TY - JOUR T1 - Effects of the Abused Solvent Toluene on Recombinant N-Methyl-<span class="sc">d</span>-Aspartate and non-N-Methyl-<span class="sc">d</span>-Aspartate Receptors Expressed in<em>Xenopus</em> Oocytes JF - Journal of Pharmacology and Experimental Therapeutics JO - J Pharmacol Exp Ther SP - 334 LP - 340 VL - 286 IS - 1 AU - Silvia L. Cruz AU - Tooraj Mirshahi AU - Brian Thomas AU - Robert L. Balster AU - John J. Woodward Y1 - 1998/07/01 UR - http://jpet.aspetjournals.org/content/286/1/334.abstract N2 - Previous studies have shown that toluene, which is commonly abused, depresses neuronal activity and causes behavioral effects in both animals and man similar to those observed for ethanol. In this study, the oocyte expression system was used to test the hypothesis that toluene, like ethanol, inhibits the function of ionotropic glutamate receptors. Oocytes were injected with mRNA for specific N-methyl-d-aspartate (NMDA) or non-NMDA subunits and currents were recorded using conventional two-electrode voltage clamp. To enhance the low water solubility of toluene, drug solutions were prepared by mixing toluene with alkamuls (ethoxylated castor oil) at a 1:1 ratio (v:v) and diluting this mixture to the appropriate concentration with barium-containing normal frog Ringer solution. Alkamuls, up to 0.1%, had no significant effects on membrane leak currents or on NMDA-induced currents. Toluene, up to ∼9 mM, had only minor effects on membrane leak currents but dose-dependently inhibited NMDA-mediated currents in oocytes. The inhibition of NMDA receptor currents by toluene was rapid, reversible and the potency for toluene’s effects was subunit dependent. The NR1/2B subunit combination was the most sensitive with an IC50 value for toluene-induced inhibition of 0.17 mM. The NR1/2A and NR1/2C receptors were 6- and 12-fold less sensitive with IC50 values of 1.4 and 2.1 mM, respectively. In contrast, toluene up to ∼9 mM did not inhibit kainate-induced currents in oocytes expressing GluR1, GluR1+R2 or GluR6 subunits. These results suggest that some of the effects of toluene on neuronal activity and behavior may be mediated by inhibition of NMDA receptors. The American Society for Pharmacology and Experimental Therapeutics ER -