Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0423716 (Neuropathic pain)
 1,417 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Neuropathic pain (NPP) due to sensory nerve injury is, in part, the result of peripheral sensitization leading to a long-lasting increase in synaptic plasticity in the spinal dorsal horn. Thus, activation of GABA-mediated inhibitory inputs from sensory neurons could be beneficial in the alleviation of NPP symptoms. Dorsal root ganglia (DRG) conduct painful stimulation from the periphery to the spinal cord. Long-lasting down-regulation in GABA tone or sensitivity in DRG neurons has been reported in animals with neuropathy. To determine the function of GABA in DRG in the development of NPP, we examined how the acute pharmacological GABA(A)-receptor modulation of L5 DRG in vivo affects the development of NPP in rats with crush injury to the sciatic nerve. Direct application of muscimol and gaboxadol, GABA(A) agonists, to L5 DRG immediately after injury induced dose-dependent alleviation, whereas bicuculline and picrotoxin, GABA(A) antagonists, worsened NPP postaxonal injury. The pain-alleviating effects of muscimol and gaboxadol were blocked by bicuculline. Muscimol, applied at the time of injury, caused complete and long-lasting abolishment of NPP development. However, when muscimol was applied after NPP had already developed, its pain-alleviating effect, although significant, was short-lived. Using a fluorescent tracer, sodium fluorescein, we confirmed that local DRG application results in minimal spread into the corresponding dorsal horn of the ipsilateral spinal cord. GABA(A) receptors in DRG are important in the development of NPP after peripheral nerve injury, making timely exogenous GABAergic manipulation at the DRG level a potentially useful therapeutic modality.
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PMID:GABAA receptor modulation in dorsal root ganglia in vivo affects chronic pain after nerve injury. 1855 16

Neuropathic pain remains a prevalent clinical problem because it is often poorly responsive to the currently used analgesics, thus it is crucial the identification of new potential targets and drugs. Recent evidence indicated that microglial cells in the spinal cord are critically involved in the development and maintenance of neuropathic pain, with a pivotal role of toll-like receptor 4 (TLR4). Binding of an endogenous ligand to TLR4 might be considered an important step in the regulation of microglia activity in pain facilitation, suggesting that a mechanism aimed to inhibit such a binding could be effective against neuropathic pain. We have synthesized new ligands to TLR4 with antagonistic activity. In the present work we evaluated the efficacy of the most potent TLR4 antagonist synthesized by us (FP-1), administered in mice with painful neuropathy. The repeated treatment of neuropathic mice with FP-1 (5-10 mg/kg, i.p.) evoked a relief of both thermal hyperalgesia and mechanical allodynia, whereas the administration of the highest dose to TLR4 knockout neuropathic mice revealed that in the absence of TLR4 receptor, the compound lost its efficacy. As consequence of TLR4 binding, the repeated treatment with FP-1 prevented the activation of the transcription factor NF-kB and the TNFalpha overproduction in the spinal cord. Together, our findings support the previous evidence indicative for a contribution of glial TLR4 to the initiation of neuropathic pain, suggest it as potential innovative target to treat this debilitating disease, and propose FP-1 as lead compound for the development of new effective drugs.
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PMID:Glial TLR4 receptor as new target to treat neuropathic pain: efficacy of a new receptor antagonist in a model of peripheral nerve injury in mice. 1861 68

Neuropathic pain is commonly associated with affective disorders such as anxiety and depression. We have previously characterised a rodent model of HIV, anti-retroviral-associated neuropathy in which rats develop hypersensitivity to a punctate mechanical stimulus and display anxiety-like behaviour in the open field paradigm. To assess the potential of this behavioural paradigm for the assessment of pain related co-morbidities in rodent models of pain, here we test the sensitivity of this anxiety-like behaviour to the analgesic agents gabapentin and morphine in comparison to the known anxiolytic drug diazepam. We found that gabapentin (30 mg/kg, i.p.) and morphine (2.5 mg/kg, i.p.), which reduce mechanical hypersensitivity in these rats, significantly reduces measures of thigmotaxis in the open field. The effect of gabapentin and morphine did not differ significantly from diazepam (1 mg/kg, i.p.). This study highlights the potential use of this rodent model and behavioural paradigm in the validation of the affective component of novel analgesic pharmacological targets and elucidation of underlying pathophysiological mechanisms.
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PMID:Anxiety-like behaviour is attenuated by gabapentin, morphine and diazepam in a rodent model of HIV anti-retroviral-associated neuropathic pain. 1892 76

Treatment of neuropathic pain is the primary focus of management for many patients with painful peripheral neuropathies. Antidepressants and anticonvulsants are the two medication classes most widely studied and represent first-line agents in the management of neuropathic pain. The number of pharmacologic agents and interventional procedures that have shown effectiveness in the treatment of neuropathic pain continues to expand. Pain management should begin with a concerted effort to identify the etiology of the neuropathy, because directed therapy can help alleviate the symptoms. When initiating pharmacotherapy for neuropathic pain, one must individualize treatment and choose an agent that is likely to be tolerated, because adverse events are common for many of these agents. Neuropathic pain management remains challenging because of heterogeneous responses between individuals and the fact that pain relief is rarely complete. However, monotherapy with a well-chosen agent or rational polypharmacy that combines medications with different mechanisms of action will benefit a majority of patients with neuropathic pain.
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PMID:Treatment of painful peripheral neuropathy. 1907 90

Neuropathic pain is a disease caused by a lesion or dysfunction of the nervous system. Antidepressants or anticonvulsants are presently the best available treatments. The mechanism by which antidepressants relieve neuropathic pain remains poorly understood. Using pharmacological and transgenic approaches in mice, we evaluated adrenergic receptor (AR) implication in the action of the tricyclic antidepressant desipramine, the noradrenaline and serotonin reuptake inhibitor venlafaxine, and the noradrenaline reuptake inhibitor reboxetine. Neuropathy was induced by cuff insertion around the sciatic nerve. We showed that chronic antidepressant treatment suppressed cuff-induced allodynia in wild-type mice but not in beta(2)-AR deficient mice, and/or that this antiallodynic action was blocked by intraperitoneal or intrathecal injection of the beta(2)-AR antagonist ICI 118,551 but not by the alpha(2)-AR antagonist yohimbine. We also showed that the anticonvulsant gabapentin was still effective in beta(2)-AR deficient mice. Our results demonstrate that beta(2)-ARs are essential for the antiallodynic action of antidepressant drugs.
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PMID:Beta2-adrenoceptors are essential for desipramine, venlafaxine or reboxetine action in neuropathic pain. 1908 64

The analgesic effects of leukocyte-derived opioids have been exclusively demonstrated for somatic inflammatory pain, for example, the pain associated with surgery and arthritis. Neuropathic pain results from injury to nerves, is often resistant to current treatments, and can seriously impair a patient's quality of life. Although it has been recognized that neuronal damage can involve inflammation, it is generally assumed that immune cells act predominately as generators of neuropathic pain. However, in this study we have demonstrated that leukocytes containing opioids are essential regulators of pain in a mouse model of neuropathy. About 30%-40% of immune cells that accumulated at injured nerves expressed opioid peptides such as beta-endorphin, Met-enkephalin, and dynorphin A. Selective stimulation of these cells by local application of corticotropin-releasing factor led to opioid peptide-mediated activation of opioid receptors in damaged nerves. This ultimately abolished tactile allodynia, a highly debilitating heightened response to normally innocuous mechanical stimuli, which is symptomatic of neuropathy. Our findings suggest that selective targeting of opioid-containing immune cells promotes endogenous pain control and offers novel opportunities for management of painful neuropathies.
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PMID:Immune cell-derived opioids protect against neuropathic pain in mice. 1913 63

Neuropathic pain results from damage to the peripheral sensory nervous system, which may have a number of causes. The calcium channel subunit alpha(2)delta-1 is upregulated in dorsal root ganglion (DRG) neurons in several animal models of neuropathic pain, and this is causally related to the onset of allodynia, in which a non-noxious stimulus becomes painful. The therapeutic drugs gabapentin and pregabalin (PGB), which are both alpha(2)delta ligands, have antiallodynic effects, but their mechanism of action has remained elusive. To investigate this, we used an in vivo rat model of neuropathy, unilateral lumbar spinal nerve ligation (SNL), to characterize the distribution of alpha(2)delta-1 in DRG neurons, both at the light- and electron-microscopic level. We found that, on the side of the ligation, alpha(2)delta-1 was increased in the endoplasmic reticulum of DRG somata, in intracellular vesicular structures within their axons, and in the plasma membrane of their presynaptic terminals in superficial layers of the dorsal horn. Chronic PGB treatment of SNL animals, at a dose that alleviated allodynia, markedly reduced the elevation of alpha(2)delta-1 in the spinal cord and ascending axon tracts. In contrast, it had no effect on the upregulation of alpha(2)delta-1 mRNA and protein in DRGs. In vitro, PGB reduced plasma membrane expression of alpha(2)delta-1 without affecting endocytosis. We conclude that the antiallodynic effect of PGB in vivo is associated with impaired anterograde trafficking of alpha(2)delta-1, resulting in its decrease in presynaptic terminals, which would reduce neurotransmitter release and spinal sensitization, an important factor in the maintenance of neuropathic pain.
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PMID:The increased trafficking of the calcium channel subunit alpha2delta-1 to presynaptic terminals in neuropathic pain is inhibited by the alpha2delta ligand pregabalin. 1933 3

The market for pain treatment is a major segment of nervous system pathologies. Despite this dynamism, the management of some pain conditions remains a clinical challenge. Neuropathic pain arises as a direct consequence of a lesion or disease affecting the somatosensory system. It is generally a chronic and disabling condition which is difficult to treat. Antidepressant drugs are recommended as one of the first line treatments, but they display noticeable side effects and are not effective on all patients. Using a murine model of neuropathy, we demonstrated that the stimulation of beta2-adrenergic receptors (beta2-AR) is not only necessary for antidepressant drugs to exert their antiallodynic action but that it is in fact sufficient to alleviate neuropathic allodynia. Chronic, but not acute, treatment with beta-mimetics such as terbutaline, salbutamol, fenoterol, salmeterol, ritodrine, isoprenaline (isoproterenol), metaproterenol (orciprenaline), procaterol, formoterol, clenbuterol or bambuterol, relieves allodynia. Agonists of beta2-ARs, and more generally any molecule stimulating beta2-ARs such as beta-mimetics, are thus proposed as potential new treatments for neuropathic pain. Clinical studies are now in preparation to confirm this potential in patients with neuropathic pain. This article reviews the findings leading to propose beta-mimetics for neuropathic pain treatment and other recent patents on the topic.
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PMID:From antidepressant drugs to beta-mimetics: preclinical insights on potential new treatments for neuropathic pain. 1953 57

Neuropathic pain is an increasingly common problem facing the cancer patient. Painful neuropathy can come from various sources and significantly impact quality of life. The most commonly observed scenario is paraesthesia and dysesthesia as a result of toxic effects of chemotherapies on the distal peripheral nerves. Neuropathic pain should be addressed ideally with the help of a neuro-oncologist, and it usually can be successfully treated with a variety of agents, including atypical analgesics such as antidepressants, newer drugs with analgesic benefit, and opioids for more refractory cases. Direct and indirect effects of the primary neoplasm need to be considered in the etiology of specific syndromes of mononeuropathies and plexopathies.
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PMID:Assessment of neuropathic pain in cancer patients. 1958 91

Neuropathic pain is one of the worst painful symptoms in clinic. It contains nerve-injured neuropathy, diabetic neuropathy, chronic inflammatory pain, cancer pain, and postherpes pain, and is characterized by a tactile allodynia and hyperalgesia. Neuropathic pain, especially the nerve-injured neuropathy, the diabetic neuropathy, and the cancer pain, is opioid resistant pain. Since the downregulation of mu-opioid receptors is observed in dorsal spinal cord, morphine and fentanyl could not provide marked antihyperalgesic/antiallodynic effects in the course neuropathic pain states. The downregulation of mu-opioid receptors is suggested to be mediated through the activation of NMDA receptors. Moreover, at the neuropathic pain states, the increased expression of voltage-dependent Na+ channels and Ca2+ channels are observed. Based on the above information concerned with the pathophysiology of neural changes in neuropathic pain states, new drug treatments for neuropathic pain, using ketamine, methadone, and gabapentin, have been developed. These drugs show remarkable effectiveness against hyperalgesia and allodynia during neuropathic pain states. Oxycodone is a mu-opioid receptor agonist, which has different pharmacological profiles with morphine. The remarkable effectiveness of oxycodone for neuropathic pain provides the possibility that mu-opioid receptor agonists, which have different pharmacological profile with morphine, can be used for the management of neuropathic pain.
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PMID:New therapy for neuropathic pain. 1960 75


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