The intrastriatal perfusion with the neurotensin(1-13) [NT(1-13)] and its active fragment NT(8-13) on striatopallidal GABA leads to the increased striatal and pallidal GABA release, and this effect is antagonized by intrastriatal perfusion with the NT receptor antagonist. In other experiments, NT, NT (8-13) and [D-Tyr(11)] NT are applied into the ventral tegmental area on extracellular dopamine in the prefrontal cortex and nucleus accumbens of rats. In the prefrontal cortex, neurotensin(8-13) is as potent as neurotensin but ineffective in [D-Tyr(11)]neurotensin. In the caudal nucleus accumbens, neurotensin(8-13) and neurotensin appears more potent than [D-Tyr(11)]neurotensin. In contrast, in the rostral nucleus accumbens, neurotensin(8-13) is less potent than [D-Tyr(11)]neurotensin and neurotensin.