摘要:

THE constitutive and heat-inducible expression of HSP105 was investigated in newborn mouse brain cell cultures by Northern blotting, Western blotting and immunocytochemistry. HSP105 was expressed most abundantly in the brain among the various tissues examined. HSP105 mRNA and protein were both present at substantial levels in brain cell cultures under unstressed conditions and up-regulated greatly during 3–4 8h following exposure to heat stress (4 3°C/2 0min). HSP105 was expressed in nearly all neurons, oligodendrocytes, microglia and astrocytes with its location of both cytoplasmic and nuclear regions under unstressed and heatstressed conditions. HSP105 expression was significantly down-regulated in astrocytes following treatment with IL-β or TNF-α (5 0ng/ml for 6 days), both of which are known growth-stimulatory cytokines for astrocytes. These results indicate that HSP105 is constitutive and heat-inducible HSP in neurons and glial cells in which its expression is under the control of both stressful stimuli and growth-regulatory factors.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

THE NMDA receptor antagonist phencyclidine (PCP) has low micromolar affinity for the 5-HT reuptake site, but it is uncertain whether PCP blocks 5-HT reuptake when given systemically to rats in behaviourally stimulating doses. We here report for the first time that systemically administered PCP (5 mg/kg, s.c.) increases extracellular 5-HT levels in the rat medial prefrontal cortex (to 322%) and dorsal hippocampus (to 233%). Increases were found also when citalopram (μM) was included in the perfusion medium (to 184 and 180%, respectively). Extracellular 5-HIAA concentrations increased during both conditions, and extracellular GABA decreased in the dorsal hippocampus. It is concluded that systemic PCP treatment elevates extracellular 5-HT levels, probably through mechanisms other than a blockade of 5-HT reuptake

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

FENFLURAMINE is an amphetamine analogue which has been widely used in the treatment of obesity. In rodents, non-human primates, and humans, fenfluramine is associated with some indices of neurotoxicity, as well as pulmonary hypertension and cardiac valve pathology. In the present study, d-fenfluramine was found to be cytotoxic to the serotonin (5-HT) transporter (5-HTT) expressing human placental choriocarcinoma cells. d-Fenfluramine caused DNA fragmentation and apoptosis. Apoptosis was not observed after the 5-HTT had been blocked by fluoxetine, indicating that intact 5-HTT function is required for d-fenfluramine to induce programmed cell death. These observations in a human cell line may reflect a possible mechanism associated with the risks of fenfluramine administration in several species, including humans.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

THREE areas of the left hemisphere play different roles in sentence comprehension. An area of posterior middle and superior temporal gyrus shows activation correlated with the structural complexity of a sentence, suggesting that this area supports processing of sentence structure. The lateral anterior temporal gyrus is more activated bilaterally by all sentence conditions than by word lists; thus the function of the area probably does not directly support processing of structure but rather processing of words specific to a sentence context. Left inferior frontal cortex also shows activation related to sentence complexity but is also more activated in word list processing than in simple sentences; this region may thus support a form of verbal working memory which maintains sentence structural information as well as lexical items.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

TWO patterns of appropriately filtered acoustic white noise can be binaurally fused by the human auditory system to extract pitch and location information that is not available to either ear alone. This phenomenon is called dichotic pitch. Here we present a new method for generating more effective and useful dichotic pitch stimuli. These novel stimuli allow the psychophysical assessment of dichotic pitch detection thresholds. We show that dichotic pitch detection is significantly impaired in individuals with developmental dyslexia, as compared to average readers. These results suggest a low-level auditory deficit associated with dyslexia and also demonstrate the potential value of our new dichotic pitch stimuli for assessment of auditory processing.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

THE mechanisms that regulate adenosine release in the brain are not well understood. The present study investigated the hypothesis that individual neurons can generate and release sufficient adenosine to regulate their synaptic inputs. We utilized the whole-cell recording technique to apply enzyme inhibitors and nucleotides directly into the cytoplasm of single rat hippocampal CA1 pyramidal neurons. Cytoplasmic delivery of adenosine induced the release of sufficient adenosine to inhibit excitatory synaptic inputs. However, intracellular delivery of nucleotides and enzyme inhibitors failed to increase adenosine receptor-mediated inhibition. These data suggest that while pyramidal neurons in the hippocampus are capable of releasing large amounts of adenosine into the extracellular space, they do not readily form adenosine from endogenous sources.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

NEURONAL activity in the perirhinal cortex was recorded while rats performed a spatial task on a four arm radial maze. The maze was defined by proximal multisensory cues on the arm surfaces and distal complex visual cues at the surround. During each recording session, rats were run in three conditions: baseline, a condition in which proximal and distal cues were manipulated, and a second baseline. Compared with the activity of hippocampal neurons in the same paradigm, a much smaller proportion of perirhinal neurons exhibited spatial selectivity and perirhinal place fields were larger than hippocampal place fields. Although perirhinal place fields exhibited a high degree of spatial tuning and reliability within a condition, they were not stable across conditions.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

PREVIOUS imaging studies of pain used a block design of prolonged (up to 1 min) noxious stimulation that are not well tolerated and subject to temporal interactions. We describe an adaptation of event-related fMRI to study pain with short duration stimuli. Functional images were acquired with a spiral sequence on a 1.5T GE echospeed MRI system of the thalamus, anterior cingulate, insula and second somatosensory cortex during brief (1–3 s) noxious thermal stimulation of the hand of normal volunteers. An MRI-compatible computerized rating system continuously monitored subjects' pain. Brief pain-related activations were clearly identified in the cortex and thalamus with a hemodynamic delay of 3–6 s. These findings demonstrate that brief stimuli combined with on-line pain ratings can be used to study pain with fMRI.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

MU opioid receptors within the pontine reticular formation contribute to opioid-induced rapid eye movement (REM) sleep inhibition. Mu receptors are coupled to guanine nucleotide binding (G) proteins and this study tested the hypothesis that th μ opioid agonist [D-Ala2,N-Me-Phe4,Gly-ol5]enkephalin (DAMGO) would activate G proteins in rat brain stem nuclei known to regulate REM sleep.In vitroautoradiography of DAMGO-stimulated [35S]GTPγS binding showed that, compared with basal [35S]GTPγS binding, DAMGO significantly increased G protein activation in the nucleus pontis oralis (56.2%), nucleus pontis caudalis (57.3%), laterodorsal tegmental nucleus (75.8%), pedunculopontine tegmental nucleus (72.4%), nucleus locus coeruleus (77.2%) and dorsal raphe nucleus (73.4%). DAMGO stimulation of [35S]GTPγS binding in nuclei regulating REM sleep suggests that opioid-induced REM sleep inhibition involves activation of G proteins.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

MICROGLIAL activation is a prominent feature of affected brain areas in multiple system atrophy. Microglia express proinflammatory peptides, which may be a result of activation of nuclear factor-κB. We investigated the nuclear presence of RelA, the 65kDa subunit of the NF-κB/RelA family in striatum and brain stem of patients with multiple system atrophy. Affected brain areas of patients with multiple system atrophy showed a marked immunoreactivity for nuclear Rel A p65, which was almost exclusively localized in activated microglia. Interestingly nuclear translocation of Rel A was not detected in striatal tissue of controls and Parkinson disease patients. Thus, NF-κB/Rel A complexes may play a role in mediating microglial activation in multiple system atrophy.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID