Pre-exposure to L-homocysteinesulfinic acid blocks quisqualate-induced sensitization to L-2-amino-4-phosphonobutanoic acid.
Quisqualic acid sensitizes hippocampal CA1 neurons to depolarization by L-2-amino-4-phosphonobutanoic acid (L-AP4). This sensitization to L-AP4 is known to be blocked by simultaneous exposure to L-homocysteinesulfinic acid, L-alpha-aminoadipic acid and L-serine-O-sulfate during exposure to quisqualate. We report here that these compounds also act as 'pre-blockers' which, when added and removed from the medium prior to exposure to quisqualate, prevent subsequent induction of sensitization to L-AP4 by quisqualate. This pre-blockade suggests that simple competitive inhibition of extracellular receptor or uptake sites may not be the mechanism by which these compounds attenuate the action of quisqualate in this 'Quis-effect'.
Whittemore
E R
ER
Department of Biochemistry and Neuroscience Graduate Program, University of Minnesota, Minneapolis 55455.
Koerner
J F
JF
D000200:Action Potentials / Q000187:drug effects; D000613:Aminobutyrates / Q000494:pharmacology*; D000818:Animals; D006624:Hippocampus / Q000187:drug effects; D006710:Homocysteine / Q000031:analogs & derivatives* / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D016318:Quisqualic Acid / Q000037:antagonists & inhibitors*; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors
D000613:Aminobutyrates; D006710:Homocysteine; C010982:homocysteinesulfinic acid; D016318:Quisqualic Acid; C012729:2-amino-4-phosphonobutyric acid