The journal of pain : official journal of the American Pain Society
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Placebo treatments and healing rituals share much in common, such as the effects of expectancy, and have been used since the beginning of human history to treat pain. Previous mechanistic neuroimaging studies investigating the effects of expectancy on placebo analgesia have used young, healthy volunteers. Using functional magnetic resonance imaging (fMRI), we aimed to investigate the neural mechanisms by which expectancy evokes analgesia in older adults living with a chronic pain disorder and determine whether there are interactions with active treatment. ⋯ However, there were different patterns of changes in fMRI indices of brain activity associated with verum and sham treatment modalities specifically in the lateral prefrontal cortex. We also found that continuous electroacupuncture in knee OA patients can evoke significant regional coherence decreases in pain associated brain regions. Our results suggest that expectancy modulates the experience of pain in knee OA patients but may work through different pathways depending on the treatment modality and, we speculate, on pathophysiological states of the participants.
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Provoked vestibulodynia (PVD) is a chronic pelvic pain disorder affecting 16% of the female population. Neuroimaging studies have highlighted central abnormalities in PVD, similar to other chronic pelvic pain disorders, including brain regions involved in sensory processing and modulation of pain. The aim of the study was to determine alterations in the subvoxel, microstructural organization within tissues in PVD compared with healthy control participants (HCs) and a disease control group (irritable bowel syndrome [IBS]). ⋯ PVD subjects showed greater MD in the basal ganglia compared with HCs (higher MD in the internal capsule and pallidum) and IBS (higher MD in the putamen and pallidum). Increases in MD were associated with increased vaginal muscle tenderness and vulvar pain. The current findings highlight possible shared mechanisms between 2 different pelvic pain disorders, but also highlight the widespread alterations observed specifically in PVD compared with HCs.
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The analgesic effect of social support is proposed as a function of social support modulating perceived threat of painful stimuli. In the current study, we directly examined the social buffering effect in the context of the threat of pain. Eighteen healthy participants were subjected to the threat of pain while they held the hand of a close other, a stranger, or not at all. ⋯ Interestingly, decreased heart rate and frontal theta in the close other hand-holding condition were uniquely associated with greater pain reduction during subsequent nociceptive stimulation. Neural changes were source-localized to the insular cortex and the rostral-ventral portions of anterior cingulate cortex, regions involved in the processing of threat and pain. Together, our data build upon work to date linking social support to pain by showing autonomic and neurophysiological changes associated with pain reduction.
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Low back pain (LBP) patients show reorganized trunk muscle activity but if similar changes are manifest in recurrent LBP (R-LBP) patients during asymptomatic periods remains unknown. In 26 healthy and 27 currently asymptomatic R-LBP participants electromyographic activity (EMG) was recorded from trunk and gluteal muscles during series of stepping up and down on a step bench before and during experimentally intramuscular induced unilateral and bilateral LBP. Pain intensity was assessed using numeric rating scale (NRS) scores. ⋯ In both groups, bilateral compared with unilateral experimental NRS scores were higher (P < .001) and patients compared with controls reported higher NRS scores during both pain conditions (P < .04). In patients, unilateral pain decreased ΔRMS-EMG in the Iliocostalis muscle and bilateral pain decreased ΔRMS-EMG in all back and gluteal muscles during step tasks (P < .05) compared with controls. In controls, bilateral versus unilateral experimental pain induced increased step task duration and trunk RMS-EMG whereas both pain conditions decreased step task duration and trunk RMS-EMG in R-LBP patients compared with controls (P < .05).
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To investigate the effect of parental drug abuse on children, nociception, electrophysiological alteration, mRNA expression of opioid receptors, and expression of certain intracellular proteins in offspring of morphine-abstinent rats were studied. Adult male and female animals received water-soluble morphine for 21 days. Ten days after the last morphine administration, animals were placed for mating in 4 groups as follows: healthy (drug naive) female and male, morphine-abstinent female and healthy male, morphine-abstinent male and healthy female, morphine-abstinent male and morphine-abstinent female. ⋯ In addition, the expression of κ receptors was remarkably increased in the PFC in morphine-abstinent parent group, relative to the control group. The phosphorylated levels of extracellular regulated kinase 1/2 and cyclic adenosine monophosphate responsive element binding protein were significantly higher in the offspring of the morphine-abstinent parent(s) than the control group in the NAC. Our results indicated that endogenous opioid is altered in offspring of the morphine-exposed parent(s) and that heritage has a major role.