European journal of pain : EJP
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Spinal cord injury (SCI) results in the development of chronic pain that is refractory to conventional treatment. Progesterone, a neuroprotective steroid, may offer a promising perspective in pain modulation after central injury. Here, we explore the impact of progesterone administration on the post-injury inflammatory cascade involving the enzymes cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) at the spinal cord level. We also analyse pain behaviours, the profile of glial cell activation, and IκB-α mRNA levels, as an index of NF-κB transactivation. ⋯ Our results suggest that progesterone, by modulating early neuroinflammatory events triggered after SCI, may represent a useful strategy to prevent the development of central chronic pain.
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The aim of the study was to test the hypothesis that associations with specific stress systems [hypothalamic-pituitary-adrenal (HPA) and growth hormone (GH) axes] would increase as the number of unexplained disorders increased while accounting for the possible confounding effects of psychosocial factors. ⋯ Although previous studies have shown that stress axis function acts to moderate the risk of onset of some of these disorders, the present study shows that the degree of dysfunction is not correlated with a corresponding increasing load of disorders. The uncertainty surrounding the role of these biomarkers in the aetiology of unexplained disorders needs further investigation.
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Review
Heart rate variability and experimentally induced pain in healthy adults: A systematic review.
Reactivity of the autonomic nervous system to experimental pain stimuli has been extensively studied using measures of heart rate and blood pressure. Heart rate variability (HRV) attempts to tease out the relative contributions of sympathetic and parasympathetic activity in the autonomic control of the heart and may therefore be more appropriate to investigate autonomic response to short-term nociceptive stimulation in detail. The current evidence on HRV and experimentally induced pain has not yet been synthesized within a systematic review. ⋯ HRV has several advantages compared to other measures of autonomic reactivity in studies investigating physiological response to nociceptive stimulation. Future studies should focus on comparisons between different methods of pain induction, interindividual variability in pain sensitivity by baseline autonomic activity, and the implications of both on the use of HRV within routine clinical evaluations.
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Chemokine (C-C motif) ligand 2 (CCL2) participates in different mechanisms contributing to the spinal cord inflammation and pain development after sciatic nerve injury. Recent data also support its role in orofacial thermal hypersensitivity, although its implication in different phases of trigeminal pain emergence is unclear. We assessed the importance of CCL2 signalling in biochemical and behavioural alterations during the early and late stages following chronic constriction injury of infraorbital nerve (ION-CCI), a model of peripheral traumatic trigeminal pain. ⋯ Our data suggest that CCL2 is involved principally in the early events accompanying the ION lesion rather than in long-term alterations and the maintenance of trigeminal mechanical hypersensitivity.