Regulation of NT Receptors after Chronic Treatment with Typical and Atypical Neuroleptic Drugs

Abstract

Neurotensin is a tridecapeptide, which produces central effects such as hypotension, hypothermia, muscle relaxation, analgesia, antinociception, and reduces locomotor activity (Nemeroff et al., 1977). In the recent years, several lines of evidences indicated the great importance of the dopamine (DA)- neurotensin (NT) interaction taking place mostly in the mesolimbocortical areas, both at cell bodies (A10 DA-ergic group located in the ventral tegmental area -VTA-) and nerve terminal level (cerebral cortex, n. accumbens, olfactory tubercle, ventral n. caudato-putamen) (Quirion, 1983; Nemeroff, et al., 1984; Nemeroff, 1986). Immunocytochemical data indicated the presence of NT-like immunoreactivity in DA cell bodies in the VTA, including midline structures, with only single example of coexistence in the substantia nigra (Hokfelt et al., 1984). Anatomical data indicate that NT-like immunoreactive fibres, nerve terminals and also cell bodies are present in the basal ganglia (Kalivas, 1984; Sugimoto and Mizuno, 1987; Uhl et al, 1979). NT receptors are localized on the DA-ergic cell bodies in the ventral mesencephalon (Young and Kuhar, 1981). NT receptors are also reported to exist in the basal ganglia of the rat, on DA nerve terminals, intrinsic neurons and corticostriatal fibres (FIG. 1) (Quirion et al, 1985; Goedert et al., 1984).