摘要:

AbstractNicotine is among the compounds that enter the brain very rapidly (blood‐flow‐limited). It also leaves the brain rapidly; by five minutes, 90% exits, an exit somewhat slower than that of water. In spite of rapid exit, brain levels remain higher than levels in blood over a wide range of blood concentrations. Nicotine enters the fetal circulation from the maternal blood; it enters fetal brain but to a smaller extent than adult brain. Nicotine entry is different from that of amino acid: No interaction of amino acid transport and nicotine could be detected. Most close analogs have no effect on nicotine uptake, but at higher concentrations nicotine uptake is saturable. Nicotine and morphine mutually inhibit each other's uptake. The results suggest an uptake compartment (lipid space) for nicotine shared by morph

ISSN:0360-4012    

DOI:10.1002/jnr.490040202

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1979

数据来源: WILEY

摘要:

AbstractThe rate of incorporation of3H‐leucine into proteins of the synaptic junctional and nonjunctional membranes and synaptic vesicles of rat brain has been examined in control and morphine‐tolerant rats. There are no discernible differences between control and tolerant animals in amount of protein as measured by densitometric tracings of dye‐stained proteins separated by acrylamide gel electrophoresis from the three membrane fractions of whole brain areas. However, there are differences in the turnover of membrane protein: three vesicle protein bands and one junctional‐membrane protein band are significantly more highly labeled, and one junctional‐membrane protein is significantly less highly labeled by3H‐leucine in samples from tolerant rats. Of these, the two junctional‐membrane proteins can be tentatively identified as components of the postsynaptic densities, and one of the vesicle protei

ISSN:0360-4012    

DOI:10.1002/jnr.490040203

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1979

数据来源: WILEY

摘要:

AbstractThe neurotoxicity of RNA‐free lipopolysaccharide (LPS) extracted from Salmonella Typhimurium (SR‐11) was tested at the frog neuromuscular junction using intracellular recording techniques. Spontaneous miniature endplate potential (MEPP) frequency was reduced to 45% of control after 60 minutes in the presence of 10 and 50 μg LPS/ml Ringer's solution. Elevation of extracellular [Ca] to 10 mM converted the MEPP frequency response to a biphasic pattern of early acceleration followed by late depression. Evoked endplate potentials (EPPs) were reduced in quantal content until phasic release of transmitter was abolished, while MEPP amplitude and endplate resting potential remained constant. Effects of the potent cation ionophore X537A on MEPP frequency were blocked by 45 minutes of pre‐exposure to LPS. Because of its extremely lipophilic character, LPS apparently alters the physical structure of the presynaptic terminal membrane, eventually reducing resting and phasic Ca influx, and isolating the presynaptic terminal from ionophore

ISSN:0360-4012    

DOI:10.1002/jnr.490040204

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1979

数据来源: WILEY

摘要:

AbstractNeuroglial synapses have been systematically observed in histotypical cerebellar rotary tissue cultures. These axoglial contacts appear as excitatory‐like synapses in which the presynaptic element contains rounded synaptic vesicles accumulated at the presynaptic active zone. The postsynaptic structures were always the somata as well as processes of astrocytic glial cells. The axoglial contacts appear in these cultures when they are prepared from 16‐day‐old chick embryos cerebellum and cultivated during 6 days. To explain these neuroglial interrelationship it has been suggested as a working hypothesis that glial and nerve cells develop plastic capacities in order to establish synaptic contact in the in vitro condi

ISSN:0360-4012    

DOI:10.1002/jnr.490040205

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1979

数据来源: WILEY

摘要:

AbstractThe effects of polarizing currents and repetitive stimulation on the uptake of representative amino acids have been studied in peripheral nerve. Glutamic acid, lysine, pheylalanine, and GABA were chosen for study as representatives of different carrier‐mediated transport mechanisms. Depolarizing currents inhibited uptakes of glutamic acid, lysine, and GABA; maximum inhibitions were 56.1%, 20.0%, and 16.7%, respectively. Pheylalanine uptake was not inhibited by polarizing currents under any experimental conditions. Only glutamic acid uptake was inhibited by hyperpolarizing current, with a maximum inhibition of 43.9%. Stimulation had no significant effect on uptake of lysine, phenylalanine, or GABA but was found to potentiate uptake of glutamic acid by 12

ISSN:0360-4012    

DOI:10.1002/jnr.490040206

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1979

数据来源: WILEY

摘要:

AbstractUptake of 2‐deoxy‐D‐glucose (2‐DG) has been studied in synaptosomes from the Long–Evans rat. Although there are some differences, the results are generally similar to those reported for Sprague–Dawley rats. Both D‐glucose and 2‐DG are taken up by the same carrier, since D‐glucose was found to inhibit uptake of 2‐DG. Uptake is highly dependent on a source of metabolic energy, since incubation at 0°C completely eliminated uptake, while 10−3M 2, 4‐dinitrophenol (DNP) inhibited uptake by 76.5%.Uptake has also been measured as a function of both 2‐DG and sodium concentration and the data fitted to a model. Sodium is found to inhibit uptake. A model assuming noncompetitive inhibition by sodium gives best fit to the data. Thus both Kt and apparent Vm are dependent on the sodium concentration. Although these effects are small, Kt increases with [Na],

ISSN:0360-4012    

DOI:10.1002/jnr.490040207

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1979

数据来源: WILEY

摘要:

AbstractA major and several minor tricholoroacetic acid (TCA) soluble, bioassayable melanotropic peptides, as well as bioreactive and immunoreactive α‐MSH have been found in the hypothalamus, olfactory bulb and cerebral cortex of normal and hypophysectomized rats. By employing subcellular fractionation procedures it was demonstrated that α‐MSH and the major TCA soluble melanotropic peptide (MMPB) were localized in synaptosomes and were released by hypoosmotic shock. The analysis of MMPBby electrophoretic and chromatographic procedures reveals that it is not ACTH4−10, ACTH1−10, ACTH1−24, NAcACTH1−10or α‐MSH. MMPBwas found to cross‐react with an antiserum specific for the Lys‐Pro‐Val NH2sequence in α‐MSH, indicating that this C‐terminal sequence of α‐MSH may be present in its structure. MMPBwas also shown to differ electrophoretically from the two major TCA soluble melanotropic peptides found in the neurointermediate lobe of the pituitary. In view of their synaptosomal localizations MMPBand α‐MSH may play a role in synapt

ISSN:0360-4012    

DOI:10.1002/jnr.490040208

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1979

数据来源: WILEY

ISSN:0360-4012    

DOI:10.1002/jnr.490040209

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1979

数据来源: WILEY

ISSN:0360-4012    

DOI:10.1002/jnr.490040201

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1979

数据来源: WILEY