摘要:

AbstractCentral nervous system neurons, cultured as monolayers at low density, need exogenous pyruvate for their survival. The pyruvate concentrations required by embryonic day 8 (E8) chick forebrain neurons are reduced substantially by other low molecular weight agents present in Dulbecco's modified Eagle's medium (DMEM) and in astroglia‐conditioned Eagle's basal medium (EBM). To examine the nature of these pyruvate‐sparing molecules, E8 chick forebrain neurons were cultured in EBM containing a concentration of pyruvate too low to support neuronal survival, unless sparing agents were supplied. This stragegy permitted the identification of the pyruvate‐sparing DMEM constituents, omission of which had led to neuronal loss. Pyruvate sparing required a mixture of (i) serine, (ii) pyrioxal (or riboflavin and biotin), and (iii) six essential amino acids: arginine, cystine, leucine, isoleucine, tyrosine, and tryptophan (each replaceable by corresponding amino acids, except tryptophan). All pyruvate‐sparing contributors were optimally needed at or near their DMEM concent

ISSN:0360-4012    

DOI:10.1002/jnr.490140302

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe spinal cords of young and adult normal and dysmyelinating mutant (shiverer) mice were immunostained with anticarbonic anhydrase to investigate (1) the distribution of oligodendroglial populations into the gray‐ and white‐matter regions in the developing normal and mutant animals; (2) the morphology of oligodendrocytes and their processes at the light microscopic level in gray matter and white matter; and (3) the apparent gliosis in the gray matter, as well as the white matter, of the mutants. Immunocytochemistry and enzyme assays revealed consistent increases in carbonic antigenicity and specific activity in controls and mutants between the ages of ˜ 15 days and ˜ 60 days. As shown previously in adult animals, oligodendroglia in larger than normal proportions were situated at the periphery of the “white‐matter” columns, as compared to gray matter, in the shiverers, with, however, significant numbers of oligodendroglia also occurring in gray matter. In normal white matter, at all ages, the oligodendroglia were heterogeneous with respect to shapes, configuration of processes, and intensity of carbonic anhydrase immunostaining. In the shiverer “white matter” the oligodendrocytes were smaller than normal, and their shapes and arrangement were relatively irregular. In the normal gray matter short oligodendroglial processes appeared to be associated with neuronal perikarya, and those processes were more pronounced at ˜ 90 days than at ˜ 20 days of age. Background staining in normal gray matter suggested that oligodendroglial processes were, in addition, tightly wound around many axons. In shiverer gray matter the oligodendrocytes were smaller, and their processes appeared to be wrapped more loosely around smaller numbers of conspicuous axons and to be associated less frequently with neuronal perikarya. This finding suggests that the deficiency in the myelin basic protein in the mutant may affect interaction betwen oligodendrocytes and neurons in the gray matter as well as in the white matter. The astrocytic “marker,” glial fibrillary acidic protein, was detected in gray and white matter of shiverers as young as 16 days, and the differences from carbonic anhydrase localization supported the conclusion that the processes enwrapping axons in the shiverer mouse CNS are derived from oligodendro

ISSN:0360-4012    

DOI:10.1002/jnr.490140303

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

年代:1985

数据来源: WILEY

摘要:

AbstractWe report here that high‐affinity uptake mechanisms for two or three putative neurotransmitter molecules coexist in many of the neurons present in glia‐free, purified neuronal monlayers from chick embryo retina. Replicate cultures were incubated with the tritiated forms of the amino acids gamma‐aminobutyric acid (GABA), taurine (TAU) and aspartate (ASP) either individually or in binary or in binary or tertiary combinations. Incubation conditions were those typically used to analyze high‐affinity uptake mechanisms. At the end of the incubation period the cultures were either lysed in water for measurement of intracellular radioactivity by liquid scintillation counting, or fixed in glutaraldehyde and prepared for autoradiography. Our results indicate that there is coexistence of uptake mechanisms for putative neurotransmitters in retinal cells. Biochemical measurements showed that, at the concentrations used in these experiments, two or more radioactive amino acids could be taken up simultaneously by the cultured populations without extensive inhibition. Moreover, the percentage of cells that appeared autoradiographically labeled in cultures exposed to two or more radioactive amino acids was less than the sum of the percentages of labeled cells when each amino acid was applied individually. Numerical analysis of the autoradiographs was carried out to determine the percentage of cells that coul take up only one, only two, or the three putative amino acid neurotransmitters under investigation. This analysis showed that approximately 20% of the neurons have only the mechanism for TAU, whereas very few if any neurons have high‐affinity uptake mechanisms for GABA alone or ASP alone. Our experiments have identified populations of cells that take up GABA and TAU (but not ASP) or ASP and TAU (but not GABA). Interestingly, we have not seen any neurons that can take up ASP and GABA and cannot take up TAU, although as many as 50% of the neurons can take up ASP, GABA, and TAU simultaneously. By showing simultaneous uptake of different putative neurotransmitters within individual neurons, our results emphasize the concept that the presence in a given neuron of a high‐affinity mechanism for a particular molecule is not a sufficient criterion to assign a neurotransmitter function to that molecule in

ISSN:0360-4012    

DOI:10.1002/jnr.490140304

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe factor(s) present in extracts prepared from the brains of newborn A/J or C57B1/6 mice, with inhibits S20Y neuroblastoma cell growth in vitro, was partially characterized. Twice as much ingibitory activity was extracted per gram wet weight of brain than torso, and inhibitor recovery was greatest in extracts prepared from brains of mice 1 week or less in age. The inhibitory factor(s) was water‐soluble and was stable to heating at 100°C, to freezing, and to lyophilization. It was susceptible to the action of pronase. The factor(s) behaved like a molecule of molecular weight ˜ 700 upon passage through ultrafiltration membranes. Growth of rat hepatoma (H4), murine melanoma (B16), and transformed murine fibroblasts (WT19 and B6‐HCMV) was not significantly inhibited by brain extract. Growth of rat glioma cells (C6) was significantly reduced but to a lesser degree than that of murine neuroblastoma cells (S20Y and N 115) and glioma cells (G26‐20). These results suggest that the inhibitor expresses a cell spec

ISSN:0360-4012    

DOI:10.1002/jnr.490140305

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

年代:1985

数据来源: WILEY

摘要:

AbstractA single intraocular injection of 1 or 3 nmol kainic acid (KA) into the right eye of rats aged 5 days postnatal (5 dpn) significantly reduced the incorporation of3H‐proline into retinal proteins and suppressed the amount of3H‐proline‐labeled materials fast axonally transported in the optic nerve for at least 2 weeks thereafter. Intraocular KA injection within this dose range had no adverse effect on the optic axon population compared to normal nerves determined at 21 dpn; however, doses above 3 nmol (i.e., 6 nmol) caused significant axonal degeneration. Although partially recovered by 21 dpn this effect of KA on protein synthesis and axonal transport suggests that, as in the adult, retinal ganglion cells are also KA‐sensitive during postnatal deve

ISSN:0360-4012    

DOI:10.1002/jnr.490140306

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe brain and plasma levels of immunoactive delta sleep‐inducing peptide (DSIP) as well as the permeability of the blood‐brain barrier (BBB) to radioiodinated N‐Tyr‐DSIP (125I‐DSIP) were measured at 0400, 0800, 1200, 1600, 2000, and 2400 hr in rats in a normal 12‐hr‐light/12‐hr‐dark cycle and at 0800 in rats in constant light or constant dark. Both brain and blood levels of immunoactivity showed statistically significant dirunal changes, whereas the measurement of BBB permeability varied in a regular fashion over time without the changes reaching statistical significance. Immunoactive levels of DSIP in both plasma and the brain were higher and permeability of the BBB to125I‐DSIP increased in both the constant light and especially the constant dark groups incomparison with the cycled 0800 group. Diurnal variations continued to occur in the blood levels of immunoactive DSIP in the constant dark animals. Studies with radioiodinated serum albumin (RISA) showed that these findings did not result from a change in brain hemodynamics. Immunoactive levels of DSIP in the plasma correlated with brain immunoactive levels and with BBB permeability to125I‐DSIP. The increase in penetration of125I‐DSIP into the brain that occurred with changes in the lighting cycle appeared to be magnified by pre‐treatment with aluminum. The results show interrelationships among various aspects of the neuroendocrine axis for DSIP and their modulation

ISSN:0360-4012    

DOI:10.1002/jnr.490140307

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe somatosensory barrels in layer IV of rat cerebral cortex were studied on uniformly oriented, serial, tangential sections by a combination of light microscope and ultrastructural techniques. Section orientation between sections was maintained by blood vessel patterns. The principal elements of both anterior and posterior barrels were quantified and analyzed in relation to proportional content and nonrandom spatial arrangement over depth in layer IV. Elements studied in this manner included neurons, myelinated axons, apical dendrites, synapses, glial cells, and blood vessels. In general, constituents were found to be arranged in a highly ordered fashion similar to other discretely organized sensory cortical areas. Myelinated axons outlined the basic structure of the barrels with the osmium stainig employed. Neurons appeared organized in small clusters. In addition apical dendrites, synapses, and blood vessels also exhibited nonrandom distribution complementary to the organization of axons and neurons. Anterior and posterior barrels differed slightly in their organization of elements.

ISSN:0360-4012    

DOI:10.1002/jnr.490140308

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

年代:1985

数据来源: WILEY

摘要:

AbstractFast Fourier Transform analyses were performed on finger tremor movements at 0.2‐Hz intervals from 0.4 to 40 Hz in 10 human subjects, under a flickering light condition of 4–15 Hz and an unstimulated control condition. Under the control condition, the power spectrum showed an essentially normal curve distribution, except for an early frequency component in the histogram. In contrast, when the flickering light stimulus was presented, the power of specific frequency components at 8–1 Hz was strongly enhanced. This effect was induced exclusively at a frequency of 8, 9, or 11 Hz of flickering light, and this flickering frequency producing the enhancement effect differed from subject to subject. There existed a significant correlation between the frequencies of flicker and tremor at the tuned frequency. These findings demonstrate that a specific frequency of flickering light can intensify a specific frequency of physiological finger tremor, and that different individuals exhibit different optimal “tuning” fr

ISSN:0360-4012    

DOI:10.1002/jnr.490140309

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

年代:1985

数据来源: WILEY

ISSN:0360-4012    

DOI:10.1002/jnr.490140310

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

年代:1985

数据来源: WILEY

ISSN:0360-4012    

DOI:10.1002/jnr.490140311

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

年代:1985

数据来源: WILEY