Articles: hyperalgesia.
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The aim of the present study was to test the hypothesis that the TRPV4-NO-cGMP-PKG cascade is involved in the maintenance of thermal hyperalgesia following chronic compression of the dorsal root ganglion (DRG) (the procedure hereafter termed CCD) in rats. CCD rats showed thermal hyperalgesia and increased nitrite production. ⋯ In addition, the phorbol ester 4alpha-phorbol 12,13-didecanoate (4alpha-PDD, TRPV4 synthetic activator, 1 nmol), co-administered with L-NAME (300 nmol), attenuated the suppressive effect of L-NAME on CCD-induced thermal hyperalgesia and nitrite production. Our data suggested that the TRPV4-NO-cGMP-PKG pathway could be involved in CCD-induced thermal hyperalgesia.
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Comparative Study
Bradykinin and nerve growth factor play pivotal roles in muscular mechanical hyperalgesia after exercise (delayed-onset muscle soreness).
Unaccustomed strenuous exercise that includes lengthening contraction (LC) often causes delayed-onset muscle soreness (DOMS), a kind of muscular mechanical hyperalgesia. The substances that induce this phenomenon are largely unknown. Peculiarly, DOMS is not perceived during and shortly after exercise, but rather is first perceived after approximately 1 d. ⋯ We also showed that rat NGF sensitized thin-fiber afferents to mechanical stimulation in the periphery after 10-20 min. Thus, NGF upregulation through activation of B(2) bradykinin receptors is essential (though not satisfactory) to mechanical hyperalgesia after exercise. The present observations explain why DOMS occurs with a delay, and why lengthening contraction but not shortening contraction induces DOMS.
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Cisplatin is primarily used for treatment of ovarian and testicular cancer. Oxaliplatin is the only effective treatment for metastatic colorectal cancer. Both are known to cause dose related, cumulative toxic effects on the peripheral nervous system and thirty to forty percent of cancer patients receiving these agents experience painful peripheral neuropathy. The mechanisms underlying painful platinum-induced neuropathy remain poorly understood. Previous studies have demonstrated important roles for TRPV1, TRPM8, and TRPA1 in inflammation and nerve injury induced pain. ⋯ These results indicate that TRPV1 and TRPA1 could contribute to the development of thermal hyperalgesia and mechanical allodynia following cisplatin-induced painful neuropathy but that TRPV1 has a crucial role in cisplatin-induced thermal hyperalgesia in vivo.
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Scand. J. Gastroenterol. · Mar 2010
Comparative StudyAcid hypersensitivity in patients with eosinophilic oesophagitis.
Painful symptoms are prevalent in patients with eosinophilic oesophagitis but experimental data are sparse. The aim of this study was to compare the pain response to experimental oesophageal stimulation in 14 patients with eosinophilic oesophagitis and 15 healthy volunteers. ⋯ Patients with eosinophilic oesophagitis are hypersensitive to acid perfused in the oesophagus, and pathophysiologic findings are likely confined to the peripheral tissue. Reflux from physiological acid may play a role in the symptoms of eosinophilic oesophagitis.
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Anesthesia and analgesia · Mar 2010
Randomized Controlled TrialNocebo-induced hyperalgesia during local anesthetic injection.
Common practice during local anesthetic injection is to warn the patient using words such as: "You will feel a big bee sting; this is the worst part." Our hypothesis was that using gentler words for administration of the local anesthetic improves pain perception and patient comfort. One hundred forty healthy women at term gestation requesting neuraxial analgesia were randomized to either a "placebo" ("We are going to give you a local anesthetic that will numb the area and you will be comfortable during the procedure") or "nocebo" ("You are going to feel a big bee sting; this is the worst part of the procedure") group. ⋯ Median verbal analog scale pain scores were lower when reassuring words were used compared with the harsher nocebo words (3 [2-4] vs 5 [3-6]; P < 0.001). Our data suggest that using gentler, more reassuring words improves the subjective experience during invasive procedures.