Neurotensin-induced modulation of dopamine D2 receptors and their function in rat striatum:: Counteraction by a NTRI-like receptor antagonist

The present study investigated the neurotensin (NT) receptor subtype (NTR) involved in the antagonistic neurotensin modulation of striatal dopamine D2 receptors observed in vitro and in vivo. The NT induced increase of the IC50 values of dopamine (DA) competition for [I-125]iodosulpiride binding sites was counteracted by the NTRI-like antagonist SR48692 in rat striatal slices. Intrastriatal perfusion of pergolide induced in the awake rat an inhibition of striatal DA release that was antagonized by NT. This action of NT was counteracted by co-perfusion with the NTRI like antagonist SR48692. These data indicate that there exists in the striatum at the prejunctional level an intramembrane antagonistic NT receptor/DA D2 receptor-receptor interaction where NTRI like receptor activation reduces the DA D2 autoreceptor function. NeuroReport 13: 763-766 (C) 2002 Lippincott Williams Wilkins.