Repeated methamphetamine-treatment alters brain sigma receptors.

The present study was undertaken to examine whether repeated exposure of rats to the psychostimulant drug, methamphetamine, induces changes in sigma receptor binding. A significant up-regulation (130-145% of control Bmax) of sigma receptors, labeled with [3H](+)pentazocine, was observed in the substantia nigra, frontal cortex and cerebellum of rats treated with methamphetamine (4.0 mg/kg per day; 10 days). These findings suggest that methamphetamine-induced psychosis may be associated with the up-regulation of sigma receptors in critical brain regions.