nocistatin and Inflammation

While acute pain has a fundamental role to operate a protective system, chronic pain associated with inflammation and nerve injury often outlasts its biological usefulness. Therefore, there has recently been great interest in the neurochemical mechanisms of hyperalgesia to noxious stimuli and tactile pain (allodynia) to innocuous stimuli with a hope to relieve persistent, intractable pain. Over several decades non-steroidal anti-inflammatory drugs and opioids have been employed for clinical management of pain. The introduction of molecular biology to pain research has enabled us to describe the mechanism of pain at the molecular level and to develop analgesics with selectivity for targets and with less adverse effects. This review focuses on current knowledge concerning mechanisms and pathways for pain induced by prostaglandins and their interactions with novel neuropeptides nociceptin/orphanin FQ and nocistatin derived from the same opioid precursor protein.

Topics: Analgesics; Animals; Anti-Inflammatory Agents, Non-Steroidal; Arachidonic Acids; Brain; Cattle; Cyclooxygenase 1; Cyclooxygenase Inhibitors; Drug Synergism; Glutamic Acid; Humans; Hyperalgesia; Inflammation; Isoenzymes; Membrane Proteins; Mice; Mice, Knockout; Models, Animal; Models, Biological; Neuralgia; Neuronal Plasticity; Nitric Oxide; Nociceptin; Nociceptors; Opioid Peptides; Pain; Peripheral Nerves; Prostaglandin-Endoperoxide Synthases; Prostaglandins; Protein Precursors; Rats; Spinal Cord; Thromboxane-A Synthase

Chronic pain associated with inflammation is an important clinical problem, and the underlying mechanisms remain poorly understood. 4-Nitrophenylphosphatase domain and nonneuronal SNAP25-like protein homolog (NIPSNAP) 1, an interacting protein with neuropeptide nocistatin, is implicated in the inhibition of tactile pain allodynia. Although nocistatin inhibits some inflammatory pain responses, whether NIPSNAP1 affects inflammatory pain appears to be unclear. Here, we examined the nociceptive behavioral response of NIPSNAP1-deficient mice and the expression of NIPSNAP1 following peripheral inflammation to determine the contribution of NIPSNAP1 to inflammatory pain.. Nociceptive behavioral response increased in phase II of the formalin test, particularly during the later stage (26-50 min) in NIPSNAP1-deficient mice, although the response during phase I (0-15 min) was not significantly different between the deficient and wild-type mice. Moreover, phosphorylation of extracellular signal-related kinase was enhanced in the spinal dorsal horn of the deficient mice. The prolonged inflammatory pain induced by carrageenan and complete Freund's adjuvant was exacerbated in NIPSNAP1-deficient mice. NIPSNAP1 mRNA was expressed in small- and medium-sized neurons of the dorsal root ganglion and motor neurons of the spinal cord. In the formalin test, NIPSNAP1 mRNA was slightly increased in dorsal root ganglion but not in the spinal cord. In contrast, NIPSNAP1 mRNA levels in dorsal root ganglion were significantly decreased during 24-48 h after carrageenan injection. Prostaglandin E2, a major mediator of inflammation, stimulated NIPSNAP1 mRNA expression via the cAMP-protein kinase A signaling pathway in isolated dorsal root ganglion cells.. These results suggest that changes in NIPSNAP1 expression may contribute to the pathogenesis of inflammatory pain.

Topics: Animals; Cyclooxygenase Inhibitors; Dinoprostone; Formaldehyde; Ganglia, Spinal; Inflammation; Intercellular Signaling Peptides and Proteins; Membrane Proteins; Mice; Neuropeptides; Opioid Peptides; Pain; Proteins; RNA, Messenger

Nocistatin (NST) and Nociceptin/Orphanin FQ (N/OFQ) are derived from the same precursor protein, pre-proN/OFQ, and exert opposite effects on the modulation of pain signals. However, the role of the peripheral N/OFQ and the NOP receptor, which is located at the endings of sensory nerves, in inflammatory pain was not ascertained. NST administered intrathecally (i.t.) prevented the nociceptive effects induced by i.t. N/OFQ and PGE₂. Moreover an up regulation of N/OFQ was shown in the rat in response to peripheral inflammation. Here, we investigated the effects of intraplantar (i.pl.) administration of functional N/OFQ and NOP receptor antagonists in a rat model of inflammatory pain. Our findings showed that i.pl. injection of (±)-J 113397, a selective antagonist of the NOP receptor, and NST, the functional N/OFQ antagonist, prior to carrageenan significantly reduced the paw allodynic and thermal hyperalgesic threshold induced by the inflammatory agent. The resulting antiallodynic and antihyperalgesic effects by co-administering NST and (±)-J 113397 prior to carrageenan were markedly enhanced, and the basal latencies were restored. Thus, it is likely that the peripheral N/OFQ/NOP receptor system contributes to the abnormal pain sensitivity in an inflammatory state.

Topics: Analgesics; Analgesics, Opioid; Animals; Behavior, Animal; Benzimidazoles; Disease Models, Animal; Drug Therapy, Combination; Hyperalgesia; Inflammation; Injections, Subcutaneous; Male; Metatarsus; Narcotic Antagonists; Nociceptin; Nociceptin Receptor; Nociceptive Pain; Opioid Peptides; Pain Threshold; Peripheral Nerves; Piperidines; Random Allocation; Rats; Rats, Sprague-Dawley; Receptors, Opioid; Signal Transduction

Nocistatin is a biologically active peptide derived from prepronociceptin, and its intrathecal administration has been reported to reduce nociceptin- or prostaglandin E2-induced hyperalgesia and allodynia in mice. In this study, we investigated the effects of intracerebroventricular (i.c.v.) administration of nocistatin on the inflammatory hyperalgesia induced by hindlimb intraplantar injection of carrageenan/kaolin in the rat paw-pressure test. Intracerebroventricular administration of nocistatin (0.5-50 pmol/rat) dose-dependently reduced carrageenan/kaolin-induced hyperalgesia, which peaked at 15-30 m. However, i.c.v. administration of nocistatin (50 pmol/rat) had no effect on the nociceptive threshold of non-inflamed rats. These results indicate that nocistatin has anti-hyperalgesic effects on the inflammatory hyperalgesia induced by carrageenan/kaolin at the supraspinal level.

Topics: Animals; Carrageenan; Drug Evaluation, Preclinical; Hindlimb; Hyperalgesia; Inflammation; Injections, Intraventricular; Kaolin; Male; Opioid Peptides; Rats; Rats, Sprague-Dawley