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Neurotensin analogs (D-TYR11) and (D-PHE11)neurotensin resist degradation by brain peptidases in vitro and in vivo

Journal Article · · J. Pharmacol. Exp. Ther.; (United States)
OSTI ID:6541708
The present study was designed to compare the susceptibility of neurotensin (NT), (/sup 3/H)NT, (D-Tyr11)NT and (D-Phe11)NT to degradation by 1) rat brain synaptic membranes in vitro and 2) after i.c.v. administration in the rat in vivo. Degradation was assessed by purifying the peptides using reverse phase high-performance liquid chromatography and by measuring the amount of radioactive or absorbing (OD 230) material under each peptide peak. In contrast to NT, (D-Tyr11)NT and (D-Phe11)NT were resistant to degradation by brain synaptic peptidases in vitro. Furthermore, NT was rapidly metabolized in brain tissues after i.c.v. administration, whereas (D-Tyr11)NT was metabolically stable. The present data confirm the central role of NT residue Tyr11 in the mechanisms of NT inactivation by brain synaptic peptidases. They account for the higher in vivo potency of (D-Tyr11)NT as compared with its in vitro potency. Finally, they explain, at least in part, the need to administer large doses of NT in the brain in order to observe neurobehavioral and neuropharmacological effects.
Research Organization:
Centre National de la Recherche Scientifique, Nice, France
OSTI ID:
6541708
Journal Information:
J. Pharmacol. Exp. Ther.; (United States), Journal Name: J. Pharmacol. Exp. Ther.; (United States) Vol. 227:3; ISSN JPETA
Country of Publication:
United States
Language:
English