摘要:

The anti-amnesic effects of dynorphins on β-amyloid peptide-(25–35)-induced impairment of learning and/or memory in mice were investigated using a Y-maze task and a passive avoidance test. Administration of β-amyloid peptide-(25–35) (βAP(25–35); 8.2 nmol, i.c.v.) 7 and 14 days before behavioral tests induced a decrease in both alternation behavior and latency in passive avoidance tests. Dynorphin A-(1–13) and A-(2–13) (0.5 and/or 1.5 nmol, i.c.v.) 30 min before behavioral tests improved the β-amyloid peptide-(25–35)-induced impairment of alternation performance and shortened the step-down latency. Nor-binaltorphimine (4.9 nmol, i.c.v.) partially blocked the effects of dynorphin A-(1–13), but not A-(2–13). These results indicate that dynorphin A-(1–13) and A-(2–13) improve amnesia induced by βAP-(25–35) via not only kappa opioid receptors, but also by non-opioid mechanisms.

ISSN:0959-4965    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

The present study used c-Fos expression to examine cellular activity in cholinergic regions in the basal forebrain (BF) following enforced waking and recovery sleep. Cholinergic cells within the vertical and horizontal limbs of the diagonal band of Broca (VDB and HDB, respectively) showed significantly higher c-Fos immunoreactivity after prolonged waking than after recovery sleep. Cholinergic cells within the medial septal nucleus (MS), however, showed no change in c-Fos expression under these conditions. Consistent with our previous findings, c-Fos immunoreactivity in the ventral lateral preoptic area (VLPO) was increased after 1–2 h of recovery sleep compared with enforced waking. These results indicate state-specific effects on transcription and subsequent protein expression in cell populations associated with behavioral state and further show that the HDB, VDB and VLPO are good candidates for the further study of intracellular events associated with sleep and wakefulness.

ISSN:0959-4965    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

High frequency stimulation (HFS) of the subthalamic nucleus (STN) can partially alleviate motor symptoms in patients with Parkinson's disease (PD). However, the mechanism of action of HFS is incompletely understood. We investigated the effect of HFS (130 Hz) and low frequency stimulation (LFS, 20 Hz) of the STN on striatal dopaminergic transmission and metabolism usingin vivomicrodialysis in anaesthetized and freely moving rats. While LFS had no effect, HFS of the STN produced a delayed, stable and intensity-dependent increase of extracellular dopamine metabolites. Striatal extracellular levels of dopamine and 5-HIAA were not influenced by HFS or LFS in the present experimental paradigm. We conclude that HFS of the STN influences striatal dopaminergic metabolism in naive, nonlesioned rats.

ISSN:0959-4965    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

The segmental trisomy Ts65Dn mouse is a novel model of Down syndrome (DS). The purpose of this study was to measure brain levels ofmyo-inositol (mI), N-acetylaspartate (NAA), and other metabolites in Ts65Dn mice using in vivo 1H magnetic resonance spectroscopy (MRS), and to determine whether lithium (Li) treatment alters brain mI level. The ratio of mI over total creatine (Cr), mI/Cr, was significantly elevated (mean change +38%), while NAA/Cr was significantly decreased (mean change −18%) in Ts65Dn mice (n= 5) compared with control mice (n= 7). This is consistent with 1H MRS findings in DS human adults. Brain mI/Cr of the entire sample group (n= 12) was reduced (mean change −15%) following Li treatment, supporting the Li-induced mI depletion hypothesis.

ISSN:0959-4965    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

The propagation of single impulses at axonal branch points and widenings was computed numerically. Previous computational studies have held that an action potential propagates across an unmyelinated axonal branch point with diameter-dependent lowered likelihood, such that increasingly complex arborizations could eliminate propagating information. This result is counterintuitive to the principle of information divergence within neuronal circuits. The present study re-examined this result. The boundary conditions at a branch point were extracted from a physical analog circuit with actual branches. The main results were that impulse propagation was reliable past branch points and widenings, and that conduction velocity changed spatially as a function of fiber geometrical inhomogeneity.

ISSN:0959-4965    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Retinoic acid (RA) is a vitamin A derivative that has been well documented to be involved in cell differentiation. Using RNA fingerprinting by arbitrarily primed PCR, we have previously identified a number of transcripts that are regulated during RA-induced neuronal differentiation of embryonal carcinoma NT2/D1 cells. DEAD box protein p72is one of the clones found to be down-regulated following treatment with RA. To further investigate the regulation of p72, the mRNA expression of p72in various neuronal cell lines and primary neuronal cultures was examined. Transcripts of p72were reduced in differentiated PC12 and IMR-32 cells but not in SH-SY5Y cells. Partial cDNA fragments of p72were isolated from rat and chick for the systematic analysis of p72 expression in different adult tissues and developmental stages. While prominent expression of p72was observed in brain and testis, the expression was down-regulated in brain, muscle and liver during development. Taken together, our findings provide the first demonstration on the spatial and temporal expression profile of p72in rat and chick tissues which is consistent with a role of p72during early development.

ISSN:0959-4965    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Binding of adenosine to neuronal adenosine receptors activates a signal transduction pathway (the adenosine mechanism), leading to a temporary ischemic tolerance. We have demonstrated before that induction of this mechanism in primary rat neuronal cultures, by activation of adenosine receptors, or by activation of protein kinase C (PKC), confers a wide time window of ischemic tolerance, lasting up to 72 h, the early (immediate) part of which depends on opening of KATPchannels (glibenclamide sensitive). Here we demonstrate that the entire duration of the ischemic tolerance conferred by activation of the adenosine mechanism depends on opening of the KATPchannels. Thus, opening of the KATPchannels appears to be a mandatory step in the adenosine mechanism, leading to the creation of the wide time window of ischemic tolerance.

ISSN:0959-4965    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Olfactory bulb ensheathing cell (OBEC) transplants promoted axonal regeneration in the spinal cord dorsal root entry zone and in the corticospinal tract. However, OBECs failed to promote abducens internuclear neuron axon regeneration when transplanted at the site of nerve fibre transection. In experiments performed in both cats and rats, OBECs survived for up to 2 months, lining themselves up along the portion of the regrowing axons proximal to the interneuron cell body. However, OBECs migrated preferentially towards abducens somata, in the direction opposite to the oculomotor nucleus target. OBECs seem to promote nerve fibre regeneration only where preferred direction of glial migration coincides with the direction of axonal growth towards its target.

ISSN:0959-4965    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

In the freshwater planarian Dugesia japonica, which belongs to the most primitive metazoan phylum, serotonin (5-hydroxytryptamine) was detectable by both immunohistochemistry and high-performance liquid chromatography (HPLC) with florometric detection. Immunohistochemical studies showed that serotonin was localized primarily in the cephalic ganglion (brain), in the main nerve cords extending posteriorly from the brain and in the commissure axons connecting the main nerve cords. HPLC with fluorometric detection analysis revealed that the serotonin levels of planarians maintained under a 12:12 h light:dark cycle showed significant diurnal variations with a trough in the middle of the dark phase. In constant darkness, the serotonin levels gluctuated with a circadian rhythm. These results demonstrate the existence of a circadian timekeeping mechanism in the planarian.

ISSN:0959-4965    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

We investigated the properties of small cells in the vomeronasal sensory epithelium of adult rats. The sensory neurons in the sensory epithelium were stained by antibodies to Gi2αand Goαin their cell bodies and dendrites, while the small cells, which formed a cluster in the epithelium, were not stained at all. Voltage-activated inward currents were not detected by patch-clamp recordings, but outward currents were induced by the application of voltage step pulses. These results suggest that the small cells are different from the vomeronasal sensory neurons. Bromodeoxyuridine (BrdU) labeling indicated that dividing cells existed in the cluster of small cells.

ISSN:0959-4965    

出版商:OVID    

年代:2000

数据来源: OVID