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Blood–brain barrier transport of a novel µ 1 ‐specific opioid peptide, H ‐Tyr‐ d ‐Arg‐Phe‐β‐Ala‐OH (TAPA)
Author(s) -
Deguchi Yoshiharu,
Miyakawa Yusaku,
Sakurada Shinobu,
Naito Yu,
Morimoto Kazuhiro,
Ohtsuki Sumio,
Hosoya Kenichi,
Terasaki Tetsuya
Publication year - 2003
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.2003.01582.x
Subject(s) - blood–brain barrier , endocytosis , chemistry , endothelial stem cell , peptide , internalization , receptor , in vitro , biochemistry , endocrinology , biology , central nervous system
The purpose of this study was to clarify the mechanism of the blood–brain barrier (BBB) transport of H ‐Tyr‐ d ‐Arg‐Phe‐β‐Ala‐OH (TAPA), which is a novel dermorphin analog with high affinity for the µ 1 ‐opioid receptor. The in vivo BBB permeation influx rate of [ 125 I]TAPA after an i.v. bolus injection (7.3 pmol/g body weight) into mice was estimated to be 0.265 ± 0.025µL/(min · g of brain). The influx rate of [ 125 I]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 [ 125 I]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 µ m . 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.