Domoic acid enhances the K(+)-evoked release of endogenous glutamate from guinea pig hippocampal mossy fiber synaptosomes.
The presynaptic effects of domoic acid (Dom) on hippocampal mossy fiber synaptic transmission were examined using a subcellular fraction enriched in mossy fiber synaptosomes. Domoic acid significantly increased the K(+)-evoked release of endogenous glutamate from superfused guinea pig mossy fiber synaptosomes. The presynaptic facilitation produced by Dom was dose-dependent and was antagonized by the prior application of 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX). At a concentration of 30 microM, both domoic acid and kainic acid significantly increased the extent to which membrane depolarization augmented the availability of cytosolic free calcium in mossy fiber synaptosomes. These results are consistent with the suggestion that domoic acid enhances the release of mossy fiber neurotransmitters in the guinea pig hippocampus through the activation of a CNQX-sensitive presynaptic receptor.
Department of Anatomy and Cell Biology, East Carolina University School of Medicine, Greenville, NC 27858.
D M
DM
Terrian
T A
TA
Conner-Kerr
T H
TH
Privette
R L
RL
Gannon
D018750:6-Cyano-7-nitroquinoxaline-2,3-dione; D000818:Animals; D002118:Calcium / Q000378:metabolism; D004357:Drug Synergism; D005971:Glutamates / Q000378:metabolism*; D018698:Glutamic Acid; D006168:Guinea Pigs; D006624:Hippocampus / Q000378:metabolism*; D007608:Kainic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D008297:Male; D009412:Nerve Fibers / Q000378:metabolism*; D011188:Potassium / Q000494:pharmacology*; D011810:Quinoxalines / Q000494:pharmacology; D013574:Synaptosomes / Q000378:metabolism*
D005971:Glutamates; D011810:Quinoxalines; D018698:Glutamic Acid; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione; C012301:domoic acid; D011188:Potassium; D007608:Kainic Acid; D002118:Calcium