title: Distribution in Rats Internal Organs of Intraperitoneally Given 125I-Labeled Heptapeptide [2-8]-Leucopyrokinin ([2-8]-LPK), a Truncated Analog of Insect Neuropeptide Leucopyrokinin.
abstract: BACKGROUND
  It was previously found that synthetic, insect-derived octapeptide leucopyrokinin (LPK) applied directly into the lateral brain ventricle induced a significant antinociceptive effect in rats. Its synthetic truncated analog heptapeptide [2-8]-leucopyrokinin displayed a stronger antinociceptive effect in comparison to native LPK. Moreover it was previously found a high accumulation of these both 125I-labeled peptides in adrenals, as well as in hypothalamus and in hippocampus of rats brain.
  
  
  OBJECTIVE
  The aim of the present study was to assess the distribution of 125I-labeled [2-8]-leucopyrokinin in rats' internal organs an in several parts of the brain after peripheral - intraperitoneal (i.p.) administration.
  
  
  METHODS
  The study was performed on male Wistar rats. A synthetic [2-8]-leucopyrokinin ([2-8]-LPK) was iodinated with Na125I. On the day of experiment a solution of 125I-[2-8]-LPK was i.p. injected and the next after 1 and 24 h animals were sacrificed by decapitation. Radioactivity levels in samples of parts of the brain and of internal organs were determined by counter Gamma Auto Count.
  
  
  RESULTS
  A uniform, low accumulation 125I-[2-8]-LPK was found in evaluated samples of the brain and in internal organs.
  
  
  CONCLUSIONS
  The results of the present study indicate a weak penetration into the brain and internal organs of intraperitoneally applied 125I-[2-8]-LPK in rats and correspond with previously determined weak biological effects of i.p. injected LPK and [2-8]-LPK.
authors.affiliation: Pharmaceutical Research and Production Plant, "Biochefa", Sosnowiec, Poland.
authors.forename: Florian
authors.initials: F
authors.lastname: Ryszka
authors.affiliation: Pharmaceutical Research and Production Plant, "Biochefa", Sosnowiec, Poland.
authors.forename: Barbara
authors.initials: B
authors.lastname: Dolińska
authors.affiliation: Department of Histology and Embriology, Medical University of Silesia, Katowice, Poland.
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Suszka-Świtek
authors.affiliation: Department of Toxicology and Health Protection, Medical University of Silesia, Katowice, Poland.
authors.forename: Monika
authors.initials: M
authors.lastname: Rykaczewska-Czerwińska
authors.affiliation: Faculty of Chemistry, University of Wroclaw, Poland.
authors.forename: Danuta
authors.initials: D
authors.lastname: Konopińska
authors.affiliation: Faculty of Chemistry, University of Wroclaw, Poland.
authors.forename: Mariola
authors.initials: M
authors.lastname: Kuczer
authors.affiliation: Higher School of Medicine in Sosnowiec, Poland.
authors.forename: Andrzej
authors.initials: A
authors.lastname: Plech
mesh_terms: D000311:Adrenal Glands / Q000378:metabolism; D000700:Analgesics / Q000008:administration & dosage* / Q000493:pharmacokinetics*; D000818:Animals; D006624:Hippocampus / Q000378:metabolism; D007031:Hypothalamus / Q000378:metabolism; D007274:Injections, Intraperitoneal; D008297:Male; D009479:Neuropeptides / Q000008:administration & dosage* / Q000493:pharmacokinetics*; D009842:Oligopeptides / Q000008:administration & dosage* / Q000493:pharmacokinetics*; D010446:Peptide Fragments / Q000008:administration & dosage* / Q000493:pharmacokinetics*; D010539:Permeability; D011761:Pyrrolidonecarboxylic Acid / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D017208:Rats, Wistar; D014018:Tissue Distribution
chemical_list: C000602685:125I-labeled heptapeptide(2-8)-leucopyrokinin; D000700:Analgesics; D009479:Neuropeptides; D009842:Oligopeptides; D010446:Peptide Fragments; D011761:Pyrrolidonecarboxylic Acid