piperidines and Hyperesthesia

The efficacy and tolerability of naratriptan tablets (2.5 mg, 1 mg, and 0.25 mg) compared with placebo in the acute treatment of migraine were evaluated in a randomized, double-blind, four-period crossover study. Five hundred eighty-six assessable patients received naratriptan 2.5 mg, 595 received 1 mg, 591 received 0.25 mg, 602 received placebo. Headache relief (moderate or severe pain reduced to mild or none) 4 hours postdose was reported in 68% of patients after treatment with naratriptan 2.5 mg compared with 57% after 1 mg, 39% after 0.25 mg, and 33% after placebo (p < 0.001 naratriptan 2.5 mg and 1 mg versus placebo and 1 mg and 2.5 mg versus 0.25 mg). Headache relief was maintained 8, 12, and 24 hours postdose with no use of rescue medication or a second dose of study medication by significantly (p < 0.001) greater percentages of patients after treatment with naratriptan 2.5 mg or 1 mg compared with naratriptan 0.25 mg or placebo. Naratriptan was also more effective than placebo in reducing clinical disability and the incidences of nausea, photophobia, and phonophobia. The overall incidence of adverse events and the incidences of specific adverse events did not differ in the naratriptan groups compared with placebo. No clinically relevant changes in ECG, blood pressure, or laboratory findings were reported. These data demonstrate that naratriptan is effective and well tolerated for the acute treatment of migraine. The 2.5-mg dose was associated with superior efficacy, whereas its adverse event profile was similar to that of placebo.

Topics: Adolescent; Adult; Aged; Cross-Over Studies; Double-Blind Method; Female; Gastrointestinal Diseases; Humans; Hyperesthesia; Indoles; Male; Middle Aged; Migraine Disorders; Piperidines; Recurrence; Serotonin Receptor Agonists; Treatment Outcome; Tryptamines

This study was performed to determine whether spinal cholinergic systems mediate the relieving effects of electroacupuncture (EA) on cold and warm allodynia in a rat model of neuropathic pain. For neuropathic surgery, the right superior caudal trunk was resected at the level between the S1 and S2 spinal nerves innervating the tail. Two weeks after the injury, the intrathecal (i.t.) catheter was implanted. Five days after the catheterization, the rats were injected with atropine (non-selective muscarinic antagonist, 30 microg), mecamylamine (non-selective nicotinic antagonist, 50 microg), pirenzepine (M(1) muscarinic antagonist, 10 microg), methoctramine (M(2) antagonist, 10 microg) or 4-diphenylacetoxy-N-methylpiperidine methiodide (4-DAMP) (M(3) antagonist, 10 microg). Ten minutes after the injection, EA was applied to the ST36 acupoint for 30 min. The cold and warm allodynia were assessed by the tail immersion test [i.e., immersing the tail in cold (4 degrees C) or warm (40 degrees C) water and measuring the latency of an abrupt tail movement] before and after the treatments. The i.t. atropine, but not mecamylamine, blocked the relieving effects of EA on cold and warm allodynia. Furthermore, i.t. pirenzepine attenuated the antiallodynic effects of EA, whereas methoctramine and 4-DAMP did not. These results suggest that spinal muscarinic receptors, especially M(1) subtype, mediate the EA-induced antiallodynia in neuropathic rats.

Topics: Animals; Atropine; Cholinergic Agents; Cholinergic Fibers; Cold Temperature; Diamines; Disease Models, Animal; Electroacupuncture; Hot Temperature; Hyperesthesia; Male; Mecamylamine; Neuralgia; Pain Threshold; Piperidines; Pirenzepine; Rats; Rats, Sprague-Dawley; Receptor, Muscarinic M1; Spinal Nerves

Spinal cord injury (SCI) pain exhibits many symptoms associated with peripheral neuropathic pain, including increased tactile hypersensitivity. One novel approach to ameliorate SCI pain is the use of cannabinoid (CB) ligands. The current study evaluated the efficacy of the nonselective CB receptor agonist WIN 55,212-2 on tactile hypersensitivity in rats following a brief compression to the thoracic spinal cord. The withdrawal thresholds of the hind paws following SCI were significantly decreased, indicating tactile hypersensitivity. Systemic injection of WIN 55,212-2 increased withdrawal thresholds in a dose-dependent manner. Pretreatment with the CB(1) receptor subtype-selective antagonist AM 251 completely abolished the antinociceptive effect of WIN 55,212-2 whereas pretreatment with the CB(2) receptor subtype-selective antagonist AM 630 did not alter the antinociceptive effect of WIN 55,212-2. These data indicate that a CB(1)-selective agonist may be novel therapeutic treatment for clinical SCI pain.

Topics: Analgesics; Animals; Benzoxazines; Cannabinoid Receptor Agonists; Hindlimb; Hyperesthesia; Male; Morpholines; Naphthalenes; Nociceptors; Pain Threshold; Physical Stimulation; Piperidines; Pyrazoles; Rats; Rats, Sprague-Dawley; Receptor, Cannabinoid, CB1; Spinal Cord Compression; Spinal Cord Injuries; Thoracic Vertebrae

Trigeminal neuralgia is a disorder of paroxysmal and severely disabling facial pain and continues to be a real therapeutic challenge. At present there are few effective drugs. Here we have evaluated the effects of the synthetic cannabinoid WIN 55,212-2 on mechanical allodynia and thermal hyperalgesia in a rat model of trigeminal neuropathic pain produced by a chronic constriction injury (CCI) of the infraorbital branch of the trigeminal nerve (ION). Relative to sham operation controls, rats with the CCI-ION consistently displayed hyperresponsiveness to von Frey filament and heat stimulation of the vibrissal pad. Both mechanical allodynia and thermal hyperalgesia are seen both ipsilateral and contralateral to the side of nerve injury, but is significantly more severe ipsilaterally. Administration of WIN 55,212-2 (0.3-5 mg/kg i.p.) dose-dependently increased the mechanical and heat withdrawal thresholds. WIN 55,212-2 (0.3-3 mg/kg i.p.) produced no significant motor deficits in animals using the rotarod test. The effect of WIN 55,212-2 was mimicked by cannabinoid CB1 receptor agonist HU 210 and was antagonized by CB1 receptor antagonist AM 251, but not by CB2 receptor antagonist AM 630 or vanilloid receptor 1 antagonist capsazepine, suggesting the involvement of CB1 receptors. CCI-ION also induced a time-dependent upregulation of CB1 receptors primarily within the ipsilateral superficial laminae of the trigeminal caudal nucleus revealed by both Western blot and immunohistochemistry. Taken together, these results suggest that cannabinoids may be a useful therapeutic approach for the clinical management of trigeminal neuropathic pain disorders.

Topics: Analgesics; Analysis of Variance; Animals; Benzoxazines; Cannabinoids; Disease Models, Animal; Dose-Response Relationship, Drug; Functional Laterality; Hyperalgesia; Hyperesthesia; Indoles; Male; Morpholines; Naphthalenes; Pain Measurement; Pain Threshold; Piperidines; Pyrazoles; Rats; Rats, Sprague-Dawley; Reaction Time; Receptor, Cannabinoid, CB1; Time Factors; Trigeminal Nerve Diseases

The ability of cannabinoids to suppress mechanical hypersensitivity (mechanical allodynia) induced by treatment with the chemotherapeutic agent vincristine was evaluated in rats. Sites of action were subsequently identified.. Mechanical hypersensitivity developed over the course of ten daily injections of vincristine relative to groups receiving saline at the same times. Effects of the CB1/CB2 receptor agonist WIN55,212-2, the receptor-inactive enantiomer WIN55,212-3, the CB2-selective agonist (R,S)-AM1241, the opiate agonist morphine and vehicle on chemotherapy-induced neuropathy were evaluated. WIN55,212-2 was administered intrathecally (i.t.) or locally in the hindpaw to identify sites of action. Pharmacological specificity was established using competitive antagonists for CB1 (SR141716) or CB2 receptors (SR144528).. Systemic administration of WIN55,212-2, but not WIN55,212-3, suppressed vincristine-evoked mechanical allodynia. A leftward shift in the dose-response curve was observed following WIN55,212-2 relative to morphine treatment. The CB1 (SR141716) and CB2 (SR144528) antagonists blocked the anti-allodynic effects of WIN55,212-2. (R,S)-AM1241 suppressed vincristine-induced mechanical hypersensitivity through a CB2 mechanism. Both cannabinoid agonists suppressed vincristine-induced mechanical hypersensitivity without inducing catalepsy. Spinal sites of action are implicated in cannabinoid modulation of chemotherapy-induced neuropathy. WIN55,212-2, but not WIN55,212-3, administered i.t. suppressed vincristine-evoked mechanical hypersensitivity at doses that were inactive following local hindpaw administration. Spinal coadministration of both the CB1 and CB2 antagonists blocked the anti-allodynic effects of WIN55,212-2.. Cannabinoids suppress the maintenance of vincristine-induced mechanical allodynia through activation of CB1 and CB2 receptors. These anti-allodynic effects are mediated, at least in part, at the level of the spinal cord.

Topics: Animals; Benzoxazines; Body Weight; Camphanes; Cannabinoids; Catalepsy; Dose-Response Relationship, Drug; Hindlimb; Hyperesthesia; Injections, Intraperitoneal; Injections, Spinal; Male; Morphine; Morpholines; Naphthalenes; Neuralgia; Pain Measurement; Pain Threshold; Physical Stimulation; Piperidines; Pyrazoles; Rats; Rats, Sprague-Dawley; Receptor, Cannabinoid, CB1; Receptor, Cannabinoid, CB2; Rimonabant; Thermosensing; Vincristine

New strategies have recently been developed where infusion of neurotrophic factors into the brain can rescue different neuronal populations. However, negative side effects have been observed in clinical trials infusing nerve growth factor (NGF) into the lateral ventricle in man, namely pain. Little is known about pain behavior in animals after intracerebroventricular (i.c.v.) neurotrophic injections. Thus, we have examined the effects of i.c.v. infusion of NGF for 2 weeks on the behavioral response of rats to mechanical, cold and heat stimulation. Seven micrograms/day of NGF elicited a significant decrease in vocalization threshold to mechanical stimulation and a significantly increased response to cold and heat stimuli as compared with control. The concentration of NGF in cerebrospinal fluid (CSF) was significantly increased as compared with non-allodynic rats. The enhanced responses to mechanical and heat, but not to cold, stimulation were significantly reduced by CP-99994, a selective antagonist to tachykinin NK-1 receptors. When NGF was infused into the brain parenchyma (striatum, cortex and septum) no allodynic nor hyperalgesic responses could be detected. These results indicate that in rats i.c.v. but not intraparenchymal infusion of NGF induce mechanical and cold allodynia as well as heat hyperalgesia, which is mediated, at least in part, by activation of NK-1 receptors.

Topics: Animals; Behavior, Animal; Brain; Cold Temperature; Hot Temperature; Hyperesthesia; Injections, Intraventricular; Male; Nerve Growth Factor; Neurokinin-1 Receptor Antagonists; Pain; Pain Threshold; Physical Stimulation; Piperidines; Rats; Rats, Sprague-Dawley; Reference Values; Vocalization, Animal

The effects of ethylketazocine (EKC) administered intraperitoneally and the nicotinic ligands (-)- and (+)-nicotine, (-)-cytisine, (-)-lobeline, and (+)-2-methylpiperidine administered into the 4th ventricle on the latency of the thermally evoked withdrawal reflex of the decerebrate rat were investigated. EKC administered intraperitoneally produced both hyperalgesia and analgesia. (-)-Nicotine administered into the 4th ventricle produced a biphasic dose related effect on the latency of the withdrawal reflex; low doses produced a dose related analgesia while higher doses produced hyperalgesia. (-)-Cytisine and (-)-lobeline administered into the 4th ventricle produced biphasic effects. (+)-2-Methylpiperidine administered into the 4th ventricle produced a significant degree of hyperalgesia. Both the analgesic and hyperalgesic effects of (-)-nicotine were antagonized by mecamylamine (1 mg/kg) and naltrexone (5 mg/kg). The hyperalgesic action of (+)-2-methylpiperidine was antagonized by naltrexone but not by mecamylamine. These observations suggest that there are both medullary opioidergic and nicotinic cholinergic mechanisms for modulating both analgesic and hyperalgesic processes and that nicotinic ligands have multiple mechanisms of action in the brain.

Topics: Analgesics, Opioid; Animals; Cyclazocine; Cystine; Decerebrate State; Endorphins; Ethylketocyclazocine; Female; Hyperalgesia; Hyperesthesia; Lobeline; Medulla Oblongata; Nicotine; Piperidines; Rats; Rats, Inbred Strains

Topics: 1-Propanol; Adult; Benzene Derivatives; Dyspareunia; Female; Humans; Hyperesthesia; Mesylates; Piperidines; Vaginal Diseases

Topics: Humans; Hyperesthesia; Maleates; Nystagmus, Pathologic; Perhexiline; Piperidines; Postural Balance; Vertigo; Vestibular Function Tests

Topics: Amphetamine; Amphetamines; Biphenyl Compounds; Chemical Phenomena; Chemistry; Dioxolanes; Heterocyclic Compounds; Hexobarbital; Hot Temperature; Hyperesthesia; Mice; Morphine; Pharmacology; Piperidines; Quinones; Reaction Time; Research; Reserpine; Sleep