European journal of pain : EJP
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Somatostatin (SST) in spinal cord has been linked with the inhibition of nociceptive neurotransmission in several experimental paradigms. The SST2 receptor (SSTR2) is the main SST receptor subtype in the superficial dorsal horn (DH) and is activated, besides to the naïve peptide, by the SST synthetic analogue octreotide (OCT). In the present work, we have studied the central effects of SSTR2 activation on capsaicin (CAP)-induced glutamate release in mouse DH. ⋯ A subset of them was also found to express the CAP receptor TRPV1. These data show that the SST analogue OCT inhibits CAP-mediated activation of non-peptidergic nociceptive PAFs in lamina II. Our data indicate that SSTR2a plays an important role in the pre-synaptic modulation of central excitatory nociceptive transmission in mouse.
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To study the effects of occupational class, physical and psychosocial working conditions, health behaviours, and pain in the low back and the neck on sciatic pain among middle-aged employees. ⋯ Manual occupational class in both genders and semi-professional occupations in men, unhealthy behaviours and previous pain both in the neck and the lower back predicted sciatica, while physical and psychosocial working conditions had no independent effect.
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Randomized Controlled Trial
Self-reported sleep duration associated with distraction analgesia, hyperemia, and secondary hyperalgesia in the heat-capsaicin nociceptive model.
Although sleep deprivation is known to heighten pain sensitivity, the mechanisms by which sleep modifies nociception are largely unknown. Few studies of sleep-pain interactions have utilized quantitative sensory testing models that implicate specific underlying physiologic mechanisms. One possibility, which is beginning to receive attention, is that differences in sleep may alter the analgesic effects of distraction. ⋯ Individuals who slept less than 6.5 h/night in the month prior to the study experienced significantly less behavioral analgesia, increased skin flare and augmented secondary hyperalgesia. These findings suggest that reduced sleep time is associated with diminished analgesic benefits from distraction and/or individuals obtaining less sleep have a reduced ability to disengage from pain-related sensations. The secondary hyperalgesia finding may implicate central involvement, whereas enhanced skin flare response suggests that sleep duration may also impact peripheral inflammatory mechanisms.
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Patients with Alzheimer's disease (AD) are administered fewer analgesics and report less clinical pain compared with their cognitively-intact peers, prompting much speculation about the likely impact of neurodegeneration on pain perception and processing. This study used functional connectivity analysis to examine the impact of AD on the integrated functioning of brain regions mediating the sensory, emotional, and cognitive aspects of pain. Fourteen patients with AD and 15 controls attended two experimental sessions. ⋯ Between-group comparisons revealed enhanced functional connectivity between the DLPFC and the anterior mid cingulate cortex, periaqueductal grey, thalamus, hypothalamus, and several motor areas in patients with AD compared with control group. Likewise, inter-regional functional connectivity across most regions of the predefined pain network was shown to be greater in the patient group, with the enhanced functional connectivity centred on three nodes: the DLPFC-R, hypothalamus, and PAG. The results of this study support previous research suggesting an interplay between pain and cognitive processes in patients with AD.
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Randomized Controlled Trial
The anticonvulsant levetiracetam for the treatment of pain in polyneuropathy: a randomized, placebo-controlled, cross-over trial.
Levetiracetam is an anticonvulsant which is assumed to act by modulating neurotransmitter release via binding to the vesicle protein SV2A. This could have an impact on signaling in the nociceptive system, and a pilot study indicated relief of neuropathic pain with levetiracetam. ⋯ This study indicates that the anticonvulsant levetiracetam has no clinically relevant effect on painful polyneuropathy.