title: Antidepressant-like effects of the nociceptin/orphanin FQ receptor antagonist UFP-101: new evidence from rats and mice.
abstract: Receptor antagonist and knockout studies have demonstrated that blockade of signalling via nociceptin/orphanin FQ (N/OFQ) and its receptor (NOP) has antidepressant-like effects in mice submitted to the forced swimming test (FST). The aim of the present study was to explore further the antidepressant-like properties of the NOP antagonist UFP-101 in different species (mouse and rat) and using different assays [FST and tail suspension test (TST)], and to investigate the mechanism(s) involved in its actions.UFP-101 (10 nmol i.c.v.) reduced immobility time of Swiss mice in the TST (mean+/-SEM) from 179+/-11 to 111+/-10 s. N/OFQ (1 nmol i.c.v.) was without effect per se, but fully prevented the effect of UFP-101. The spontaneous immobility time of NOP(-/-) CD1-C57BL/6J-129 mice in the TST was much lower than that of wild-type (NOP(+/+)) littermates (75+/-11 vs. 144+/-17 s) or of Swiss mice. UFP-101 (10 nmol i.c.v.) decreased immobility time (-65%) and increased climbing time (71%) in rats submitted to the FST. In rat brain slices, N/OFQ (100 nM) triggered robust K(+)-dependent hyperpolarizing currents in locus coeruleus and dorsal raphe neurons. UFP-101 (3 microM) fully prevented N/OFQ-induced currents, but was inactive per se. Fluoxetine, desipramine (both 30 mg/kg i.p.) and UFP-101 (10 nmol i.c.v.) reduced immobility time of mice in the FST. The serotonin synthesis inhibitor p-chlorophenylalanine methylester (PCPA, 4 x 100 mg/kg per day i.p.) prevented the antidepressant-like effects of fluoxetine and UFP-101 (but not desipramine), whereas N-(2-chloroethyl)- N-ethyl-2-bromobenzylamine (DSP-4, neurotoxic for noradrenergic neurons; 50 mg/kg i.p., 7 days beforehand), suppressed only the effect of desipramine. Neither pretreatment affected spontaneous immobility time per se.Thus, UFP-101 exhibits pronounced antidepressant-like effects in different species and animal models, possibly by preventing the inhibitory effects of endogenous N/OFQ on brain monoaminergic (in particular serotonergic) neurotransmission. Participation of the N/OFQ-NOP receptor system in mood modulation sets new potential targets for antidepressant drug development.
authors.affiliation: Department of Experimental and Clinical Medicine, Section of Pharmacology and Neuroscience Center, University of Ferrara, via Fossato di Mortara 19, 44100 Ferrara, Italy.
authors.forename: E C
authors.initials: EC
authors.lastname: Gavioli
authors.forename: C W
authors.initials: CW
authors.lastname: Vaughan
authors.forename: G
authors.initials: G
authors.lastname: Marzola
authors.forename: R
authors.initials: R
authors.lastname: Guerrini
authors.forename: V A
authors.initials: VA
authors.lastname: Mitchell
authors.forename: S
authors.initials: S
authors.lastname: Zucchini
authors.forename: T C M
authors.initials: TC
authors.lastname: De Lima
authors.forename: G A
authors.initials: GA
authors.lastname: Rae
authors.forename: S
authors.initials: S
authors.lastname: Salvadori
authors.forename: D
authors.initials: D
authors.lastname: Regoli
authors.forename: G
authors.initials: G
authors.lastname: Calo'
mesh_terms: D000818:Animals; D000928:Antidepressive Agents / Q000494:pharmacology*; D001921:Brain / Q000187:drug effects / Q000502:physiology; D004594:Electrophysiology; D019417:Hindlimb Suspension / Q000502:physiology; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D009292:Narcotic Antagonists; D018847:Opioid Peptides / Q000494:pharmacology*; D051381:Rats; D011957:Receptors, Opioid / Q000819:agonists / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects; D013550:Swimming / Q000502:physiology; D000094942:Nociceptin Receptor; D000097629:Nociceptin
chemical_list: D000928:Antidepressive Agents; D009292:Narcotic Antagonists; D018847:Opioid Peptides; D011957:Receptors, Opioid; D000094942:Nociceptin Receptor; D000097629:Nociceptin; C479838:(Nphe(1),Arg(14),Lys(15))N-OFQ NH(2)