Articles: neuropathic-pain.
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Neurobiology of disease · Oct 2014
Central P2Y12 receptor blockade alleviates inflammatory and neuropathic pain and cytokine production in rodents.
In this study the role of P2Y12 receptors (P2Y12R) was explored in rodent models of inflammatory and neuropathic pain and in acute thermal nociception. In correlation with their activity to block the recombinant human P2Y12R, the majority of P2Y12R antagonists alleviated mechanical hyperalgesia dose-dependently, following intraplantar CFA injection, and after partial ligation of the sciatic nerve in rats. They also caused an increase in thermal nociceptive threshold in the hot plate test. ⋯ Genetic deletion of the P2Y12R in mice reproduced the effect of P2Y12R antagonists on mechanical hyperalgesia in inflammatory and neuropathic pain models, on acute thermal nociception and on the induction of spinal IL-1β. Here we report the robust involvement of the P2Y12R in inflammatory pain. The anti-hyperalgesic effect of P2Y12R antagonism could be mediated by the inhibition of both central and peripheral cytokine production and involves α7-receptor mediated efferent pathways.
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Current data suggest that transcranial magnetic stimulation (TMS) has the potential to be an effective and complimentary treatment modality for patients with chronic neuropathic pain syndromes. The success of TMS for pain relief depends on the parameters of the stimulation delivered, the location of neural target, and duration of treatment. TMS can be used to excite or inhibit underlying neural tissue that depends on long-term potentiation and long-term depression, respectively. Long-term randomized controlled studies are warranted to establish the efficacy of repetitive TMS in patients with various chronic pain syndromes.
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Spinal cord stimulation (SCS) is well accepted for the treatment of chronic pain since its beginning in 1967. As its use continues to enter into the chronic pain treatment algorithm earlier, conscience patient selection and durability of the therapy are clearly clinically relevant. To improve treatment efficacy, consensus statements and guidelines were developed. ⋯ The current available guideline statements have clear deficiencies in either scope of coverage, evidence synthesis, or lack of transparency of funding. Improved evidence and best practice/guideline assessment may improve patient outcomes and accessibility to these important modalities. Further prospective comparator randomized data are required to not only provide data of clinical and cost-effectiveness in other indications but also to better describe the position of neurostimulation application within the disease management pathway. Therein cases where there appears to be sufficient evidence and consensus, every effort should be made to secure access to these effective therapies. Importantly, each guideline only has a useful clinical half-life, if not updated. This should be acknowledged by both clinicians and third-party payers. Based on these deficiencies, the International Neuromodulation Society recommended the creation of a consensus conference to examine the appropriate use of neurostimulation for pain and ischemic disease.
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The dorsal root ganglion (DRG), in the not too distant past, had been thought of as a passive organ not involved in the development of abnormal aberrent neuropathic pain (NP), but merely metabolically "supporting" physiologic functions between the peripheral nervous system (PNS) and the central nervous system (CNS). New information regarding metabolic change within the DRG has dispelled this supportive passive role and suggests that the DRG is an active, not a passive, organ, in the process of the development of chronic pain. ⋯ The DRG is as involved in the process of generating NP as is the nociceptor and the dorsal horn of the spinal cord.
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Pannexin 1 (panx1) is a large-pore membrane channel expressed in many tissues of mammals, including neurons and glial cells. Panx1 channels are highly permeable to calcium and adenosine triphosphatase (ATP); on the other hand, they can be opened by ATP and glutamate, two crucial molecules for acute and chronic pain signaling in the spinal cord dorsal horn, thus suggesting that panx1 could be a key component for the generation of central sensitization during persistent pain. In this study, we examined the effect of three panx1 blockers, namely, 10panx peptide, carbenoxolone, and probenecid, on C-reflex wind-up activity and mechanical nociceptive behavior in a spared nerve injury neuropathic rat model involving sural nerve transection. ⋯ Intrathecal administration of the panx1 blockers significantly depressed the spinal C-reflex wind-up activity in both neuropathic and sham control rats, and decreased mechanical hyperalgesia in neuropathic rats without affecting the nociceptive threshold in sham animals. Western blotting showed that panx1 was similarly expressed in the dorsal horn of lumbar spinal cord from neuropathic and sham rats. The present results constitute the first evidence that panx1 channels play a significant role in the mechanisms underlying central sensitization in neuropathic pain.