ACUTE AMPHETAMINE OR METHAMPHETAMINE ALTERS OPIOID PEPTIDE MESSENGER-RNA EXPRESSION IN RAT STRIATUM

The effects of a single dose of amphetamine or methamphetamine on opio id peptide gene expression in the dorsal and ventral striatum of rats were investigated by quantitative in situ hybridization 3, 6, or 18 h after injection. Although amphetamine-treated rats exhibited significa ntly different behaviors than those treated with methamphetamine, both drugs caused a patchy increase in preprodynorphin, but not preproenke phalin, mRNA in the caudate at air 3 time points. No changes were dete cted in the nucleus accumbens. These data indicate that prolonged elev ation of preprodynorphin expression may alter the responsiveness of st riatonigral neurons to subsequent amphetamine exposure.