Pain
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The transient receptor potential vanilloid channel 1 (TRPV1) is a nociceptive transducer located on nociceptive neurons. TRPV1 channels located on peripheral neurons mainly transduce the sense of heat and are also activated by low pH or capsaicin. The role of centrally located TRPV1 channels is not fully understood. ⋯ The results show that olvanil dose-dependently inhibited spontaneous and stimulus-induced activity within the trigeminocervical complex, whereas it had no effect on CSD susceptibility. We further demonstrated that the inhibiting effect of olvanil is mediated by vanilloid and cannabinoid receptor systems, thereby using the synergistic effects this dual mechanism offers. Curiously, TRPV1 receptor agonism may have anti-nociceptive properties through central mechanisms that would be of considerable interest to elucidate.
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Comparative Study
Differential effects of left/right neuropathy on rats' anxiety and cognitive behavior.
Chronic pain is frequently accompanied by a deterioration of emotional behavior and cognitive function. A small number of studies in humans concluded that pain-associated negative affect is more pronounced when pain is localized in the left side of the body. It has been suggested that such side bias results from cortical function lateralization. ⋯ On the contrary, SNI-R animals presented cognitive deficits in all tasks except in the reference memory, but displayed a normal anxiety-like profile. Our results show that left- and right-sided neuropathic pain differentially affects emotional behavior, which is in accordance with previous observations in human subjects, both in experimentally induced pain and in chronic pain conditions. Additionally, our results demonstrate that the cognitive function deterioration associated with unilateral neuropathic chronic pain conditions is also differentially affected.
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Comparative Study
Predictors of postoperative movement and resting pain following total knee replacement.
This study determined preoperative predictors of movement and resting pain following total knee replacement (TKR). We hypothesized that younger patients with higher preoperative pain intensity, pain sensitivity, trait anxiety, pain catastrophizing, and depression would be more likely to experience higher postoperative movement pain than older patients with lower scores on these variables prior to surgery, and that predictors would be similar for resting pain. Demographics, analgesic intake, anxiety, depression, pain catastrophizing, resting pain, movement pain (ie, during active knee range of motion), and quantitative sensory tests were performed preoperatively on 215 participants scheduled for a unilateral TKR. ⋯ These results suggest that patients with higher preoperative pain and depression are more likely to have higher pain following TKR, and younger patients may have higher resting pain. Cutaneous pain sensitivity predicted movement pain but not resting pain, suggesting that mechanisms underlying movement pain are different from resting pain. Aggressive management of preoperative pain, pain sensitivity, and depression prior to surgery may facilitate postoperative recovery.