Articles: hyperalgesia.
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Hyperalgesic priming, a model of pain chronification in the rat, is mediated by ryanodine receptor-dependent calcium release. Although ryanodine induces priming in both sexes, females are 5 orders of magnitude more sensitive, by an estrogen receptor α (EsRα)-dependent mechanism. An inositol 1,4,5-triphosphate (IP3) receptor inhibitor prevented the induction of priming by ryanodine. ⋯ SIGNIFICANCE STATEMENT The present study demonstrates a mechanism that plays a role in the marked sexual dimorphism observed in a model of the transition to chronic pain, hyperalgesic priming. This mechanism involves a reciprocal interaction between the endoplasmic reticulum receptors, IP3 and ryanodine, in the induction of priming, regulated by estrogen receptor α in the nociceptor of female rats. The presence of this signaling pathway modulating the susceptibility of nociceptors to develop plasticity may contribute to our understanding of sex differences observed clinically in chronic pain syndromes.
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Remifentanil induced hyperalgesia (RIH) is characterized by stimulation evoked pain including allodynia and thermal hyperalgesia after remifentanil infusion. N-methyl-D-aspartate (NMDA) receptor was reported to be involved in the progress of RIH. We hypothesized that intrathecal MgSO4 could relieve hyperalgesia after remifentanil infusion via regulating phosphorylation of NMDA receptor NR2B subunit activity in this study. ⋯ Remifentanil induced hyperalgesia/allodynia could be ameliorated by Mg-mediated blockade targeting the NR2B subunit in NMDA receptors.
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Comparative Study
Differences in Topographical Pressure Pain Sensitivity Maps of the Scalp Between Patients With Migraine and Healthy Controls.
To investigate differences in topographical pressure pain sensitivity maps of the scalp between patients with migraine and healthy controls considering the chronicity (episodic/chronic) and side (strictly unilateral/bilateral) of the symptoms. ⋯ We found that patients with migraine exhibited generalized pressure pain hypersensitivity in the head as compared to healthy controls and that hypersensitivity was similar between episodic/chronic and unilateral/bilateral migraine. Topographical pressure pain sensitivity maps revealed an anterior to posterior gradient of pressure pain sensitivity in both migraine and control groups.
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Expectations can dramatically influence the perception of pain, as has been shown in placebo analgesia or nocebo hyperalgesia. Here, we investigated the role of expectation on the interruptive function of pain - the negative consequences of pain on cognitive task performance - in 42 healthy human subjects. ⋯ We show that the interruptive function of pain on concurrent visual task performance is influenced by expectation. Positive expectation can abolish the detrimental effects of pain on cognition. These expectancy effects on the interruptive function of pain are mediated by changes in functional connectivity between rostral ACC, posterior fusiform cortex and the hippocampus.
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To investigate differences in widespread pressure pain hyperalgesia in the trigemino-cervical and extra-trigeminal (distant pain-free) regions in women with frequent episodic (FETTH) and chronic (CTTH) tension-type headache. ⋯ Current results suggest the presence of similar local and widespread pressure hyperalgesia, not associated with anxiety or depression, in women with FETTH and CTTH supporting that localized and central manifestations are involved in both the episodic and chronic forms of tension-type headache.