Neuroscience letters
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Neuroscience letters · Aug 2002
Deep brain stimulation of subthalamic neurons increases striatal dopamine metabolism and induces contralateral circling in freely moving 6-hydroxydopamine-lesioned rats.
Deep brain stimulation (DBS) of the subthalamic nucleus (STN) alleviates Parkinson's disease (PD) symptoms. Although widely used, the mechanisms of action are still unknown. In an attempt to elucidate those mechanisms, we have previously demonstrated that STN-DBS increases striatal extracellular dopamine (DA) metabolites in anaesthetized rats. ⋯ STN-DBS induced an increase of striatal DA metabolites in awake, freely moving animals. Furthermore, we observed concomitant contralateral circling behaviour. Taken together, these results suggest that STN-DBS could disinhibit (consequently activate) substantia nigra compacta neurons via inhibition of gamma-aminobutyric acid-ergic substantia nigra reticulata neurons.
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Neuroscience letters · Aug 2002
Attentional modulation of human pain processing in the secondary somatosensory cortex: a magnetoencephalographic study.
The influence of attention on the processing of pain in the secondary somatosensory cortex (SII) was analyzed using magnetoencephalography in response to painful infra-red heat stimuli applied to the left hand in six male healthy subjects, aged 22-28 years. Three experimental paradigms were chosen to deliver attention dependent results under comparable levels of vigilance. ⋯ In contrast, further increase of attention from mid-level to high was not accompanied by an additional enhancement of SII activity. It therefore is concluded that activation patterns of SII follow a saturation function which cannot be enlarged by maximizing the relevance of the painful stimuli.
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Neuroscience letters · Jul 2002
Nitric oxide production in hypothalamus of 2-deoxy-D-glucose-treated and food deprived mice.
Nitric oxide (NO) has been suggested to be involved in the regulation of food intake. In the present study, NO metabolite (nitrite and nitrate, NOx) levels in the hypothalamus were determined in hyperphagic mice. In normal mice, NOx levels were higher in the hypothalamus than those in frontal cortex. ⋯ NOx concentration in the hypothalamus decreased in 48 h-food deprived mice. In the frontal cortex, neither 2-DG nor food deprivation affected NOx levels. These results suggest that NO production in the hypothalamus does not increase in 2-DG-elicited hyperphagia and that food deprivation reduces hypothalamic NO, probably by inhibiting NO synthase.
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Neuroscience letters · Apr 2002
Clinical Trial Controlled Clinical TrialThe addition of glyceryltrinitrate to capsaicin cream reduces the thermal allodynia associated with the application of capsaicin alone in humans.
The aim of this study was to determine whether topical application of capsaicin cream causes thermal allodynia and the extent to which this is attenuated by the addition of glyceryltrinitrate (GTN). This was a double blind placebo controlled study of 40 consenting adult subjects. Each of four cream combinations (GTN, capsaicin, GTN/capsaicin and vehicle) were applied to the subjects with at least a 1 day interval between each application. ⋯ Thermal allodynia is usually apparent when warm water is applied to skin containing capsaicin. The thermal allodynia caused by the topical application of capsaicin was significantly reduced by the addition of GTN. The addition of GTN to capsaicin cream significantly reduces the thermal allodynia associated with the application of capsaicin cream alone.
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Neuroscience letters · Apr 2002
Increased production of nitric oxide stimulated by interferon-gamma from peripheral blood monocytes in patients with complex regional pain syndrome.
This study examines immediate nitric oxide (NO) release from monocytes following interleukin-1beta (IL-1beta), interferon-gamma (IFN-gamma), and tumor necrosis factor-alpha (TNF-alpha) challenge in patients with complex regional pain syndrome (CRPS). Study patients exhibited the following: (1), mechanical allodynia; (2), evidence of either vasomotor or sudomotor disturbance; and (3), concordant painful allodynia documented with quantitative sensory testing that was temporarily abolished with sympathetic block. ⋯ Subjects with CRPS exhibited a statistically significant increase in NO release in response to IFN-gamma (P<0.012) compared with controls. The NO responses to IFN-gamma in excess of NS (P<0.025) and as the ratio IFN-gamma/NS (P<0.022) were also significantly increased.