title: Antinociceptive profile of LP1, a non-peptide multitarget opioid ligand.
abstract: OBJECTIVE
  Opioid drugs are the principal treatment option for moderate to severe pain and exert their biological effects through interactions with opioid receptors that are widely distributed throughout the CNS and peripheral tissues. Ligands capable of simultaneously targeting different receptors could be successful candidates for the treatment of chronic pain. Enhanced antinociception coupled with a low incidence of side effects has been demonstrated for ligands possessing mixed mu-opioid receptor (MOR) and delta-opioid receptor (DOR) activity. We previously reported that 3-[(2R,6R,11R)-8-hydroxy-6,11-dimethyl-1,4,5,6-tetrahydro-2,6-methano-3-benzazocin-3(2H)-yl]-N-phenylpropanamide (LP1) acted as a MOR-DOR ligand in in vitro functional assays and moreover this drug produced a valid antinociception that was longer lasting than that of morphine. The aim of this work was to determine whether the antinociceptive effect produced by LP1 was central or peripheral and to assess which opioid receptor subtypes are involved in its effects.
  
  
  METHODS
  We explored the effects of naloxone methiodide (NX-M), a quaternary opioid antagonist, administered either intracerebroventricularly (i.c.v.) or subcutaneously (s.c.), on LP1-mediated antinociception in male Sprague-Dawley rats. In addition, we administered s.c. selective antagonists for MOR, DOR and kappa-opioid receptor (KOR) to investigate the effects of LP1. To characterise this drug's DOR profile better, we also investigated the effects of LP1 on DPDPE, a selective DOR agonist.
  
  
  RESULTS
  Data obtained by tail flick test showed that LP1 induced predominantly MOR-mediated supraspinal antinociception and was able to counteract DPDPE analgesia.
  
  
  CONCLUSIONS
  LP1, a multitarget opioid ligand, is a supraspinal acting antinociceptive agent that is useful for the treatment of chronic pain.
authors.affiliation: Department of Drug Sciences, Pharmacology and Toxicology section, University of Catania, Viale A. Doria 6, 95125 Catania, Italy.
authors.forename: Carmela
authors.initials: C
authors.lastname: Parenti
authors.forename: Rita
authors.initials: R
authors.lastname: Turnaturi
authors.forename: Giuseppina
authors.initials: G
authors.lastname: Aricò
authors.forename: Agostino
authors.initials: A
authors.lastname: Marrazzo
authors.forename: Orazio
authors.initials: O
authors.lastname: Prezzavento
authors.forename: Simone
authors.initials: S
authors.lastname: Ronsisvalle
authors.forename: Giovanna M
authors.initials: GM
authors.lastname: Scoto
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Ronsisvalle
authors.forename: Lorella
authors.initials: L
authors.lastname: Pasquinucci
mesh_terms: D000700:Analgesics / Q000008:administration & dosage* / Q000378:metabolism; D000701:Analgesics, Opioid / Q000008:administration & dosage / Q000378:metabolism; D000818:Animals; D001575:Benzomorphans / Q000008:administration & dosage* / Q000378:metabolism; D016503:Drug Delivery Systems / Q000379:methods*; D008024:Ligands; D008297:Male; D010147:Pain Measurement / Q000187:drug effects* / Q000379:methods; D051381:Rats; D017207:Rats, Sprague-Dawley; D017465:Receptors, Opioid, delta / Q000819:agonists / Q000378:metabolism*; D017450:Receptors, Opioid, mu / Q000819:agonists / Q000378:metabolism*; D015203:Reproducibility of Results
chemical_list: C569975:3-((2R,6R,11R)-8-hydroxy-6,11-dimethyl-1,4,5,6-tetrahydro-2,6-methano-3-benzazocin-3(2H)-yl)-N-phenylpropanamide; D000700:Analgesics; D000701:Analgesics, Opioid; D001575:Benzomorphans; D008024:Ligands; D017465:Receptors, Opioid, delta; D017450:Receptors, Opioid, mu