It has been reported that methamphetamine (METH) upregulates striatal neurotensin (NT) mRNA levels. The present in situ hybridization study demonstrates, using the dopamine D1 antagonist SCH23390 that this effect is mediated through D1 receptors. Sulpiride, a selective D2 antagonist, induces an upregulation of NT expression, which in some striatal areas is additive to the METH effect. This suggests the existence of at least two NT striatal neuronal populations. One, sensitive to D1 receptors, corresponds to the recently described striatonigral NT pathway. The second one, modulated by D2 receptors, may project to the globus pallidus and/or represent interneurones.