Behavioral effects of neurotensin applied to periventricular structures of rats.

Neurotensin (NT), an active neuropeptide, and bicuculline, a GABA-A receptor antagonist, were microinjected into the rat medial hypothalamus (MH) or the dorsal periaqueductal gray matter (DPAG). Bicuculline (80 pmol) produced behavioral activation which included jumping and NT (1-20 nmol) caused a dose-dependent behavioral activation accompanied by catalepsy rather than jumping. These results suggest that the behavioral activation produced by NT may be due to an interaction of the neuropeptide with specific receptors while its cataleptic effect may be attributed to the blockade of dopamine receptors.