A spider toxin (JSTX) inhibits L-glutamate uptake by rat brain synaptosomes.
Joro spider toxin (JSTX), a specific blocker of glutamate receptors, was found to exert a prominent suppressive action on the Na+-dependent binding of L-glutamate to synaptic membranes and on glutamate uptake by synaptosomes in a dose-dependent manner. In contrast, the synthesized 2,4-dihydroxyphenylacetylasparagine (2,4-DHPA-ASN), a common moiety of spider toxins, which has been shown to exhibit almost the same activity as intact JSTX with respect to the inhibition of Na+-independent glutamate binding to its synaptic membrane receptors, shows lower potency in inhibiting Na+-dependent binding and uptake of L-glutamate. From these findings, it is clear that JSTX has the ability to inhibit not only L-glutamate binding to its synaptic membrane receptors but also L-glutamate uptake by synaptosomes, and that polyamines linked to 2,4-DHPA-ASN in the molecule of spider toxins may participate in the inhibition of L-glutamate uptake.
Pan-Hou
H
H
Faculty of Pharmaceutical Sciences, Setsunan University, Osaka, Japan.
Suda
Y
Y
Sumi
M
M
Yoshioka
M
M
Kawai
N
N
D000818:Animals; D001180:Arthropod Venoms / Q000494:pharmacology*; D001224:Aspartic Acid / Q000494:pharmacology; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D005971:Glutamates / Q000493:pharmacokinetics*; D018698:Glutamic Acid; D008297:Male; D010648:Phenylacetates / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D013111:Spider Venoms / Q000494:pharmacology*; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism*
D001180:Arthropod Venoms; D005971:Glutamates; D010648:Phenylacetates; D013111:Spider Venoms; D001224:Aspartic Acid; D018698:Glutamic Acid; C054012:2,4-dihydroxyphenylacetic acid