Spider toxin (JSTX-3) inhibits the convulsions induced by glutamate agonists.

The effect of a spider toxin (JSTX-3)--a specific blocker of glutamate receptors--on the behavior of mice was studied using an intracerebroventricular (i.c.v.) injection technique. At higher doses (more than 12 nmol/brain), JSTX-3 increased motor activities and induced characteristic symptoms. JSTX-3 at a dose of 4.7 nmol/brain which per se did not produce any abnormal behavior, specifically antagonized quisqualate-induced convulsions but not NMDA- or kainate-induced convulsions. These results indicate that JSTX-3 is a selective antagonist of the quisqualate receptors in the mammalian central nervous system.