European journal of pain : EJP
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The present study was undertaken to characterize whether the pharmacologic interaction between duloxetine, a balanced serotonergic and noradrenergic reuptake inhibitor, and the non-steroidal anti-inflammatory drug ibuprofen was simply additive, less than additive, or greater than additive (i.e., synergistic) in preclinical models of visceral and inflammatory pain, specifically acetic acid-induced writhing in mice and carrageenan-induced thermal hyperalgesia and mechanical allodynia in rats. ⋯ Our data indicate that duloxetine and ibuprofen have synergistic efficacy in a visceral and an inflammatory pain model in rodents, and suggest that duloxetine and ibuprofen in combination may provide a useful approach to the clinical treatment of persistent pain, particularly inflammation-related pain.
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Comparative Study
Can a sexually dimorphic index of prenatal hormonal exposure be used to examine cold pressor pain perception in men and women?
There is considerable evidence to suggest that important differences exist between men and women in their experience of pain. Research has now turned to determine what the mechanisms of such differences actually are. One potential explanation is the effect of sex hormones, especially those typically found in greater concentration within women, e.g., estrogen, progesterone. ⋯ Although some significant relationships were found between digit ratio/digit length and cold pressor pain reports they were relatively inconsistent. Furthermore, the main finding, that pain thresholds were positively related to digit ratio in women but not men, is somewhat inconsistent with predictions. The results are discussed in light of methods for investigating the effect of prenatal hormonal exposure on pain sensitivity in men and women.
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We previously found that for both men and women odors influence mood, which in turn influences pain unpleasantness perception. Others showed that the steroid androstadienone modulates mood differently in men and women, improving mood in women and worsening it or leaving it unchanged in men. Based on its dissociable effect on mood, we hypothesized that women exposed to androstadienone would report lower pain unpleasantness than when exposed to the vehicle, while men would show no change or the reverse pattern. Because of the expected beneficial effect of pleasant odors on mood in both men and women, all subjects should report lower pain unpleasantness when exposed to the pleasant odor compared to the unscented air. ⋯ Planned comparisons confirmed that, in the absence of pain, androstadienone improved mood only in women, while the pleasant odorants improved mood for all subjects. However, these positive mood changes did not persist with the introduction of pain. Consistent with the absence of positive mood changes, pain unpleasantness was not modulated. Unexpectedly, the presence of androstadienone increased perceived pain intensity especially in women, suggesting an effect of androstadienone on pain perception, independent of mood changes. Heightened attentional state may be responsible.
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Mounting evidence supports the hypothesis that spinal microglia modulate the development and maintenance of some chronic pain states. Here we examined the role of spinal microglia following both peripheral inflammatory insult and peripheral nerve injury. We observed significant ipsilateral dorsal horn microglia activation 2 weeks after injury and bilateral activation 50 days following nerve injury as well as 24 h following intraplantar zymosan but not intraplantar complete Freund's adjuvant (CFA). ⋯ These data suggest a role for spinal glia in the persistence of mechanical hyperalgesia following peripheral nerve injury. However, activation of spinal microglia contralaterally did not correlate to nociception. Furthermore, it would appear that the time course of microglia activation and their contribution to inflammatory pain is dependent on the inflammatory stimulus administered.
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Multicenter Study
Adult attachment variables predict depression before and after treatment for chronic pain.
The complex relationship between chronic pain and depression has long been of clinical and empirical interest. Although attachment theory has been described as a "theory of affect regulation", and has been lauded as a developmental framework for chronic pain, surprisingly little research specifically considers the links between adult attachment variables and pain-related depression. ⋯ Of particular interest was the finding that comfort with closeness was the unique predictor of lower levels of post-treatment depression, usurping pain intensity and pre-treatment depression. These results are discussed in terms of clinical implications, and suggest that adult attachment theory may prove a valuable perspective in pain treatment programs.