摘要:

THERE is no unifying hypothesis to account for the anatomical distribution of neuropathology, the involvement of β-amyloid precursor protein (βAPP) and the role of increasing age in triggering the Alzheimer disease process. We report here that layer II pre-α neurones in transento-rhinal and entorhinal cortex contain more βAPP immunoreactivity than other cortical neurones in normal individuals. This immunoreactivity increased in the early stages of Alzheimer's disease and was lost as the disease progressed. These neurones are known to undergo genetically programmed re-sprouting and synaptogenesis during the fifth and sixth decades of life. We hypothesize that these phenomena are related and that the Alzheimer's disease process originates in entorhinal cortex neurones due to the enhancement of their normally high content of βAPP during age-related resprouting.

ISSN:0959-4965    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

GALANIN, oxytocin and cholecystokinin (CCK) are peptides that influence feeding behaviour. Galanin has been found to stimulate food intake and oxytocin and CCK have been suggested to be satiety agents. The present study was performed in order to investigate if galanin influences the secretion of oxytocin and CCK as a possible indication of a functional relationship between these peptides with respect to their influence on feeding behaviour. Galanin (0.1 and 1 μg) was administered intracerebroventricularly (i.c.v.) and intraperitoneally (i.p.) to anaesthetized rats and blood samples were collected 20 and 60 min after administration. Plasma levels of oxytocin and CCK were measured with radioimmunoassay. Galanin, 0.1 and 1 μg, caused a significant decrease in oxytocin levels after 60 min, both when administered i.c.v. and i.p. In contrast, CCK levels increased following i.c.v. and also i.p. galanin. The possible mechanisms by which galanin causes a decrease in oxytocin and an increase in CCK levels are discussed.

ISSN:0959-4965    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

A PREVIOUS study has shown that the acoustic responsiveness of reticulospinal neurones in the caudal pontine reticular nucleus (PnC) is reduced by glutamate antagonists. It was postulated that the acoustic startle response is mediated by glutamate receptors on PnC-neurones. In the present study, we tested this hypothesis by local microinjections of different glutamate antagonists into the PnC of unrestrained awake rats. In order to differentiate the drug effects on the head and body startle responses, we measured the head startle response electromyographically, and the body startle response in a ballistic chamber. Both the AMPA/kainate and the NMDA receptor antagonists reduced both components of the startle response dose-dependently. We conclude that both subtypes of iono-tropic glutamate receptors in the PnC are relevant for the acoustic startle response in rats.

ISSN:0959-4965    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

To investigate the role of glutamate receptor subtypes in spinal transmission of nociceptive cutaneous and muscular afferents, nociceptive responses of WDR neurones in laminae IV–VI of the dorsal horn produced by noxious cutaneous and muscular stimulation were tested in the cat. With microelectrophoretic administration of the NMDA receptor antagonists, 2-amino-5-phosphonovalerate (APV) and ketamine, cutaneous nociceptive responses were preferentially reduced by more than 50%. In contrast, the non-selective excitatory amino acid receptor antagonist kynurenate (Kyn) markedly reduced both cutaneous and muscular nociceptive responses. The difference between APV- and Kyn-induced reductions of muscular nociceptive responses is statistically significant (X2-test,p< 0.01). The results suggest that NMDA and non-NMDA receptors preferentially mediate transmission of nociceptive information originating in skin and muscle, respectively.

ISSN:0959-4965    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

THE effect of nucleus raphe magnum (NRM) stimulation on the abnormal activity of lumbar dorsal horn neurones in rats with a chronic nerve constriction injury was studied. Neurones on the two sides of the spinal cord were extracellularly recorded in anaesthetized and curarized preparations. The neurones on the side ipsilateral to the injury showed a spontaneous firing frequency higher than that of the opposite intact side (25.8 ± 1.9 spikes s-1vs4.5 ± 1.3 spikes s-1). The hyperactivity was reduced to a mean value of 9.3 ± 1.3 spikes s-1by NRM stimulation using parameters able to selectively inhibit the noxiously evoked neuronal responses on the intact side. The results indicate that the hyperactivity is a phenomenon related to chronic pain that may be modulated by the endogenous pain control system.

ISSN:0959-4965    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

A DILUTE solution of formalin (20 μ1 of 10% formalin) was injected subcutaneously in the dorsal right hind paw of the naked mole-rat. The injection of the dilute formalin produced two periods of pain behaviour, the early (0–5 minutes) and the late phase (25–60 minutes). These were quantified as the total time spent licking the injected paw. Codeine phosphate (10, 25 or 50 mg kg-1) significantly reduced pain behaviour in both the early and late phase. Codeine administration also induced aggressive, hyperactive behaviour and motor impairment that was nalox-one (2 mg kg-1) reversible. Naproxen (200 mg kg-1) and dexamethasone phosphate (30 mg kg-1) significantly reduced licking activity in the late phase only.

ISSN:0959-4965    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

THE proportion of large dense-core vesicles (LDCVs) in motor nerve terminals of the rat biceps brachialis muscle was evaluated from embryonic day 20 to 4 weeks postpartum as well as in the adult. A progressive decrease was observed up to 3 weekspostpartumwhen maturation of the endplates is achieved. Differences compared with the adult were no longer significant at 4 weekspostpartum. Three types of LDVCs, classified according to their size and the core density, were detected. Their relative proportion did not vary significantly during the period of life examined. The high proportion of LDCVs during early development and their persistence at a low level in the adult suggest that they might play a role in the maturation and maintenance of the endplates.

ISSN:0959-4965    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

THE low-affinity nerve growth factor (NGF) receptor (LNGFR) binds the neurotrophins NGF, brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) with similar affinities. Here we report on the ability of NT-3 to regulate the expression of the LNGFR in C6 glioma cells. LNGFR-like immunoreactivity (LNGFR-IR) was examined in C6 cells treated for 16 h with NT-3 and exposed to the antibody 192-IgG followed by immunoglobulins conjugated with colloidal gold by means of ultra-structural morphometric analysis. Untreated C6 cells exhibited some positive LNGFR-IR, while C6 cells treated with NT-3 displayed significantly increased (2.3fold) LNGFR-IR. The increase in LNGFR protein was accompanied by a greater quantity of LNGFR mRNA in NT-3-treated cells. Thus, LNGFR can be upregulated by the structurally related neurotrophin NT-3.

ISSN:0959-4965    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

USINGin situhybridization histochemistry and immunocytochemistry the induction of immediate early genes (IEGs) was studied in the rat superior cervical ganglion (SCG) after deafferentation, axotomy and sialectomy (removal of the submandibular gland). Control SCGs showed very low levels of IEGs, whereby Fos proteins were found in 1% and Jun protein in 6% of neurons, but not in non-neuronal cells. Denervation and axotomy induced C-fos, NGFI-A, c-jun, junB andjunD mRNA expression for up to 6 days in non-neuronal cells, whereas in sympathetic neurons the expression of only c-junmRNA was induced after axotomy and sialectomy. The induction of Fos and Jun proteins by neuronal injury was demonstrated by immunocytochemistry. The results indicate that neuronal injury induces IEGs mainly in non-neuronal cells and that in neurons only c-junis induced after axotomy. It is hypothesized that the induction of IEG other than c-junin neurons after brain injury is an indirect event unrelated to the neuronal response to injury.

ISSN:0959-4965    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

ANIMALS and humans display a constellation of behavioral and neurochemical signs after termination of psychostimulant administration. Amphetamine withdrawal could involve the dopaminergic systems that are thought to underlie psychostimulant rewarding effects, and may thus conceivably alter expression of key genes for dopaminergic transmission, including those encoding tyrosine hydroxylase (TH), the membrane dopamine transporter (DAT) and the synaptic vesicle amine transporter (SVAT). Withdrawal from 7.5 mg kg-1i.p. amphetamine (b.i.d. for a two week duration) yields no significant changes in rat DAT mRNA. TH mRNA levels are modestly enhanced over the same week of withdrawal, during which dopamine levels and behavioral novelty responses are both depressed. SVAT expression is significantly blunted following chronic amphetamine treatment. Altered TH and/or SVAT gene expression might contribute to restoring normal function to neurons “withdrawing” from amphetamine treatments.

ISSN:0959-4965    

出版商:OVID    

年代:1993

数据来源: OVID