The σ ligand 1,3-di-o-tolylguanidine depresses amino acid-induced excitation non-selectively in rat brain

The σ ligand 1,3-di-o-tolylguanidine (DTG) has been applied by microiontophoresis to neurones in the rat hippocampal slice and to neurones in the neocortex and hippocampus of rats anaesthetised with urethane. DTG depressed the excitatory responses of cells to both N-methyl-D-aspartate (NMDA) and quisqualate on a majority of the units tested, in no case causing an enhancement. Haloperidol had no consistent effect of its own and did not prevent the depressant effect of DTG. It is concluded that in the preparations used, DTG did not selectively modify neuronal sensitivity to NMDA.