Pain
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Anatomical studies demonstrate the presence of glutamate receptors on unmyelinated axons in peripheral cutaneous nerves. Pharmacological studies show that intraplantar injection of glutamate or glutamate agonists in the glabrous skin results in nociceptive behaviors. The present study describes a novel in vitro skin-nerve preparation using the glabrous skin from the rat hindpaw. ⋯ Exposure of A delta or C fibers to glutamate did not result in a decrease in von Frey thresholds. These data provide a physiological basis for the nociceptive behaviors that arise following intraplantar injection of glutamate or glutamate agonists. Furthermore, demonstration of glutamate-induced excitation and heat sensitization of nociceptors indicates that local or topical administration of glutamate receptor antagonists may have therapeutic potential for the treatment of pain.
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Nerve growth factor (NGF) regulates the nociceptive properties including sensitivity to capsaicin of a subset of dorsal root ganglion neurons, which express the high-affinity NGF receptor, trkA. Capsaicin sensitivity co-localizes with the expression of a cloned capsaicin receptor, vanilloid receptor type 1 (VR-1), which displays properties similar to the native capsaicin response. ⋯ NGF treatment increased both VR-1 mRNA expression and capsaicin evoked release of CGRP. These effects were inhibited by treatment with the trkA inhibitor k252a.
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Randomized Controlled Trial Clinical Trial
Expectations of analgesia do not affect spinal nociceptive R-III reflex activity: an experimental study into the mechanism of placebo-induced analgesia.
The purpose of this study was to investigate whether placebo analgesia is mediated by the release of beta-endorphin. In addition to subjective pain reports, we included an objective physiological parameter of nociception reflected by the opioid sensitive nociceptive R-III reflex. Placebo consisted of strong suggestions of pain relief and an intravenous injection of saline. ⋯ Consistently, the antagonizing effects of naloxone were negligible. A subgroup analysis of those who did show a placebo response as indicated on the VAS did not support the supposition that beta-endorphin is released due to placebo suggestion. It is suggested that intensified stimuli and a more effective procedure to induce placebo analgesia (e.g. conditioning) may produce a proper placebo effect.
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Both physicians and nurses are responsible for adequate pain management. The aim of this study was to assess pain management behavior of physicians and nurses, and to evaluate the effects of a Pain Monitoring Program for nurses on the extent to which nurses administer analgesics. The Pain Monitoring Program consisted of two components: educating nurses about pain, pain assessment and pain management; and implementing daily pain assessment by means of a numeric rating scale. ⋯ Based on this study it can be concluded that the use of a simple method such as a numeric rating scale together with pain education for nurses is effective in improving the administration of analgesics by nurses. These are important results because nurses play an essential role in helping patients to cope with their pain. Because the Pain Monitoring Program (PMP) was effective in a heterogeneous population in multiple care settings, the possibility of implementing the PMP in routine nursing practice should be considered.