Neuroscience letters
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Neuroscience letters · Apr 2003
Comparative StudyThe influence of semantic priming on event-related potentials to painful laser-heat stimuli in migraine patients.
We investigated the effects of different semantic primes on the processing of painful stimuli in migraine patients. For prime stimuli, descriptors of three categories were used: somatosensory pain-related, affective pain-related, and neutral adjectives. While migraine patients (n = 17) processed these primes, a painful laser-heat stimulus was applied to the dorsum of the left hand. ⋯ Within the group of migraine patients, LEP amplitudes at 300 ms post laser stimulus and N2-P2 peak-to-peak amplitudes were significantly enlarged when applied while subjects processed pain-related as compared to non-pain-related primes, i.e. patients showed a pattern of priming effect similar to that of the control group. Additionally, patients recognised more affective words than control subjects, and affective pain-related primes tended to enhance the P2 amplitude of LEP more than somatosensory pain-related primes. It is suggested that pain-related semantic primes might pre-activate neural networks subserving pain memory and pain processing.
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Neuroscience letters · Apr 2003
Subjective sleepiness correlates negatively with global alpha (8-12 Hz) and positively with central frontal theta (4-8 Hz) frequencies in the human resting awake electroencephalogram.
Subjective sleepiness is part of the system controlling the decision to go to sleep in humans. Extended periods of waking lead to increased sleepiness, as well as to changes in cortical electroencephalogram (EEG) during waking. ⋯ We found: (1). strong negative correlations of alpha (8-12 Hz) power with subjective sleepiness at all scalp locations, suggesting a negative association between sleepiness and general cortical activation; and (2). positive correlations of theta (4-8 Hz) power with subjective sleepiness with a focus on frontal locations, suggesting additional location specific associations between sleepiness and cortical activation. These findings support the notion that sleepiness is directly represented in the awake EEG.
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Neuroscience letters · Mar 2003
Deletion of the preprotachykinin A gene in mice does not reduce scratching behavior elicited by intradermal serotonin.
Itch is thought to be signaled by a sub-population of pruritogen-selective C-fiber primary afferents. To assess a possible role of the neuropeptide, substance P (SP), in the central neurotransmission of itch, we investigated itch-related scratching behavior elicited by intradermal injection of serotonin (5-HT; 0.03-0.3%) in normal mice (wildtype, WT) and knockout mice (KO) with deletion of the preprotachykinin A gene. ⋯ There were no significant differences in the numbers or durations of scratching bouts between WT and KO groups, although KO mice exhibited numerically more spontaneous and 5-HT-evoked scratching. It is concluded that either SP is not involved in the central neurotransmission of itch-related scratching behavior in this strain of mouse, or that compensatory developmental changes in the KO mice allow itch-related signaling.
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Neuroscience letters · Mar 2003
Clinical Trial Controlled Clinical TrialSexual dimorphism in very low dose nalbuphine postoperative analgesia.
In recent studies we demonstrated that the analgesic effect of the kappa-like opioids is significantly greater in women, that low dose nalbuphine (5 mg) produces profound anti-analgesia (i.e. enhances pain) in men, and that addition of a low dose of the non-selective opioid receptor antagonist naloxone (0.4 mg) to nalbuphine (5 mg) abolishes the sex difference and results in significantly enhanced analgesia in both sexes. To further delineate the dose-dependent analgesic and anti-analgesic effects of nalbuphine, the present study evaluated the effect of a lower dose of nalbuphine (2.5 mg), with and without naloxone, on dental postoperative pain. ⋯ Thus, the anti-analgesic effect of nalbuphine, present in both sexes at the 5 mg dose disappears at the lower dose of nalbuphine. In addition, the mild analgesia in women produced by this lower dose of nalbuphine is antagonized by naloxone.
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Neuroscience letters · Mar 2003
Evaluation of indices of skeletal muscle contraction in areas of referred hyperalgesia from an artificial ureteric stone in rats.
This study examined indices of skeletal muscle contraction in a rat model of referred muscle hyperalgesia from artificial ureteric calculosis [left oblique muscle (OE) for ipsilateral stone]. In specimens from the left versus right OE of stone-implanted female rats, a significant increase was found in membrane fluidity (P<0.01) and Ca(2+)-ATPase activity (P<0.0001) and a significant decrease in 3H-ryanodine binding (P<0.0001) and in I band length/sarcomere length ratio (contraction index) (P<0.01). The increase in Ca(2+)-ATPase activity was directly and significantly related to the number of rats' ureteral 'crises' (P<0.02). The results indicate a state of contraction in the hyperalgesic muscle, whose extent correlates to the algogenic activity of the ureteral stone.