDS-polyacrylamide gel electrophoresis (SDS-PAGE) under reducing conditions.…”

Section: Introductionmentioning

confidence: 99%

Identification by cross-linking of a beta-bungarotoxin binding polypeptide in chick brain membranes.

Rehm¹,

Betz²

1983

The EMBO Journal

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beta‐Bungarotoxin (beta‐BTX) is a snake venom neurotoxin which inhibits neurotransmitter release from different types of nerve terminals. To identify presynaptic membrane components potentially important in neurosecretion, 125I‐labeled beta‐BTX (mol. wt. 21 000) was cross‐linked to a high‐affinity binding site in synaptic membrane fractions of chick brain using the photoactivable cross‐linker N‐succinimidyl‐6(4′‐azido‐2′‐nitrophenylamino)‐hexanoate. Electrophoretic analysis of the cross‐linked membrane proteins under both reducing and non‐reducing conditions revealed a single [125I]beta‐BTX‐polypeptide adduct of apparent mol. wt. 116 000 (+/‐ 2000). The labeling of this band was prevented under conditions previously shown to inhibit the binding of [125I]beta‐BTX to its high‐affinity binding site. It is concluded that the cross‐linking procedure identified a polypeptide of the presynaptic binding site for beta‐BTX, and that this polypeptide has a mol. wt. of 95 000.

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The MECHANISM OF ACTION OF Β‐BUNGAROTOXIN

Cited by 129 publications

References 43 publications

The Mode of Action at the Mouse Neuromuscular Junction of the Phospholipase A‐crotapotin Complex Isolated From Venom of the South American Rattlesnake

The Mode of Action at the Mouse Neuromuscular Junction of the Phospholipase A‐crotapotin Complex Isolated From Venom of the South American Rattlesnake

Release of neurotransmitters and depletion of synaptic vesicles in cerebral cortex slices by alpha-latrotoxin from black widow spider venom.

Identification by cross-linking of a beta-bungarotoxin binding polypeptide in chick brain membranes.

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