European journal of pain : EJP
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The biobehavioural pain reactivity and recovery of preterm infants in the neonatal period may reflect the capacity of the central nervous system to regulate neurobiological development. ⋯ The infants exhibiting a high neonatal clinical risk showed high arousal during the puncture procedure and higher physiological reactivity in the recovery phase.
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Endogenous cannabinoids and peripheral cannabinoid CB2 receptors (CB2Rs) are involved in the antinociceptive effect of electroacupuncture (EA) on inflammatory pain. However, it is not clear how CB2R activation contributes to the antinociceptive effect of EA. The major proinflammatory cytokines, such as tumour necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and IL-6, are involved in inflammatory pain. ⋯ Furthermore, EA or AM1241 treatment significantly decreased the mRNA and protein levels of IL-1β, IL-6 and TNF-α in inflamed skin tissues. In addition, pretreatment with AM630 significantly reversed the inhibitory effect of EA on these cytokine levels in inflamed skin tissues. Our results suggest that EA reduces inflammatory pain and proinflammatory cytokines in inflamed skin tissues through activation of CB2Rs.
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Anxiety sensitivity has been included in the fear-avoidance model as a vulnerability factor to explain individual differences in fear of pain. Several studies have suggested that the relationship between anxiety sensitivity and some psychopathological disorders is mediated by experiential avoidance, an affect-related regulatory process that involves unwillingness to endure private experiences. The role of these constructs as vulnerability variables has not been investigated in chronic pain patients. ⋯ The alternative model, in which experiential avoidance mediates the relationship between anxiety sensitivity and pain fear-avoidance, gave a much worse fit. These results highlight the importance of both anxiety sensitivity and experiential avoidance as variables which could explain individual differences in pain fear-avoidance. Thus, in terms of prevention, it should be a priority to identify patients with increased anxiety sensitivity and experiential avoidance during the first stages of the development of chronic pain conditions.
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The most commonly used drugs against pain act by inhibiting the cyclooxygenases (COXs). Metamizol (dipyrone) inhibits the COXs and is widely used in Europe and Latin America as a non-opioid analgesic. One target of metamizol and other non-opioid analgesics is the periaqueductal grey matter (PAG), where they trigger descending inhibition of spinal nociceptive transmission. ⋯ In both cases, the antinociceptive effect of metamizol was reduced by a microinjection of AM251, an antagonist at the CB1 cannabinoid receptor, either into the LVL-PAG or into the rostral ventromedial medulla (RVM). The RVM is a downstream structure that funnels PAG-derived descending inhibition into the spinal cord. These results show that endocannabinoids and their CB1 receptor (1) contribute at the LVL-PAG to the antinociceptive effects of metamizol, and possibly other non-opioid analgesics; and (2) participate in the PAG-derived activation of RVM descending antinociceptive influences.