Articles: hyperalgesia.
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Toxicol. Appl. Pharmacol. · Apr 2019
Evidence for the involvement of opioid and cannabinoid systems in the peripheral antinociception mediated by resveratrol.
Despite all the development of modern medicine, around 100 compounds derived from natural products were undergoing clinical trials only at the end of 2013. Among these natural substances in clinical trials, we found the resveratrol (RES), a pharmacological multi-target drug. RES analgesic properties have been demonstrated, although the bases of these mechanisms have not been fully elucidated. ⋯ Peripheral antinociception of RES intermediate-dose (50 μg/paw) was increased by: (i) bestatin, inhibitor of endogenous opioid degradation involved-enzymes; (ii) MAFP, inhibitor of anandamide amidase; (iii) JZL184, inhibitor of 2-arachidonoylglycerol degradation involved-enzyme; (iv) VDM11, endocannabinoid reuptake inhibitor. Acute and peripheral administration of RES failed to affect the amount of μOR, CB1R and CB2R. Experimental data suggest that RES induces peripheral antinociception through μOR and CB1R activation by endogenous opioid and endocannabinoid releasing.
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Randomized Controlled Trial
Somatosensory profiles in acute herpes zoster and predictors of postherpetic neuralgia.
This prospective cohort study aimed to characterize the sensory profile during acute herpes zoster (AHZ) and to explore sensory signs as well as physical and psychosocial health as predictors for postherpetic neuralgia (PHN). Results of quantitative sensory testing of 74 patients with AHZ at the affected site and at the distant contralateral control site were compared to a healthy control group. Pain characteristics (Neuropathic Pain and Symptom Inventory and SES), physical functioning, and psychosocial health aspects (Pain Disability Index, SF-36, and STAI) were assessed by questionnaires. ⋯ Pain Disability Index (P = 0.036) and SES affective pain perception scores (P = 0.031) were over 50% higher, and 6 of 8 SF-36 subscores were over 50% lower (P < 0.045) in PHN. Sensory profiles in AHZ indicate deafferentation and central but not peripheral sensitization. Sensory signs at distant body sites, strong affective pain perception, as well as reduced quality of life and physical functioning in the acute phase may reflect risk factors for the transition to PHN.
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The counterirritation phenomenon known as conditioned pain modulation, or diffuse noxious inhibitory control in animals, is of increasing interest due to its utility in predicting chronic pain and treatment response. It features considerable interindividual variability, with large subsets of pain patients and even normal volunteers exhibiting hyperalgesia rather than hypoalgesia during or immediately after receiving a conditioning stimulus. ⋯ In a series of parametric studies, we show that this hyperalgesia can be reliably observed using multiple conditioning stimuli (acetic acid and orofacial formalin), test stimuli (hindpaw and forepaw-withdrawal, tail-withdrawal, hot-plate, and von Frey tests) and genotypes (CD-1, DBA/2, and C57BL/6 mice and Sprague-Dawley rats). Although the magnitude of the hyperalgesia is dependent on the intensity of the conditioning stimulus, we find that the direction of effect is dependent on the effective test stimulus intensity, with lower-intensity stimuli leading to hyperalgesia and higher-intensity stimuli leading to hypoalgesia.
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Randomized Controlled Trial
TRPA1 Sensitization Produces Hyperalgesia to Heat but not to Cold Stimuli in Human Volunteers.
Transient receptor potential ion channels play a role in thermal hyperalgesia and are among targets of novel analgesics. However, a role of TRPA1 in either heat or cold hyperalgesia is controversial. In this study, changes in thermal sensitivity were assessed following topical application of a specific sensitizer of TRPA1 and compared with the effects of sensitizers of TRPV1 and TRPM8. ⋯ The observation that the TRPA1 irritant cinnamaldehyde induced heat hyperalgesia at an effect sizes comparable with that of capsaicin attributes TRPA1 a role in human heat-induced pain. Results suggest the inclusion of heat pain as a major efficacy measure in human experimental studies of the effects of TRPA1 antagonists and the development of TRPA1 antagonists for clinical pain settings involving heat hyperalgesia.