Neuroscience letters
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Neuroscience letters · Dec 2009
Effect of propofol on the levels of neurotransmitters in normal human brain: a magnetic resonance spectroscopy study.
Though widely used in anesthesia for many years, the mechanism underlying propofol anesthesia on human is not clear. Animal studies have already demonstrated that propofol functioned mainly by affecting neurotransmitters release. In our study, 10 healthy volunteers ranging from 20 to 40 years old were enrolled. ⋯ There was no obvious change in Cr levels in any statuses or brain regions. Our results indicate that propofol has an impact on the levels of neurotransmitters such as NAA, GLU, GABA and Cho in normal human brain. During propofol anesthesia, enhancement of inhibition or suppression of excitation may each play key roles in different brain regions.
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Hand dominancy (i.e. handedness) is a factor that should be considered for further characterizing individual variations in sensitivity to pain. The aim of the present study was to examine the contribution of handedness and gender to sensitivity to tonic cold pain in healthy subjects. Participants were 109 healthy volunteers (52 males and 57 females), of whom 65 were right-handed and 44 left-handed. ⋯ No significant differences were found among the left-handed males or among the females. The results provide further evidence that handedness is one vital feature that should be considered more often when designing a psychophysical study. This may lead towards improving the translation of laboratory research findings to the clinical setting.
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Neuroscience letters · Dec 2009
Acute bladder inflammation differentially affects rat spinal visceral nociceptive neurons.
The present investigation examined the effect of inflammation produced by intravesical zymosan on spinal dorsal horn neuronal responses to urinary bladder distension (UBD). Extracellular single-unit recordings of neurons excited by UBD were obtained in spinalized female Sprague-Dawley rats. Neurons were classified as Type I-inhibited by heterotopic noxious conditioning stimuli (HNCS) or as Type II-not inhibited by a HNCS. ⋯ No significant changes were noted in neuronal activity in control experiments. Inflammation differentially affects subpopulations of spinal dorsal horn neurons excited by UBD that can be differentiated according to the effect of HNCS. This results in an altered pattern of spinal sensory transmission that may serve as the mechanism for the generation of visceral nociception.
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Neuroscience letters · Dec 2009
NMDA receptors are involved in upstream of the spinal JNK activation in morphine antinociceptive tolerance.
N-methyl-d-aspartate (NMDA) receptors and c-Jun N-terminal kinase (JNK) have been shown to be involved in morphine antinociceptive tolerance. However, whether chronic morphine-induced activation of the spinal JNK is NMDA receptor-dependent is unknown. The present study investigated the link between the spinal NMDA receptor NR2B subunit and the JNK activation during morphine antinociceptive tolerance in rats. ⋯ SP600125, a selective inhibitor of JNK, significantly attenuated morphine tolerance. MK-801, a noncompetitive NMDA receptor antagonist, not only suppressed morphine antinociceptive tolerance and the increase in NR2B, but also reduced the spinal JNK activation induced by chronic morphine treatment. These findings demonstrated for the first time that NMDA receptor-dependent activation of the spinal JNK contributes to morphine antinociceptive tolerance and that MK-801 attenuates morphine tolerance partly due to its inhibition on the spinal JNK activation.