title: In vivo processing of LVV-hemorphin-7 in rat brain and blood utilizing microdialysis combined with electrospray mass spectrometry.
abstract: In vivo microdialysis in combination with liquid chromatography/electrospray time-of-flight mass spectrometry was used to study the processing of LVV-hemorphin-7, an endogenous decapeptide with opioid activity, in rat brain and blood. A microdialysis probe (flow rate 0.4 microL/min) was used to both introduce LVV-hemorphin-7 into the striatum of the brain (1.0 pmol/microL) or the venous blood (10 pmol/microL) and to collect the metabolic products. LVV-hemorphin-7 was extracellularly metabolized in the striatum to form C-terminal fragments 2-10, 3-10, 4-10, 5-10, 6-10, 7-10, and N-terminal fragments 1-9, 1-8, 1-6. Infusion of the aminopeptidase inhibitor amastatin (1.0 pmol/microL) into the striatum, together with LVV-hemorphin-7, decreased the processing of LVV-hemorphin-7 to form C-terminal fragments 2-10, 3-10, 4-10, but increased the relative levels of fragment 5-10 and N-terminal fragments 1-9, 1-8 and 1-6. The major metabolic product from LVV-hemorphin-7 in the striatum was the C-terminal fragment 5-10, which may be processed by an endopeptidase not sensitive to amastatin. The LVV-hemorphin-7 infusion to the venous blood produced the C-terminal fragments 2-10, 3-10, 4-10, and 5-10, N-terminal fragment 1-9, and internal fragments 4-7 and 4-9. It is concluded that the combination of microdialysis and electrospray mass spectrometry provides a powerful tool for the study of extracellular metabolism and kinetic processes of complex reaction systems in vivo.
authors.affiliation: Department of Pharmaceutical Biosciences, Division of Biological Research on Drug Dependence, Uppsala University, Uppsala, Sweden.
authors.forename: Katarina Sanderson
authors.initials: KS
authors.lastname: Nydahl
authors.forename: Johan
authors.initials: J
authors.lastname: Pierson
authors.forename: Fred
authors.initials: F
authors.lastname: Nyberg
authors.forename: Richard M
authors.initials: RM
authors.lastname: Caprioli
authors.forename: Per E
authors.initials: PE
authors.lastname: Andrén
mesh_terms: D000818:Animals; D001774:Blood Chemical Analysis; D002853:Chromatography, Liquid; D006454:Hemoglobins / Q000378:metabolism*; D008297:Male; D017551:Microdialysis; D017072:Neostriatum / Q000378:metabolism*; D010446:Peptide Fragments / Q000097:blood* / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods
chemical_list: D006454:Hemoglobins; D010446:Peptide Fragments; C074309:LVV-hemorphin-7