European journal of pain : EJP
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Fear avoidance (FA) has been identified as a risk factor for poor prognosis and a target for intervention in patients with low back pain (LBP), but the mechanisms involved need clarification. Experimental studies would benefit from the use of carefully developed and controlled stimuli representing avoided movements in back pain, and matched stimuli of movements to provide a credible control stimuli. Existing stimuli depicting avoided movements in LBP are static, do not include a set of control stimuli and do not control for possible systematic observer biases. ⋯ The use of video stimuli could advance research into the processes associated with FA through experimental paradigms. However, although small, the model gender effects should be carefully considered.
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Patients with schizophrenia show decreased sensitivity towards clinical and experimental painful conditions. To date, the exact underlying mechanisms are not completely understood. One method to examine central integrative processes of pain perception is the thermal grill illusion (TGI), in which interlacing cold and warm bars create the illusion of a painful sensation. ⋯ CPT and HPT, as well as temperature differentials for the perception of the TGI were increased in patients with schizophrenia as compared to controls. Similar to visual illusions, in which reduced contrast sensitivity has been shown to alter the perception of illusions, the discriminatory somatosensory deficit, which is reflected in higher CPT and HPT as well as the previously reported increased warmth perception thresholds, might account for the attenuation of TGI in patients.
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Some studies have shown a somatic nociceptive response due to the activation of transient receptor potential A1 channels (TRPA1), which is modulated by the TRPA1 antagonist HC-030031. However, a few studies report the role of TRPA1 in visceral pain. Therefore, we investigated the participation of TRPA1 in visceral nociception and the involvement of nitric oxide, the opioid system and resident cells in the modulation of these channels. ⋯ Our findings suggest that the blockade of TRPA1 attenuates visceral nociception by a mechanism independent of the modulation of resident cells, nitric oxide and opioid pathways.
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Previous studies have shown 17β-estradiol will reduce temporomandibular joint (TMJ) inflammation and hypersensitivity in female rats. Although male rats contain significant amounts of oestradiol, it was unknown whether a physiological concentration of 17β-estradiol would attenuate male TMJ inflammation and nociception. ⋯ Similar to females, male rats with TMJ inflammation showed a reduced nociceptive response after treatment with a physiological concentration of oestradiol suggesting the effects of oestradiol treatment were not constrained by organizational processes in the males.