Pain
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VGF (nonacronymic) is a granin-like protein that is packaged and proteolytically processed within the regulated secretory pathway. VGF and peptides derived from its processing have been implicated in neuroplasticity associated with learning, memory, depression, and chronic pain. In sensory neurons, VGF is rapidly increased following peripheral nerve injury and inflammation. ⋯ In mice injected intradermally with complete Freund adjuvant, intrathecal treatment with anti-TLQP-21 immediately prior to or 5hours after induction of inflammation dose-dependently inhibited tactile hypersensitivity and thermal hyperalgesia. Intrathecal anti-TL21 administration also attenuated the development and maintenance of tactile hypersensitivity in the spared nerve injury model of neuropathic pain. These results provide evidence that endogenous TLQP-21 peptide contributes to the mechanisms of spinal neuroplasticity after inflammation and nerve injury.
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Eliminating publication bias requires ensuring public awareness of studies and access to results. Clinical trial registries provide basic trial information, but access to unbiased trial results is inadequate. Nearly all studies of trial registration and results reporting have been limited to the ClinicalTrials.gov registry. ⋯ Overall, only 46% of all trials had results available. Trials registered on ClinicalTrials.gov were significantly more likely to have results (52% vs. 18%, P<0.001), partly due to the ability to post results directly to the registry. In addition to the simple remedy of including trial registration numbers on all meeting abstracts and peer-reviewed papers, specific strategies are offered to facilitate identifying multiply registered studies and ensuring accurate pairing of results and publications.
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Central sensitization after peripheral nerve injury may result in ectopic neuronal activity in the spinal cord dorsal horn, implying a potential autonomous pain-generating mechanism. This study used peripheral nerve blockade and systemic lidocaine administration, with detailed somatosensory assessment, to determine the contribution of primary afferent input in maintaining peripheral neuropathic pain. Fourteen patients with neuropathic pain (7 with unilateral foot pain due to peripheral nerve injury and 7 with bilateral pain in the feet due to distal polyneuropathy) underwent comprehensive characterization of somatosensory function by quantitative sensory testing. ⋯ Intravenous lidocaine infusion reduced the spontaneous pain by 45.5% (±31.7%), and it reduced mechanical and thermal hypersensitivity in most patients who displayed such signs. However, the improvement in evoked hypersensitivity was not related to the effect of the drug on spontaneous pain intensity. This study demonstrated that regardless of the individual somatosensory phenotype and signs of central sensitization, primary afferent input is critical for maintaining neuropathic pain in peripheral nerve injury and distal polyneuropathy.
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Vulvodynia is a prevalent vulvovaginal pain condition that interferes with women's psychological health. Given the central role of sexuality and relationships in vulvodynia, relationship satisfaction may be an important moderator of daily partner responses to this pain and associated negative sequelae, such as depression. ⋯ Relationship satisfaction on the preceding day moderated the associations between partner responses and women's depressive symptoms in several significant ways: (1) On days after women reported higher relationship satisfaction than usual, their perception of greater facilitative male partner responses was associated with their decreased depression; (2) on days after women reported lower relationship satisfaction than usual, their perception of greater negative male partner responses was associated with their increased depression; (3) on days after men reported higher relationship satisfaction than usual, their self-reported higher negative responses were associated with decreased women's depression, and higher solicitous responses were associated with increased women's depression, whereas (4) on days after men reported lower relationship satisfaction than usual, their self-reported higher negative responses were related to increased women's depression, and higher solicitous responses were associated with decreased women's depression. Targeting partner responses and relationship satisfaction may enhance the quality of interventions aimed at reducing depression in women with vulvodynia.
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Animal studies have suggested that the cerebellum, in addition to its motor functions, also has a role in pain processing and modulation, possibly because of its extensive connections with the prefrontal cortex and with brainstem regions involved in descending pain control. Consistently, human imaging studies have shown cerebellar activation in response to painful stimulation. However, it is presently not clear whether cerebellar lesions affect pain perception in humans. ⋯ In contrast, heat and pressure pain thresholds were not significantly different between groups. These results show that, after cerebellar infarction, patients perceive heat and repeated mechanical stimuli as more painful than do healthy control subjects and have deficient activation of endogenous pain inhibitory mechanisms (offset and placebo analgesia). This suggests that the cerebellum has a previously underestimated role in human pain perception and modulation.