Neurotensin effects on evoked release of dopamine in slices from striatum,nucleus accumbens and prefrontal cortex in rat

Summary The effects of neurotensin (NT) on the K⁺-evoked release of endogenous and tritiated dopamine in striatum and on ³H-dopamine in slices from nucleus accumbens and prefrontal cortex were investigated. In striatum, NT (1–1000 nM) elicited a dose-dependent increase in endogenous and ³H-dopamine release. The dose-response curves were comparable with the two methods. Concerning the comparison of NT modulation of ³H-dopamine release in the three cerebral structures, the peptide induced a more marked effect in striatum with a maximal effect of 150% increase. In accumbens, NT (1–1000 nM) potentiated the K⁺-evoked 3H-dopamine release, but in contrast with striatum, the plateau corresponded to a 50% increase. In prefrontal cortex, NT (1–1000 nM) induced small but significant effects, with a maximal increase of 50% at 100 nM. Acetyl-NT (8–13) displayed an action similar to the natural peptide while NT (1–8) did not exhibit any effect, suggesting that the action of NT involved a receptor. The presence of tetrodotoxin did not alter the facilitating effects of NT in the three structures, indicating that interneurons were not involved in the action of NT. The comparison of the effects of NT showed that in terms of efficacy, NT induced an increase in dopamine release more marked in striatum than in nucleus accumbens and prefrontal cortex. These results are consistent with differences in NT receptors localization in these three dopaminergic structures.Send offprint request to: A. Boireau