Neurotensin potentiates the potassium-induced release of endogenous dopamine from rat striatal slices.

The effects of neurotensin on the release of endogenous dopamine (DA) from rat striatal slices were investigated. DA was extracted by the aluminium adsorption method and assayed electrochemically by high-performance liquid chromatography. Neurotensin (2-100 microM) potentiated the potassium-induced release of striatal endogenous DA in a concentration-dependent manner. This neurotensin-induced release of DA was completely abolished in calcium-free medium containing EGTA 1 mM. The presence of tetrodotoxin 2 microM did not alter the effect of neurotensin 10 microM. On the other hand, neurotensin did not affect the uptake of [3H]DA into the striatal slices. In additional experiments, we confirmed that the KCl-induced release of DA in the nucleus accumbens was also potentiated b neurotensin. These results suggest that neurotensin has a direct effect on the central DA nerve terminals and releases DA in a Ca2+-dependent manner.