ISSN:0959-4965    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

UNIT activity was recorded from 96 neurons in the periaqueductal gray (PAG) in response to focal electrical stimulation of the lateral reticular nucleus (LRN) and the nucleus gigantocellularis (NGC), in anesthetized, curarized rats. Consistent with anatomical studies showing direct projections from these nuclei to PAG, short latency excitatory responses (< 5ms) were found in 63 neurons and inhibition of the activity in 28 neurons. Peripheral noxious heat stimulation was effective in altering the activity in 36 of these neurons (38%). The LRN and NGC stimuli inhibited the noxious evoked responses in 26 of these neurons. The inhibition could also be induced when the dorsolateral funiculi (DLFs) were cut. These results indicate that LRN and NGC can have a direct influence on PAG neurons, which are probably involved in the processing of noxious information.

ISSN:0959-4965    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

TRANSFORMING growth factor-β1 (TGF-β1) markedly increased the, mRNA encoding nerve growth factor (NGF) in cultured rat astrocytes in a time- and concentration-dependent manner. The maximal effect of TGF-β1 (a 50-fold increase in NGF-mRNA) was reached after 24 h incubation. The TGF-β-mediated increase in NGF-mRNA results from enhanced transcription as shown in nuclear run-on studies and in transfection assays using the NGF promoter linked to a chloramphenicol acetyltransferase (CAT) reporter gene. TGF-β1 also increased its own expression in astrocytes as well as that of the proto-oncogene c-fos. Intraventricular injection of TGF-β1 resulted in an increase of NGF-mRNA levels in the rat hippocampus (3–4 fold) showing that TGF-β1 is also effective in increasing NGF expression in vivo.

ISSN:0959-4965    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

A RAT monoclonal antibody (OL-1) was obtained byin-vitroimmunization of rat spleenocytes with para-formaldehyde-fixed primary cultured glial cells derived from newborn rat brain and subsequent fusion with a rat myeloma cell line. The antibody secreted by the hybridoma immunostains live rat and mouse oligo-dendrocytes in primary and secondary cultures. The antibody binds specifically to oligodendrocytes and myelin structuresin-situ. Radioimmunolabelling assays with a number of purified glycolipids offer thin layer chromatography separation show that OL-1 antibody binds strongly to sulfatide and to a lesser extent to galactosyl diglyceride.

ISSN:0959-4965    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

Because of anecdotal reports in which ibogaine eliminates opioid withdrawal symptoms in humans, we studied this phenomenon in the rat model. Ibogaine (5,10, 20 and 40 mg kg−1, s.c.) was administered 15min before naloxone (0.5 mg kg−1, s.c.) in morphine dependent rats (3 days after the s.c. implantation of a 75 mg morphine pellet). Of the 12 withdrawal signs scored, the only significant changes observed after ibogaine (compared with vehicle control) was a decrease in grooming (10 mg kg−1) and an increase in teeth chatter (5 mg kg−1). In spite of ibogaine's apparent interaction with several neurotransmitter receptor systems, it does not alleviate opioid withdrawal in this animal model at non-tremor-igenic (5 and 10 mg kg−1) or tremorigenic (20 and 40 mg kg−1) doses.

ISSN:0959-4965    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

THE potential of DuP753, an angiotensin II receptor antagonist, to inhibit the suppressed behaviour of mice in a light/dark aversion test was investigated. The aversive response to the light compartment of the apparatus was reduced (increase in latency to move from the light to the dark compartment and decreases in rears, line crossings and percentage of time spent in the dark compartment) following treatment with DuP753 (0.1–1000 ωg kg-1p.o., 45 min before the test). These results further implicate the modulation of mental function by angiotensin II.

ISSN:0959-4965    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

BY binding to a specific receptor, the drug vesamicol [(-)—trans-2-(4-phenylpiperidino)cyclohexanol] noncom-petitively inhibits acetylcholine active transport into synaptic vesicles. An analog [(±)-trans-5-amino-2-hydroxy-3-(4-phenylpiperidino)tetralin] of vesamicol has been discovered that causes time- (t1= 2.6 min) and temperature-dependent loss of vesamicol binding that is only slowly reversible (t1for recovery = 5.4 h). Assuming a simple two step process of ligand binding followed by a conformational change, an apparent dissociation constant of 4 χ 10-11M can be calculated. Other analogs of the vesamicol family of drugs also display similar high-affinity binding to the receptor in a manner which resembles the time dependent effects of reserpine binding to chromaffin granules.

ISSN:0959-4965    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

THE antiepileptic agents, carbamazepine and phenytoin, suppress seizures in man and convulsant-induced hyper-activity in spinal cord nerve cell cultures. In the present study, we have shown by whole cell recording that carbamazepine, in contrast to phenytoin, blocks N-methyl-D-aspartate (NMDA)-activated membrane currents in cultured neurons in a dose-dependent fashion. The NMDA receptor-activated channel, which is blocked at physiological concentrations of Mg2+at resting membrane potential, can be activated by glutamate in depolarized neurons and thus be involved in epileptogenesis. Therefore, the block of NMDA-evoked membrane currents in cultured neurons may contribute to the clinical effectiveness of carbamazepine.

ISSN:0959-4965    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

NMDA receptor-mediated Ca2+flux was studied in cultured rat retinal ganglion cells and neocortical neurons. Intracellular free calcium ([Ca2+]iwas measured with fura-2 fluorescence imaging. Baseline [Ca2+]iwas 59±5nM. In low [Mg2+]o, 200 ωM NMDA reversibly increased [Ca2+]ito 421 ± 70 nM. This rise in [Ca2+]iwas blocked by the NMDA antagonists APV (200 ωM) or [Mg2+]o(1 ωM), but only slightly inhibited by the non-NMDA antagonist CNQX (10 ωM). Chemical reduction with dithiothreitol (DTT) had no effect on resting [Ca2+]i. However, DTT increased the NMDA-induced rise in [Ca2+]i∼ 1.6-fold; the oxidizing agent dithiobisnitro-benzioc acid (DTNB) reversed this effect. In patch-clamp experiments, DTT increased NMDA-activated whole-cell conductance ∼ 1.7-fold in low and high [Ca2+]o. The Ca2+/ Na+permeability ratio of ∼7 for NMDA channels remained unaltered by chemical reduction. Thus, redox modulation of the NMDA receptor/channel complex results in a dramatic alteration in current magnitude but no change in ionic permeabilities.

ISSN:0959-4965    

出版商:OVID    

年代:1990

数据来源: OVID

摘要:

PREVIOUS studies of the permeation of circulating protein tracers yielded conflicting results in the enteric nervous system. We show that within 5 min of intravenous injection, horseradish peroxidase (HRP) enters all the extracellular spaces of the ganglia and connecting strands of the submucous and myenteric plexuses of the rat's small intestine, including the clefts between neuroglial cells and neurons. The tracer is still there after 10 min, but is nearly all gone 30 min after injection. Enteric neurons, like others with somata in peripheral ganglia, are therefore probably accessible to plasma proteins and to substances with smaller molecules that are protein-bound when circulating in the blood.

ISSN:0959-4965    

出版商:OVID    

年代:1990

数据来源: OVID