Articles: neuropathic-pain.
-
Pharmacol. Biochem. Behav. · Dec 2014
Antihyperalgesic effect of 5-HT7 receptor activation on the midbrain periaqueductal gray in a rat model of neuropathic pain.
The 5-HT7 receptor is the most recently discovered receptor for 5-hydroxytryptamine (5-HT), and only little is known about the analgesic potential of this receptor. Adenosine triphosphate (ATP) modulates pain transmission by activating P2X/P2Y receptors, in which the P2X3 subtype is an important target for this effect. This study examined the antihyperalgesic effect of the 5-HT7 receptors in the ventrolateral midbrain periaqueductal gray (vlPAG), a crucial site for endogenous pain inhibition. ⋯ Furthermore, the antihyperalgesic effect of the 5-HT7 receptor was partially but significantly blocked by A-317491 pretreatment. These data indicate that the 5-HT7 receptor in the vlPAG exerts an antihyperalgesic effect on rats with neuropathic pain. The 5-HT7 and P2X3 receptors interact in the vlPAG and exhibit an analgesic action through the enhanced function of the endogenous analgesic system.
-
Although diabetes mellitus (DM) is often associated with painful neuropathic syndromes, a significant number of DM patients suffer from non-neuropathic (nociceptive) pain. Unfortunately, there is insufficient data on the epidemiology of nociceptive pain in DM patients and its effect on their quality of life. ⋯ The impact of neuropathic pain in DM patients is much more significant than nociceptive pain and affects their quality of life and daily function to a greater degree.
-
Chemotherapy-induced peripheral neuropathy accompanied by chronic neuropathic pain is the major dose-limiting toxicity of several anticancer agents including the taxane paclitaxel (Taxol). A critical mechanism underlying paclitaxel-induced neuropathic pain is the increased production of peroxynitrite in spinal cord generated in response to activation of the superoxide-generating enzyme, NADPH oxidase. Peroxynitrite in turn contributes to the development of neuropathic pain by modulating several redox-dependent events in spinal cord. ⋯ The first relies on inhibition of the redox-sensitive transcription factor (NFκB) and mitogen activated protein kinases (ERK and p38) resulting in decreased production of neuroexcitatory/proinflammatory cytokines (TNF-α, IL-1β) and increased formation of the neuroprotective/anti-inflammatory IL-10. The second involves inhibition of redox-mediated posttranslational tyrosine nitration and modification (inactivation) of glia-restricted proteins known to play key roles in regulating synaptic glutamate homeostasis: the glutamate transporter GLT-1 and glutamine synthetase. Our results unravel a mechanistic link into biomolecular signaling pathways employed by A3AR activation in neuropathic pain while providing the foundation to consider use of A3AR agonists as therapeutic agents in patients with chemotherapy-induced peripheral neuropathy.
-
Research on placebo analgesia and nocebo hyperalgesia has primarily included healthy subjects or acute pain patients, and it is unknown whether these effects can be obtained in ongoing pain in patients with chronic pain caused by an identifiable nerve injury. Eighteen patients with postthoracotomy neuropathic pain were exposed to placebo and nocebo manipulations, in which they received open and hidden administrations of pain-relieving (lidocaine) or pain-inducing (capsaicin) treatment controlled for the natural history of pain. Immediately after the open administration, patients rated their expected pain levels on a mechanical visual analogue scale (M-VAS). ⋯ Pain increases during nocebo were nonsignificant (P=.394 to 1.000). To our knowledge, this is the first study to demonstrate placebo effects in ongoing neuropathic pain. It provides further evidence for placebo-induced reduction in hyperalgesia and suggests that patients' expectations coexist with emotional feelings about treatments.
-
Clin Neurol Neurosurg · Dec 2014
Peripheral field stimulation for thoracic post herpetic neuropathic pain.
Post herpetic neuralgia is a chronic, debilitating pain with very few management options and is often refractory to treatment. We present our experience with a series of 4 patients who underwent subcutaneous peripheral field stimulation for treatment of thoracic post herpetic neuropathic pain. ⋯ Peripheral field stimulation for the treatment of post herpetic neuropathic pain is a safe and effective method for pain relief for an extremely complex problem with very few solutions. Patient selection and proper lead placement is most important for the success of treatment.