European journal of pain : EJP
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Although polymorphisms of the catechol-O-methyl transferase (COMT) gene have been implicated in altered pain sensitivity, results concerning the association between COMT gene polymorphisms and fibromyalgia (FM) are equivocal. We assessed the associations between COMT single-nucleotide polymorphisms (SNP) and FM risk and symptom severity. ⋯ By contrast to Caucasian and Latin-American populations, the COMT gene polymorphisms are associated with FM risk and pain sensitivity in Korean FM patients, suggesting ethnic variation in COMT gene polymorphisms.
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Widespread musculoskeletal pain (WSP) and obesity frequently co-occur and may have shared risk factors. We aimed to investigate whether four dichotomized risk factors individually or jointly increase the risk for the onset of WSP and onset of obesity. ⋯ The onset of WSP and the onset of obesity were results of joint effects of exposures. Poor physical fitness was a key covariate in increasing the risk for both conditions. WHAT DOES THIS STUDY ADD?: In a general population, the new onset of widespread pain and new onset of obesity were results of joint effects of risk factors and particularly poor physical fitness. The study may aid in the identification of patients at risk of future disability.
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Numerous studies have found appraisals of pain as a source of potential threat or tissue damage influence pain perception and coping. Conversely, causal effects of challenge appraisals reflecting potential future benefits of bearing pain have received little attention. This experiment was designed to elucidate effects of appraising laboratory pain as a source of potential threat and challenge on pain perception and coping. ⋯ Findings underscore causal effects of pain appraisals on coping responses and pain perception. WHAT DOES THIS STUDY ADD?: Effects of challenge appraisals of pain as a source of potential future growth or development have not been considered in experimental pain research. Causal effects of primary appraisals of laboratory pain as a source of potential threat and challenge were elucidated in relation to pain perception and coping.
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Orexinergic neurons in the lateral hypothalamus (LH) play an important role in pain modulation. In addition, ventral tegmental area (VTA) is known as a part of descending pain modulatory circuitry. Little is known about the interaction between the LH and neural substrates involving in modulation of formalin-induced nociception. Accordingly, we aimed to examine the pain modulatory role of VTA orexin receptors in the formalin test. ⋯ Formalin test, a model of persistent inflammatory pain, mimics the conditions encountered in clinical situations. Pain modulatory role of orexinergic system in the formalin test through a neural pathway from the LH to the VTA provides the evidence that orexins can be useful therapeutic targets for chronic pain treatment. WHAT DOES THIS STUDY ADD?: There is a pathway from the lateral hypothalamus (LH) to the ventral tegmental area (VTA) which modulates biphasic formalin-induced pain. Blockade of VTA orexin receptors dose-dependently reduces LH-induced analgesia during both phases. Anti-analgesic effect of orexin receptor antagonists is more considerable during the late phase. Contribution of orexin-1 receptors to mediation of LH-induced analgesia is more than orexin-2 receptors during the late phase.
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Pain is associated with affective, cognitive and sensory dysfunction. Animal models can be used to observe ethologically relevant behaviours such as thigmotaxis, giving insight into how ongoing sensory abnormalities influence natural rodent behaviours. The amygdala is a complex group of nuclei implicated in the integration and generation of emotional behavioural responses, including those associated with pain, and a region known as the central amygdala is particularly associated with generation of behavioural responses, due to its links to the descending pain modulation pathways; as such, study of amygdalar c-Fos immunoreactivity can help identify the neuronal circuits involved. ⋯ This study provides evidence to support the role of the amygdala in thigmotactic open field behaviour following SNT. WHAT DOES THIS STUDY ADD?: Thigmotaxis and amygdala activation are positively correlated in rats following spinal nerve transection. Behavioural changes seen in sham animals did not correlate with amygdala activation, suggesting amygdala activation is related to nociceptive input. Evoked measures, such as hindpaw withdrawal, are not correlated with either thigmotaxis or amygdala activation, emphasizing the importance of complex behaviours when studying pain.