摘要:

TO examine the specific roles of group I metabotropic glutamate receptors (mGluRs) in nociceptive processing, we examined the effects of intrathecal (i.t.) treatment with antibodies raised against the C-terminals of mGluR1and mGluR5in various rat pain models. The effects of anti-mGluR1IgG and anti-mGluR5IgG were assessed in a model of persistent pain induced by intrathecal administration of the mGluR1/5agonist DHPG, as well as in models of heat pain (plantar test), chemical pain (formalin test) and neuropathic pain. DHPG-induced spontaneous nociceptive behaviours (SNB) were significantly attenuated by i.t. treatment with either anti-mGluR1IgG (30 μg) or anti-mGluR5IgG (10 and 3 0μg). Neither anti-mGluR1IgG (30 μg) nor anti-mGluR5IgG (30 μg) significantly increased response latencies to noxious heat in the plantar test, compared with anti-rat IgG (control IgG). Moreover, neither antibody (3 0μg) significantly reduced formalin pain scores as compared to control IgG. However, i.t. treatment with anti-mGluR1IgG (30 μg) or anti-mGluR5IgG (30 μg) significantly reduced cold hyper-sensitivity exhibited 8 days after constriction injury of the sciatic nerve, supporting the contention that group I mGluRs play a role in the development of neuropathic pain. Because these antibodies were effective against neuropathic pain, and not acute heat or chemical noxious stimuli, these results suggest that mGluRs are involved in nociceptive processing in chronic pain states rather than signaling acute noxious stimuli, and that DHPG-induced pain may be mediated by similar mechanisms as neuropathic pain.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

BRAIN neuropeptide Y (NPY) subtype-5 (Y5 receptor) mRNA expression in lean (+/+) and obese (ob/ob) C57Bl/6 mice was examined using a non-radioactivein sit uhybridization detection method. Significant decreases in Y5 receptor mRNA expression were found in the ventromedial, dorsomedial and arcuate hypothalamic nuclei, midline thalamic nuclei, piriform, cingulate and retrosplenial granular cortices of the obese mouse brain. There were minor changes in the amount of Y5 receptor mRNA expression in the hippocampal formation and medial habenular nucleus. Results indicated that Y5 receptor mRNA expression is downregulated in hereditary obese (ob/ob) mice. This is possibly due to over-expression of hypothalamic NPY which occurs in this phenotype.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

TO elucidate synaptic interactions between expiratory (Exp) and other respiratory neurons in the ventrolateral medulla of brain stem–spinal cord preparations from newborn rats, we analyzed postsynaptic potentials in Exp and a subclass of inspiratory (Insp) neurons using whole-cell recordings. About 72% of the Exp neurons (Exp-p-i) showed Clγ-dependent synaptic inhibition during the Insp and pre/post-Insp phases, corresponding to the active phase of the Insp and pre-inspiratory (Pre-I) neurons, respectively. The other 28% neurons (Exp-i) received Cl−-dependent inhibition during the Insp phase only. Some Insp neurons showed reversed IPSPs during the active phase of Exp-p-i after Cl−loading. We suggest the existence of inhibitory connections from Pre-I and Insp to Exp and from Exp to Insp neurons. Basic synaptic connections among respiratory neurons similar to those in intact adult mammals may already exist in newborn rats.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

EVENT related potentials (ERP) were recorded from 29 electrode positions in 10 normal subjects while they performed a simplified version of the Wisconsin Card Sorting Test (WCST). The design focused on ERP differences between early and late trials within each WCST series. Topographic and dipole analyses confirmed the reliability of two ERP signs: one conspicuous mid-parietal P3b wave and one asymmetrical frontal-temporal component. A three-dipole model accounted for these ERP signs with > 90% accuracy even in individual subjects, and suggests a sub-second activation of temporal-parietal and medial temporal association areas during card sorting. The WCST-related P3b wave is proposed to reflect working memory operations such as template matching and template formation during card sorting.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

FRONTAL cortical damage can lead to changes in affective aspects of personality. However, the difficulty of dissociating such abnormalities from cognitive disorders has overshadowed most previous findings. Regional cerebral blood flow (rCBF) was measured with positron emission tomography (PET) while normal subjects were assessing facial attractiveness. Two left frontal regions showed a significant increase in rCBF while assessing facial attractiveness. The increased rCBF in the left anterior frontal cortex correlated with the overall percentage of assessments of a face as unattractive, while that in the left fronto-temporal junction correlated with the percentage of assessments of a face as attractive. These findings provide direct evidence that the left frontal regions are engaged in the assessment of facial attractiveness.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

LEVELS of dehydroepiandrosterone (DHEA) and its sulfated derivative (DHEA-S) decline during aging and reach even lower levels in Alzheimer's disease (AD). Previously published effects of DHEA and DHEA-S on unchallenged neuronal survival led us to test them in an excitotoxicity paradigm. While DHEA-S protected hippocampal neurons against glutamate, little protection was observed with equivalent doses of DHEA itself. This differential neuroprotection was consistent with the ability of DHEA-S (but not DHEA) to elevate a κB-dependent transcription factor activity, a phenomenon we previously have connected with neuroprotection. Furthermore, suppression o fκB DNA-binding by ‘decoy’ oligonucleotides blocked the neuroprotective activity of DHEA-S. These findings imply that age-related declines in the availability of DHEA-S could exacerbate neurotoxicity, and the data suggest that therapeutic gains may be obtained with pharmacological manipulation o fκB-dependent transcription in neurons.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

THE cortical organization of executive control was investigated using event-related potentials (ERPs). ERPs were collected while subjects performed a go/no go task that required response inhibition. First, around 26ms after stimulus onset, an effect of response inhibition on ERPs was observed over inferior prefrontal areas. Generators in these regions were confirmed by source analysis. Later, between 300–60 ms after stimulus onset, a left lateralized fronto-central ERP effect was found which differed in topography from a non-specific effect of task difficulty. Source analysis indicated that generators in anterior cingulate and left premotor areas also contributed to this effect. Orchestrated activation of prefrontal areas and the anterior cingulate subserves executive function whereas relatively late activity of the left premotor cortex is involved in motor control.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

A study was made of the borderline between the physiological representations of the digits (D2, D3 and D4) and sinus whiskers in the rat primary somatosensory cortex after a contralateral infraorbital nerve crush. Following the injury, the physiological representation of the digits of the contralateral forepaw extended posterolaterally, occupying the anterolateral part of the whisker region (posteromedial barrel subfield). The extended physiological representation of the digits, though somewhat shrunken, remained after the reappearance of whisker-evoked responses, forming an overlapping area between the obligate digit and whisker representations. The findings emphasize the importance of afferent inputs in modulating cortical organization, but show that a reversible change in a sensory input (nerve damage) does not result in a perfectly reversible change in cortical representation.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID