Pain
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Randomized Controlled Trial Comparative Study
No pain no gain? Pursuing a competing goal inhibits avoidance behavior.
This experiment investigated pain-related avoidance behavior in context of competing goals. Participants (N=56) were presented trials of 2 different tasks of which 1 task could produce pain. They were free to decide whether or not to perform trials of these tasks. ⋯ Furthermore, the association between pain-related avoidance behavior and fear of pain was smaller in the competition group than in the control group. The findings indicate that the emergence of pain-related avoidance behavior depends upon the motivational context, and that the association between pain-related fear and avoidance is not stable. This study has implications for our understanding of disability, and points to the need to consider avoidance behavior within a broad context of multiple, often competing, goals.
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Triptans, a family of 5-hydroxytryptamine (5-HT) 1B, 1D, and 1F receptor agonists, are used in the acute treatment of migraine attacks. The site of action and subtypes of the 5-HT(1) receptor that mediate the antimigraine effect have still to be identified. This study investigated the mRNA expression of these receptors and the role of 5-HT(1) receptor subtypes in controlling the release of calcitonin gene-related peptide (CGRP) in rat dura mater, trigeminal ganglion (TG), and trigeminal nucleus caudalis (TNC). ⋯ The 5-HT(1F) agonist (LY-344864) was effective in the dura mater (26% iCGRP inhibition), and the 5-HT(1D) agonist (PNU-142633) had a significant effect in the TNC (48%), whereas the 5-HT(1B) agonist (CP-94253) was unable to reduce the iCGRP release in all tissues studied. We found that sumatriptan reduced the iCGRP release via activation of 5-HT(1D) and 5-HT(1F) receptor subtypes. The 5-HT(1F) receptor agonist was effective only in peripheral terminals in dura mater, whereas the 5-HT(1D) agonist had a preferential effect on central terminals in the TNC.
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Comparative Study
Inflammation-induced decrease in voluntary wheel running in mice: a nonreflexive test for evaluating inflammatory pain and analgesia.
Inflammatory pain impacts adversely on the quality of life of patients, often resulting in motor disabilities. Therefore, we studied the effect of peripheral inflammation induced by intraplantar administration of complete Freund's adjuvant (CFA) in mice on a particular form of voluntary locomotion, wheel running, as an index of mobility impairment produced by pain. The distance traveled over 1 hour of free access to activity wheels decreased significantly in response to hind paw inflammation, peaking 24 hours after CFA administration. ⋯ The CFA-induced decrease in voluntary wheel running was dose-dependently reversed by subcutaneous administration of antiinflammatory and analgesic drugs, including naproxen (10-80 mg/kg), ibuprofen (2.5-20mg/kg), diclofenac (1.25-10mg/kg), celecoxib (2.5-20mg/kg), prednisolone (0.62-5mg/kg), and morphine (0.06-0.5mg/kg), all at much lower doses than reported in most rodent models. Furthermore, the doses that induced recovery in voluntary wheel running did not reduce CFA-induced mechanical allodynia, indicating a greater sensitivity of the former as a surrogate measure of inflammatory pain. We conclude that monitoring changes in voluntary wheel running in mice during peripheral inflammation is a simple, observer-independent objective measure of functional changes produced by inflammation, likely more aligned to the global level of pain than reflexive measures, and much more sensitive to analgesic drug effects.
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Randomized Controlled Trial Comparative Study
Patients who display protective pain behaviors are viewed as less likable, less dependable, and less likely to return to work.
In the present study, participants (ie, observers) watched video sequences of patients with chronic back pain performing a physically demanding lifting task. Participants were asked to make judgments about patients' levels of pain and readiness to work. For each patient, observers were also asked to make judgments about personality traits relevant to work performance and employment. ⋯ Analyses also revealed that patients displaying protective pain behaviors were perceived as being significantly less likable, less dependable, and less ready to work than patients displaying other forms of pain behavior. Discussion addresses the processes by which pain behaviors might influence observers' judgments about patients' personality traits and readiness to work. Implications of the present findings for clinical practice and the management of patients presenting with pain conditions are also discussed.