ro-64-6198 and Disease-Models--Animal

Carrageenan-induced hyperalgesia is a widely used pain model in rodents. However, characteristics of carrageenan-induced hyperalgesia and effects of analgesic drugs under these conditions are unknown in nonhuman primates.. The aims of this study were to develop carrageenan-induced hyperalgesia in rhesus monkeys and determine the efficacy and potency of agonists selective for the four opioid receptor subtypes in this model versus acute pain, as compared to non-steroidal anti-inflammatory drugs (NSAIDs).. Tail injection of carrageenan produced long-lasting thermal hyperalgesia in monkeys. Systemically administered agonists selective for opioid receptor subtypes, i.e., fentanyl (mu/MOP), U-50488H (kappa/KOP), SNC80 (delta/DOP) and Ro 64-6198 (nociceptin/orphanin FQ/NOP) dose-dependently attenuated carrageenan-induced thermal hyperalgesia with different potencies. In absence of carrageenan, these agonists, except SNC80, blocked acute thermal nociception. Opioid-related ligands, especially Ro 64-6198, were much more potent for their antihyperalgesic than antinociceptive effects. Both effects were mediated by the corresponding receptor mechanisms. Only fentanyl produced scratching at antihyperalgesic and antinociceptive doses consistent with its pruritic effects in humans, illustrating a translational profile of MOP agonists in nonhuman primates. Similar to SNC80, systemically administered NSAIDs ketorolac and naproxen dose-dependently attenuated carrageenan-induced hyperalgesia but not acute nociception.. Using two different pain modalities in nonhuman primates, effectiveness of clinically available analgesics like fentanyl, ketorolac and naproxen was distinguished and their efficacies and potencies were compared with the selective KOP, DOP, and NOP agonists. The opioid-related ligands displayed differential pharmacological properties in regulating hyperalgesia and acute nociception in the same subjects. Such preclinical primate models can be used to investigate novel analgesic agents.

Topics: 3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; Acute Pain; Analgesics, Opioid; Animals; Anti-Inflammatory Agents, Non-Steroidal; Benzamides; Carrageenan; Disease Models, Animal; Dose-Response Relationship, Drug; Female; Fentanyl; Hyperalgesia; Imidazoles; Inflammation; Macaca; Male; Nociceptive Pain; Pain Measurement; Piperazines; Receptors, Opioid; Spiro Compounds

Ro 64-6198, the prototypical non-peptide nociceptin/orphanin FQ peptide (NOP) receptor agonist, has potent anxiolytic-like effects in several preclinical models and species. However the effects of Ro 64-6198 on distinctive anxiety-provoking conditions related to unconditioned conflict behavior as well as its role in despair-like behavior remain to be addressed.. Here we examined the effects of Ro 64-6198 on unconditioned conflict anxiety using stimuli with different salience and on regulation of autonomic reactivity and compared these to the effects of benzodiazepine receptor agonists. We also addressed the potential effects of Ro 64-6198 on despair-like behavior.. Ro 64-6198 (0.1 to 10 mg/kg i.p.) and either diazepam or chlordiazepoxide were tested in the Vogel conflict punished drinking test (VCT) in Sprague Dawley rats, in the social approach-avoidance (SAA) test in Lewis rats, in the novelty-induced hypophagia (NIH) in C57BL/6J mice, and in stress-induced hyperthermia in NMRI mice, as well as in the forced swim test (FST) in Sprague Dawley rats and the tail suspension test (TST) in C57BL/6J mice.. Ro 64-6198 (0.3 to 3 mg/kg) dose-dependently produced anxiolytic-like effects in the VCT, SAA, NIH, and SIH, similar to benzodiazepine receptor agonists. Ro 64-6198 did not alter immobility time in the FST and TST.. Ro 64-6198 produced marked anxiolytic-like effects in response to a variety of mild to strong anxiogenic stimuli, whereas it did not facilitate depression-related behaviors. This data extend previous literature suggesting that NOP receptors are a viable target for the treatment of anxiety disorders.

Topics: Animals; Anti-Anxiety Agents; Anxiety; Behavior, Animal; Chlordiazepoxide; Conflict, Psychological; Depression; Diazepam; Disease Models, Animal; Dose-Response Relationship, Drug; Imidazoles; Male; Mice; Mice, Inbred C57BL; Nociceptin Receptor; Rats; Rats, Inbred Lew; Rats, Sprague-Dawley; Receptors, Opioid; Spiro Compounds; Stress, Psychological

Nociceptin/orphanin-FQ (N/OFQ) peptide and its receptor (NOP: N/OFQ opioid peptide receptor) are highly expressed in the hippocampus, but their functional role remains poorly understood. We recently showed that hippocampal N/OFQ inhibits learning and memory abilities in mice. Here, we investigated whether the endogenous peptide also regulated emotional responses at the level of the hippocampus. Bilateral infusions of the selective NOP receptor antagonist, UFP-101 (1-3 nmol/side), into the dorsal hippocampus produced antidepressant-like effects in the mouse forced swim and tail suspension tests comparable with those obtained with the prototypical antidepressant, fluoxetine (10-30 mg/kg, intraperitoneal). In the light-dark test, neither UFP-101 (1-3 nmol/side) nor N/OFQ peptide (1-3 nmol/side) modified anxiety measures when injected at behaviorally active doses in the dorsal hippocampus. These findings show a clear dissociation in the involvement of hippocampal N/OFQ system in anxiety- and despair-related behaviors. We conclude that the dorsal hippocampus is a brain region in which there is an important N/OFQ modulation of mnemonic processes and adaptive emotional responses associated to despair states.

Topics: Analysis of Variance; Animals; Behavior, Animal; Dark Adaptation; Depression; Disease Models, Animal; Hindlimb Suspension; Hippocampus; Imidazoles; Male; Mice; Mice, Inbred C57BL; Nociceptin; Opioid Peptides; Spiro Compounds; Swimming

Increasing evidence suggests that defensive escape behavior in Lister-hooded (LH) rats induced by ultrasound application may be an animal model of panic disorder.. The objectives of this study were to further explore the face and construct validity of ultrasound-induced escape behavior by characterizing the autonomic and neuroendocrine response to ultrasound, and to examine the underlying neuronal structures by comparing the effects of the anxiolytic with panicolytic properties, diazepam, with a preclinical anxiolytic without panicolytic-like activity, the NOP agonist Ro 64-6198.. LH rats were implanted with telemetry transmitters to monitor heart rate and core body temperature before, during, and after ultrasound application. Blood samples were taken after ultrasound application for corticosterone analysis. Ultrasound-induced c-Fos expression was measured in different periaqueductal gray (PAG) and amygdala subregions after treatment with diazepam or Ro 64-6198.. Ultrasound application increased heart rate and body temperature, but did not alter plasma corticosterone levels. Ultrasound application increased c-Fos expression in the dorsal and dorsolateral PAG (dPAG, dlPAG) and amygdaloid subregions. Diazepam, but not Ro 64-6198, reduced c-Fos expression in the dPAG/dlPAG, while Ro 64-6198, but not diazepam, reduced c-Fos expression in the central amygdala.. Similar to human panic attacks, ultrasound application to LH rats activated the autonomic, but not the neuroendocrine, stress system. Also, like in humans, the current data confirm and extend that the dPAG/dlPAG plays a key role in ultrasound-induced escape behavior. These observations suggest that ultrasound-induced escape behaviors in LH rats have face and construct validity for panic disorders.

Topics: Amygdala; Animals; Anti-Anxiety Agents; Body Temperature; Diazepam; Disease Models, Animal; Escape Reaction; Gene Expression Regulation; Heart Rate; Imidazoles; Male; Panic Disorder; Proto-Oncogene Proteins c-fos; Rats; Spiro Compounds; Telemetry; Ultrasonics

The nociceptin system seems to be involved in modulation of acute nociceptive stimulation and in chronic pain processes, e.g. inflammation and neuropathy. In the present study, we examined the analgesic effect of a new opioid receptor-like (ORL1) receptor agonist, Ro64-6198, and compared it with the effect of endogenous ORL1 receptor agonist, nociceptin/orphanin FQ (N/OFQ), in a model of neuropathic pain in the rat. Ro64-6198 was injected intrathecaly (i.t.), intraplantarly (i.pl.) and subcutaneously (s.c.), and responses of neuropathic rats were measured in tactile (von Frey) and thermal (cold water) allodynia tests. Ro64-6198 did not change the pain threshold in naive animals, but exhibited antiallodynic activity in neuropathic rats. This effect was observed after i.t. and i.pl. but not after s.c. administration. Moreover, the observed antiallodynic potency of Ro64-6198 was weaker in comparison with N/OFQ after i.t. administration of either agonist, but almost equal after i.pl. injection. Selective antagonists of the ORL1 receptor, [Phe1Psi(CH2-NH)Gly2]NC(1-13)NH2 (PhePsi) and [N-Phe1]-NC(1-13)NH2 (NPhe), inhibited the antiallodynic actions of Ro64-6198 which indicated that the spinal and peripheral antinociceptive effects were mediated by ORL1 receptors. Therefore, besides spinal, also peripheral ORL1 receptors may be targeted by drugs designed for the long-term treatment of chronic pain.

Topics: Analysis of Variance; Animals; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Administration Routes; Drug Interactions; Hyperalgesia; Imidazoles; Male; Neuralgia; Nociceptin Receptor; Opioid Peptides; Pain Measurement; Pain Threshold; Peptide Fragments; Rats; Rats, Wistar; Reaction Time; Receptors, Opioid; Sciatic Neuropathy; Spinal Cord; Spiro Compounds; Time Factors