title: Black widow spider venom-induced release of neurotransmitters: mammalian synaptosomes are stimulated by a unique venom component (alpha-latrotoxin), insect synaptosomes by multiple components.
abstract: Synaptosomes isolated from the rat brain corpus striatum and locust head and thoracic ganglia were loaded with radioactive neurotransmitter ([3H]dopamine and [3H]acetylcholine, respectively) and then treated with alpha-latrotoxin and other fractions (fractions C, D and E of Frontali et al.8) obtained by Sephadex G200 column chromatography from black widow spider venom gland homogenates. As shown by sodium dodecyl sulphate-polyacrylamide gel electrophoresis, alpha-latrotoxin is a high Mr protein, whereas fractions C-E are mixtures of several proteins, that include small amounts of contaminating alpha-latrotoxin (especially in fraction C). In rat synaptosomes alpha-latrotoxin induced massive neurotransmitter release, and some release was induced also by high concentrations of fractions C and D. These responses were blocked almost completely by a monospecific anti-alpha-latrotoxin serum, indicating that they were all due to alpha-latrotoxin. Release of [3H]acetylcholine from locust synaptosomes was induced by the various preparations investigated. alpha-Latrotoxin was about 10-fold less potent in locust than in rat synaptosomes. The effects of fractions C-E tended to disappear with storage. The most active batches of fractions C and E were even more potent than alpha-latrotoxin, while the D fraction was approximately 5-fold less potent. The anti-alpha-latrotoxin antiserum inhibited part of the responses elicited by fractions C and E, but left fraction D almost unaffected. Release by D and E fractions was maintained even when Ca2+ was removed from the incubation medium.(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D000109:Acetylcholine / Q000378:metabolism; D000818:Animals; D001180:Arthropod Venoms / Q000494:pharmacology*; D003342:Corpus Striatum / Q000187:drug effects / Q000378:metabolism; D004298:Dopamine / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D005724:Ganglia / Q000187:drug effects / Q000378:metabolism; D006110:Grasshoppers; D018377:Neurotransmitter Agents / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013111:Spider Venoms / Q000032:analysis / Q000494:pharmacology*; D013574:Synaptosomes / Q000187:drug effects* / Q000378:metabolism
chemical_list: D001180:Arthropod Venoms; D018377:Neurotransmitter Agents; D013111:Spider Venoms; C020763:alpha-latrotoxin; D000109:Acetylcholine; D004298:Dopamine; C038599:black widow spider venom