Comparative effects of neurotensin, neurotensin(8-13) and [D-Tyr 11]neurotensin applied into the ventral tegmental area on extracellular dopamine in the rat prefrontal cortex and nucleus accumbens

Abstract

Ejections of 10 −5–10 −3 M neurotensin into the ventral tegmental area increased dopamine efflux measured by electrochemical approaches in the prefrontal cortex of anaesthetized rats. In the same conditions, the effects evoked on dopamine efflux by 10 −5 M neurotensin(8-13) and [D-Tyr 11]neurotensin were different from each other and depended on the explored area: the prefrontal cortex and the caudal and rostral nucleus accumbens. In the prefrontal cortex, neurotensin(8-13) was as potent as neurotensin, whereas [D-Tyr 11]neurotensin was ineffective. In the caudal nucleus accumbens, when considering the initial intensity of the effect, neurotensin(8-13) and neurotensin appeared more potent than [D-Tyr 11]neurotensin. In contrast, in the rostral nucleus accumbens, neurotensin(8-13) was less potent than [D-Tyr 11]neurotensin and neurotensin. These results support the differential involvement of two pharmacologically distinct neurotensin receptor entities on ventral tegmental area neurons in the modulation of mesolimbic and mesocortical dopaminergic activity.