title: Blood-brain barrier transport of a novel micro 1-specific opioid peptide, H-Tyr-D-Arg-Phe-beta-Ala-OH (TAPA).
abstract: The purpose of this study was to clarify the mechanism of the blood-brain barrier (BBB) transport of H-Tyr-D-Arg-Phe-beta-Ala-OH (TAPA), which is a novel dermorphin analog with high affinity for the micro 1-opioid receptor. The in vivo BBB permeation influx rate of [125I]TAPA after an i.v. bolus injection (7.3 pmol/g body weight) into mice was estimated to be 0.265 +/- 0.025 microL/(min.g of brain). The influx rate of [125I]TAPA was reduced 70% by the coadministration of unlabeled TAPA (33 nmol/g of brain), suggesting the existence of a specific transport system for TAPA at the BBB. In order to elucidate the BBB transport mechanism of TAPA, a conditionally immortalized mouse brain capillary endothelial cell line (TM-BBB4) was used as an in vitro model of the BBB. The acid-resistant binding of [125I]TAPA, which represents the internalization of the peptide into cells, was temperature- and concentration-dependent with a half-saturation constant of 10.0 +/- 1.7 microm. The acid-resistant binding of TAPA was significantly inhibited by 2,4-dinitrophenol, dansylcadaverine (an endocytosis inhibitor) and poly-l-lysine and protamine (polycations). These results suggest that TAPA is transported through the BBB by adsorptive-mediated endocytosis, which is triggered by binding of the peptide to negatively charged sites on the surface of brain capillary endothelial cells. Blood-brain barrier transport via adsorptive-mediated endocytosis plays a key role in the expression of the potent opioid activity of TAPA in the CNS.
authors.affiliation: Department of Drug Disposition and Pharmacokinetics, School of Pharmaceutical Sciences, Teikyo University, 1091-1 Suarashi, Sagamiko-machi, Tsukui-gun, Kanagawa 199-0195, Japan. deguchi@pharm.teikyo-u.ac.jp
authors.forename: Yoshiharu
authors.initials: Y
authors.lastname: Deguchi
authors.forename: Yusaku
authors.initials: Y
authors.lastname: Miyakawa
authors.forename: Shinobu
authors.initials: S
authors.lastname: Sakurada
authors.forename: Yu
authors.initials: Y
authors.lastname: Naito
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Morimoto
authors.forename: Sumio
authors.initials: S
authors.lastname: Ohtsuki
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Hosoya
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Terasaki
mesh_terms: D019297:2,4-Dinitrophenol / Q000494:pharmacology; D000818:Animals; D001667:Binding, Competitive / Q000187:drug effects / Q000502:physiology; D001812:Blood-Brain Barrier / Q000502:physiology*; D001921:Brain / Q000098:blood supply; D002103:Cadaverine / Q000031:analogs & derivatives* / Q000494:pharmacology; D002196:Capillaries / Q000166:cytology; D002478:Cells, Cultured; D002851:Chromatography, High Pressure Liquid; D004705:Endocytosis / Q000187:drug effects; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007457:Iodine Radioisotopes; D051379:Mice; D008815:Mice, Inbred Strains; D009842:Oligopeptides / Q000032:analysis / Q000378:metabolism* / Q000493:pharmacokinetics; D010539:Permeability; D011073:Polyamines / Q000494:pharmacology; D000071228:Polyelectrolytes; D011108:Polymers / Q000494:pharmacology; D017450:Receptors, Opioid, mu / Q000378:metabolism*; D013696:Temperature
chemical_list: D019297:2,4-Dinitrophenol; D002103:Cadaverine; D007457:Iodine Radioisotopes; D009842:Oligopeptides; D011073:Polyamines; D000071228:Polyelectrolytes; D011108:Polymers; D017450:Receptors, Opioid, mu; C412736:tyrosyl-arginyl-phenylalanyl-beta--alanine; C008542:monodansylcadaverine