TURNING BEHAVIOR INDUCED BY INTRASTRIATAL INJECTION OF NEUROTENSIN INMICE - SENSITIVITY TO NONPEPTIDE NEUROTENSIN ANTAGONISTS

The intrastriatal injection of neurotensin (10 pg/mouse) elicited vigo rous contralateral rotations which were not affected by disruption of dopaminergic transmission using 6-OHDA lesion of the striatum or syste mic administration of spiroperidol (0.03 mg/kg). SR 48692, a selective non-peptide antagonist of neurotensin receptor, produced the followin g pattern of changes: a significant antagonism of rotations was observ ed at 0.04 and 0.08 mg/kg i.p. followed by a reinstatement of rotation s at 0.16-0.64 mg/kg (at higher doses, a second antagonism occurred th at lacked stereoselectivity). The reinstatement of rotations observed at 0.16 and 0.32 mg/kg of SR 48692 was abolished by spiroperidol and 6 -OHDA lesions, suggesting the role of dopamine regulatory mechanisms.