[Neurotensin, dopamine and mode of action of neuroleptics]

It has new been almost ten years since interactions between the neurotensinergic and dopaminergic neuronal systems were first described. These results have now been confirmed on anatomical and biochemical as well as on behavioural grounds. First, we describe experiments showing that ascending dopaminergic pathways control the density of neurotensinergic binding sites in structures such as prefrontal cortex, nucleus accumbens and striatum. Secondly, we attempt to elucidate the consequences that such receptor hetero-regulations, together with the presence of mixed neurotensin/dopamine fibers in the prefrontal cortex, might have on the mode of action of neuroleptic drugs. Indeed, by blocking dopamine receptors, neuroleptics might bring about long-term and heterogeneous changes in the transmission of non dopaminergic systems in those projection areas possessing dopamine receptors. The new functional hierarchies thus produced between dopamine innervated structures might then explain the therapeutic action of neuroleptics.