A toxic extract of the marine phytoflagellate Prymnesium parvum induces calcium-dependent release of glutamate from rat brain synaptosomes.
Blooms of the marine phytoflagellate Prymnesium parvum produced mass mortality of fish in Norway and many other parts of the world. The effects of a purified algae extract of P. parvum on transmitter release from rat brain synaptosomes were studied to characterize its toxic action. Synaptosomes are detached nerve terminals and represent a simple system that has retained the machinery for uptake, synthesis, storage, and release of neurotransmitters. A crude methanol extract of P. parvum was purified by reverse-phase column for fast protein liquid chromatography (FPLC). The purified extract stimulated Ca2+-dependent spontaneous release of glutamate in a concentration-dependent manner. The release was increased by addition of extracellular Ca2+. The release of glutamate was suppressed by the Ca2+-channel blockers flunarizine (10 microM), diltiazem (10 microM), and verapamil (10 microM). The stimulation of release of glutamate from rat brain synaptosomes induced by the toxin may be due to an ionophorelike property of the algae extract such as previously reported for the potent algal toxin maitotoxin. At high concentrations the toxin primarily acts as a powerful lytic agent.
Mariussen
Espen
E
Norwegian Institute for Air Research, Kjeller, Norway. Espen.Mariussen@nilu.no
Nelson
George Nicholas
GN
Fonnum
Frode
F
D000818:Animals; D001923:Brain Chemistry / Q000187:drug effects*; D002118:Calcium / Q000502:physiology*; D004912:Erythrocytes / Q000187:drug effects; D056890:Eukaryota / Q000737:chemistry*; D018698:Glutamic Acid / Q000378:metabolism*; D006461:Hemolysis / Q000187:drug effects; D006801:Humans; D066298:In Vitro Techniques; D008387:Marine Toxins / Q000633:toxicity*; D009498:Neurotoxins / Q000633:toxicity*; D035964:Oxocins / Q000633:toxicity; D051381:Rats; D017208:Rats, Wistar; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism*; D000095702:Polyether Toxins
D002118:Calcium; D018698:Glutamic Acid; D008387:Marine Toxins; D009498:Neurotoxins; D035964:Oxocins; C020394:maitotoxin; D000095702:Polyether Toxins