In vivo transport of a dynorphin-like analgesic peptide, E-2078, through the blood-brain barrier: an application of brain microdialysis

• Published in: Pharmaceutical research 1991-07, Vol.8 (7), p.815-820
• Main Authors: Terasaki, T, Deguchi, Y, Sato, H, Hirai, K, Tsuji, A
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; Blood Volume - physiology; Blood-Brain Barrier - physiology; Brain Chemistry - physiology; Capillaries - physiology; Chromatography, High Pressure Liquid; Dialysis; Dynorphins - analogs & derivatives; Dynorphins - pharmacokinetics; Endocytosis - physiology; Male; Molecular Sequence Data; Peptide Fragments - pharmacokinetics; Perfusion; Rats; Rats, Inbred Strains; Tyrosine - pharmacology
• ISSN: 0724-8741
• DOI: 10.1023/a:1015882924470

In vivo transport through the blood-brain barrier (BBB) has been demonstrated for a dynorphin-like analgesic peptide, CH3-[125I]Tyr-Gly-Gly-Phe-Leu-Arg-CH3Arg-D-Leu-NHC2H5 ( [125I]E-2078). A remarkable time-dependent increase in the distribution volume of [125I]E-2078 in the brain parenchyma separated from blood vessels and capillaries was observed during a brain perfusion. The distribution volume of [125I]E-2078 in the brain parenchyma after 20 min of perfusion was 2.18 +/- 0.09 microliters/g brain (mean +/- SE) and was significantly greater than the distribution volume of [3H]inulin (0.994 +/- 0.138 microliters/g brain), providing in vivo evidence for the penetration of [125I]E-2078 into the brain parenchyma. Brain microdialysis was carried out to collect directly the brain interstitial fluid (ISF) during the brain perfusion of [125I]E-2078. No metabolite of [125I]E-2078 in the brain ISF was found by high-performance liquid chromatographic analysis of the brain dialysate. The concentrations of [125I]E-2078 and [14C]sucrose in the brain ISF were estimated based on an in vitro evaluation of dialysis clearance. The concentration ratio of [125I]E-2078 between the brain ISF and the brain perfusate was determined to be 2.92 x 10(-1) +/- 0.50 x 10(-1) and was approximately 100 times higher than that of [14C]sucrose (2.71 x 10(-3) +/- 1.43 x 10(-3), demonstrating transport of [125I]E-2078 through the BBB in vivo. On the other hand, no remarkable difference in the cerebrospinal fluid (CSF)-to-perfusate concentration ratios of [125I]E-2078 and [14C]sucrose was observed, indicating little contribution of the blood-CSF barrier (BCSF barrier) transport to the penetration of [125I]E-2078 into the brain.