title: Transfer of opiorphin through a blood-brain barrier culture model.
abstract: Opioid peptides are potent analgesics with therapeutic potential in the treatment of acute and chronic pain. Their efficacy is limited by peptidases (enkephalinases). Opiorphin pentapeptide (QRFSR) is the first characterized human endogenous inhibitor of enkephalinases. The peptide is able to increase the binding and affinity of endogenous opiates to mu opioid receptors; thus, the mechanism of opiorphin may provide a new therapeutic approach in pain management. The analgesic effect of opiorphin was proven in several earlier published in vitro and in vivo studies. Our aim was to test the transfer of opiorphin through a blood-brain barrier model for the first time. The flux of opiorphin was tested on a blood-brain barrier culture model consisting of rat brain endothelial, glial and pericyte cells. Brain endothelial cells in this triple co-culture model form tight monolayers characterized by transendothelial electrical resistance measurement. Relative quantity of the peptide was estimated by mass spectrometry. The transfer of opiorphin through the blood-brain barrier model was estimated to be ∼3%, whereas the permeability coefficient was 0.53 ± 1.36 × 10(-6) cm/s (n = 4). We also observed rapid conversion of N-terminal glutamine into pyroglutamic acid during the transfer experiments. Our results indicate that opiorphin crosses cultured brain endothelial cells in the absence of serum factors in a significant amount. This is in agreement with previous in vivo data showing potentiation of enkephalin-mediated antinociception. We suggest that opiorphin may have a potential as a centrally acting novel drug to treat pain.
authors.affiliation: Institute of Biophysics, Biologial Research Centre, Hungarian Academy of Sciences, Szeged, Hungary.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Bocsik
authors.affiliation: Institute of Biochemistry, Biologial Research Centre, Hungarian Academy of Sciences, Szeged, Hungary.
authors.forename: Zsuzsanna
authors.initials: Z
authors.lastname: Darula
authors.affiliation: Institute of Biochemistry, Biologial Research Centre, Hungarian Academy of Sciences, Szeged, Hungary.
authors.forename: Géza
authors.initials: G
authors.lastname: Tóth
authors.affiliation: Institute of Biophysics, Biologial Research Centre, Hungarian Academy of Sciences, Szeged, Hungary. Electronic address: deli.maria@brc.mta.hu.
authors.forename: Mária A
authors.initials: MA
authors.lastname: Deli
authors.affiliation: Institute of Biochemistry, Biologial Research Centre, Hungarian Academy of Sciences, Szeged, Hungary. Electronic address: wolleman.maria@brc.mta.hu.
authors.forename: Mária
authors.initials: M
authors.lastname: Wollemann
mesh_terms: D000700:Analgesics / Q000627:therapeutic use*; D000818:Animals; D001812:Blood-Brain Barrier / Q000737:chemistry*; D001921:Brain / Q000166:cytology / Q000378:metabolism*; D042783:Endothelial Cells / Q000378:metabolism*; D006801:Humans; D009842:Oligopeptides / Q000627:therapeutic use*; D018847:Opioid Peptides / Q000737:chemistry*; D051381:Rats; D017208:Rats, Wistar; D012471:Salivary Proteins and Peptides / Q000627:therapeutic use*
chemical_list: D000700:Analgesics; D009842:Oligopeptides; D018847:Opioid Peptides; D012471:Salivary Proteins and Peptides; C517879:glutaminyl-arginyl-phenylalanyl-seryl-arginine
keywords: Blood-brain barrier; Brain endothelial cell; LC-MS; Opiorphin; Peptidase inhibitor; Permeability