Pain
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The role of anxiety in pain is less well understood than the role of depression. Based on recent conceptual thinking about worry and pain, we explored the relationship between pain status and worry about health and anxiety in 1217 community-dwelling men aged 70 years or older who participated in the baseline phase of the Concord Health and Ageing in Men Project study, a large population-based epidemiological study of healthy ageing based in Sydney, Australia. We hypothesised that worry about health would be associated with having persistent pain, and that the association would be stronger in the presence of co-existing pain-related interference with activities (intrusive pain). ⋯ These findings suggest that at a population level, subthreshold anxiety and pain are strongly related, and worry about health occurs much more commonly than anxiety itself. To our knowledge, this is the first study to explore, specifically, the relationship between pain status and worry about health in older men. In older community-dwelling men, pain was robustly associated with worry about health, highlighting the potential importance of subthreshold anxiety-related psychological factors.
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Comparative Study
Intraepidermal nerve fiber loss corresponds to the development of taxol-induced hyperalgesia and can be prevented by treatment with minocycline.
Loss of intraepidermal nerve fibers (IENFs) has been speculated to play a critical role in the development of various neuropathies. In this study, the density of IENFs were studied over time during the induction of Taxol (Bristol-Myers Squibb, NY, USA)-induced chemoneuropathy and compared with the changes in IENFs in animals co-treated with Taxol plus the protective agent minocycline. Rats were injected (intraperitoneally) with 2mg/kg of Taxol every other day for four injections (day 1, 3, 5, and 7). ⋯ Animals receiving minocycline plus Taxol showed no hyperalgesia or loss of IENFs. This study confirms, for the first time, that a loss of IENFs occurs as a neuropathy develops, and further shows a protection against both IENF loss and hyperalgesia with minocycline treatment. The progression of Taxol-induced mechanical hypersensitivity coincides with loss of intraepidermal nerve fibers, and the hyperalgesia and nerve fiber loss were prevented with minocycline treatment.
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Tumor necrosis factor-alpha (TNF-α) is a key proinflammatory cytokine. It is generally believed that TNF-α exerts its effects primarily via TNF receptor subtype-1 (TNFR1). We investigated the distinct roles of TNFR1 and TNFR2 in spinal cord synaptic transmission and inflammatory pain. ⋯ Our findings support a central role of TNF-α in regulating synaptic plasticity (central sensitization) and inflammatory pain via both TNFR1 and TNFR2. Our data also uncover a unique role of TNFR2 in mediating early-phase inflammatory pain. TNF-α is shown to play a critical role in regulating spinal cord synaptic plasticity and central sensitization, and TNFR1 and TNFR2 play a distinct role in regulating different phases of inflammatory pain.
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Episodic migraine (EM) may evolve into the more disabling chronic migraine (CM, monthly migraine days ≥ 8 and headache days ≥ 15) with unknown mechanism. Aiming to elucidate the pathophysiology of CM and its relationship with EM, this study characterized the visual cortical responses in CM and EM. Neuromagnetic visual-evoked responses to left-hemifield checkerboard reversals were obtained in patients with EM (interictal or ictal states), CM (interictal) and age-matched controls. ⋯ These CM features also characterized the P100m in the ictal state of EM (n=9). There was no difference of P100m between CM and ictal state of EM. In conclusion, patients with CM demonstrate a persistent ictal-like excitability pattern of the visual cortex between migraine attacks which may implicate central inhibitory dysfunction.