title: Endogenous peptide Tyr-Pro-Trp-Gly-NH2 (Tyr-W-MIF-1) is transported from the brain to the blood by peptide transport system-1.
abstract: Tyr-W-MIF-1 (Tyr-Pro-Trp-Gly-NH2) is a recently isolated peptide that belongs to a larger family that includes Tyr-MIF-1 (Tyr-Pro-Leu-Gly-NH2) and MIF-1 (Pro-Leu-Gly-NH2). Despite similarities in structure, Tyr-MIF-1 and MIF-1 can act differently in behavioral, blood-brain barrier (BBB) transport, and receptor binding systems. Tyr-W-MIF-1, like Tyr-MIF-1, has both opiate and antiopiate activity, but may be more opiate-like than Tyr-MIF-1. Tyr-MIF-1, but not MIF-1, is transported from brain to blood by peptide transport system (PTS)-1. PTS-1 transports mainly Tyr-MIF-1 and methionine enkephalin, but does not transport amino acids, peptide fragments of Tyr-MIF-1, D-Tyr-MIF-1, or unrelated peptides and proteins. We tested whether Tyr-W-MIF-1 also was transported across the BBB and, if so, whether PTS-1 was involved. 125I-Tyr-W-MIF-1 had a half-time disappearance from the brain of 22.4 min. This is faster than the efflux occurring with non-saturable reabsorption of the cerebrospinal fluid and, therefore, is consistent with saturable transport, but it is slower than the efflux rate of Tyr-MIF-1, suggesting a less robust transport than for Tyr-MIF-1 Self-inhibition with excess unlabeled Tyr-W-MIF-1 confirmed a saturable component, with a dose of 4.2 nmol producing 50% inhibition.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Veterans Affairs Medical Center, New Orleans, La 70146.
authors.forename: W A
authors.initials: WA
authors.lastname: Banks
authors.forename: A J
authors.initials: AJ
authors.lastname: Kastin
authors.forename: C A
authors.initials: CA
authors.lastname: Ehrensing
mesh_terms: D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000494:pharmacology; D000535:Aluminum / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D001812:Blood-Brain Barrier / Q000187:drug effects / Q000502:physiology*; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism*; D006207:Half-Life; D007457:Iodine Radioisotopes; D009075:MSH Release-Inhibiting Hormone / Q000031:analogs & derivatives* / Q000097:blood / Q000378:metabolism; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D012701:Serotonin / Q000502:physiology
chemical_list: D002352:Carrier Proteins; D007457:Iodine Radioisotopes; C077532:tyrosyl-prolyl-tryptophyl-glycinamide; D012701:Serotonin; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D009075:MSH Release-Inhibiting Hormone; D000535:Aluminum