Concanavalin A increases N-methyl-D-aspartate-induced Ca2+ influx in cerebellar granule cells in culture.
Desensitization of glutamatergic receptors can be inhibited by various endogenous and/or exogenous agents e.g. by lectins. Effect of lectin, concanavalin A (con A) on N-methyl-D-aspartate (NMDA)-induced Ca2+ influx was studied in cultured cerebellar granule cells. Additionally the effect of con A on 3H-(+)-5-methyl-10,11-dihydro-5H-dibenzocyclohepten-5,10-imine maleate (3H-(+)MK-801) binding to NMDA receptors was investigated. Preincubation with con A enhanced NMDA efficacy (but not potency) to stimulate Ca2+ influx. The potency of MK-801 to inhibit NMDA effect was similar in both control and con A pretreated cells. Preincubation of cortical membranes with con A resulted in a robust decrease of Bmax 3H-MK-801 binding and modest decrease in affinity. This contradiction between Ca2+ influx and binding experiments may result from the difference in the subtype of NMDA receptors or different expression of con A action in both assays.
Danysz
W
W
Merz+Co, Frankfurt/Main, Germany.
Wroblewski
J T
JT
D000818:Animals; D001923:Brain Chemistry / Q000187:drug effects; D002118:Calcium / Q000378:metabolism*; D002132:Calcium Radioisotopes; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D003208:Concanavalin A / Q000494:pharmacology*; D016291:Dizocilpine Maleate / Q000494:pharmacology; D004357:Drug Synergism; D005998:Glycine / Q000037:antagonists & inhibitors / Q000494:pharmacology; D066298:In Vitro Techniques; D007700:Kinetics; D008566:Membranes / Q000187:drug effects / Q000378:metabolism; D016202:N-Methylaspartate / Q000378:metabolism / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects / Q000378:metabolism
D002132:Calcium Radioisotopes; D016194:Receptors, N-Methyl-D-Aspartate; D003208:Concanavalin A; D016202:N-Methylaspartate; D016291:Dizocilpine Maleate; D002118:Calcium; D005998:Glycine