摘要:

AbstractHypoxia and ischemia produced the changes in the rat brain lipid composition. Moderate decreases in the content of phospholipids, cerebrosides, and gangliosides were observed. Three different experimental models of oxygen deficiency varied as to the degree of energy disturbances were correlated with their effect on the particular lipid classes. The decrease of cerebrosides content, but not gangliosides and phospholipids, could be attributed directly to energy disturbances and concomitant restriction of glucose supply to the hypoxic‐ischemic brai

ISSN:0360-4012    

DOI:10.1002/jnr.490070402

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

年代:1982

数据来源: WILEY

摘要:

AbstractTo study the influence of cell surface‐associated molecules on intercellular communication, C6 glioma cells were cultured both on plastic and on substrata of paraformaldehyde‐fixed B104 neuroblastoma cells. By then comparing the phenotypic expression of these “cocultured” C6 cells with cells cultured on tissue culture plastic, the influence of the cellular substratum was determined.The beta‐adrenergic‐responsive cyclic AMP‐generating system of C6 cells was compared on these various substrata. We found that fixed beds of dibutyryl cyclic AMP (dbcAMP)‐treated B104 cells uncoupled beta‐receptors from adenylate cyclase, whereas fixed beds of similarly treated C6 cells did not. However, other cellular properties were not affected by growth atop fixed dbcAMP‐treated B104 cell beds including the rate of C6 cellular proliferation and their rate of protein synthesis. The cell surface‐associated determinant on B104 cells capable of uncoupling the beta‐responsive cyclase system of C6 cells is probably a protein, as judged by its susceptibility to protease treatment.Other properties of C6 cells were also affected by the various substrata including basal and hydrocortisone‐induced levels of glycerol phosphate dehydrogenase (GPDH; an oligodendroglial marker) and the rate of RNA

ISSN:0360-4012    

DOI:10.1002/jnr.490070403

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

年代:1982

数据来源: WILEY

摘要:

AbstractLeucine aminotransferase (EC 2.6.1.6) and 2‐oxoisocaproate dehydrogenase (EC 1.2.4.3) were studied in rat cerebral cortex, cerebellum, brain stem, liver, and muscle in normal and animals starved for 48 hours. In the brain, leucine aminotransferase, valine aminotransferase, and 2‐oxoisocaproate dehydrogenase showed a significant increase in starvation only in cerebellum while there was increase in 2‐oxoisocaproate dehydrogenase in cerebral cortex only. A significantly high increase in the activity of 2‐oxoisocaproate dehydrogenase was observed in muscle in starvation. A significant decrease in the activity of leucine aminotransferase was observed in liver in starvation. The increase in the activity of 2‐oxoisocaproate dehydrogenase in muscle and a decrease in the activity of leucine aminotransferase in liver in starvation indicate that the leucine is predominantly metabolized in extra hepatic tissues particularly in muscle.As a result of intraperitoneal administration of 2 ml of leucine (5 mM), a significant increase in 2‐oxoisocaproate dehydrogenase occurred in cerebral cortex, liver, and muscle while a profound increase in the activity of glutamate dehydrogenase (EC 1.4.1.2) was observed in all the brain regions and liver under these conditions. A significant increase in the content of glutamic acid, alanine, and GABA was observed in all the three regions of the brain after the administration of leucine. A significant increase in the content of glutamine was observed only in the cerebellum and cerebral cortex after leucine administration. These results indicate that leucine in brain might contribute to the formation of glutamate, not only by transmination, but also by promoting glutamate dehydrogenase activity. Thus, there is a change in the metabolism of glutamate family of amino acids and energy depletion. These results are discussed in relation to the bra

ISSN:0360-4012    

DOI:10.1002/jnr.490070404

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

年代:1982

数据来源: WILEY

摘要:

AbstractDay‐night differences in the areas of granular endoplasmic reticulum, Golgi apparatus, dense‐core vesicles, and lysosomelike bodies were analyzed morphometrically in the pinealocytes of the chipmunk. The area of lysosomelike bodies was greater at night and lower during the daytime. In contrast, the areas of granular endoplasmic reticulum and dense‐core vesicles were greater during daytime and lower at night. Our observations suggest the existence of 24‐hour rhythms in the areas of these structures, perhaps indicative of a pineal rhythm in secretion, whether indolic or pept

ISSN:0360-4012    

DOI:10.1002/jnr.490070405

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

年代:1982

数据来源: WILEY

摘要:

AbstractNerve growth factor interacts with responsive cells by binding to cell surface membrane receptors. There are two different receptors on both embryonic sensory and sympathetic neurons, a high‐affinity (type I) receptor and a lower‐affinity (type II) receptor. Sequestration, which we have defined as bound nerve growth factor that becomes inaccessible to the external milieu with time, occurs through the type I receptor on both sensory and sympathetic neurons. We describe here a process subsequent to sequestration involving internalization and degradation of bound nerve growth factor and showing that bound nerve growth factor is not degraded under the following conditions: (1) low temperature, ie 4°C; (2) when a large excess of unlabeled nerve growth factor is added concomitantly with the labeled nerve growth factor and the temperature is raised from 4°C to 37°C; (3) when metabolic inhibitors sodium fluoride and dinitrophenol are added concomitantly with the labeled nerve growth factor and the temperature is raised from 4° to 37°C. On the other hand, conditions that allow bound nerve growth factor to be degraded are the following: (1) incubation of the sensory nerve cells at low temperature (ie, 4°C) only in the presence of labeled nerve growth factor, then raising the temperature to 37°C; (2) when sodium fluoride and dinitrophenol are added when the temperature is raised to 37°C; (3) when excess unlabeled nerve growth factor is added when the temperature is raised to 37°C.These studies are consistent with the idea that nerve growth factor has to bind to the cells in order to be degraded; however, binding is not sufficient for degradation to occur. Second, the bound nerve growth factor must be sequestered in order to be degraded. Third, the process of internalization of the bound nerve growth factor, unlike sequestration, is not an energy‐dependent process. Thus, it seems reasonable to suggest the following steps for the interaction of nerve growth factor with responsive cells: binding to a cell surface membrane receptor, followed by sequestration of the bound nerve growth factor, and finally, internalization of the sequestered nerve

ISSN:0360-4012    

DOI:10.1002/jnr.490070406

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

年代:1982

数据来源: WILEY

摘要:

AbstractA human neuronal and a human glioma line were used to study lithium (Li) transport mechanisms and kinetics of influx. We demonstrated that, unlike the human erythrocyte or clonal neuroblastoma cell SY5Y, the cloned glioma cell line A1B1had neither a ouabain or phloretin‐sensitive component of Li influx. Furthermore, glioma cells were shown to accumulate significantly more (4 fold) Li and at an apparently faster rate when compared to the neuroblastoma cell, SY5Y, over the same time period. Thus, these two clones may be better in vitro model system for the study of Li transport components native to the human central nervous system as compared to erythrocytes. This study also suggests that glial tissue may preferentially accumulate Li and in this way control the levels of extracellular Li surrounding some neuron

ISSN:0360-4012    

DOI:10.1002/jnr.490070407

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

年代:1982

数据来源: WILEY

摘要:

AbstractIsoniazid is a useful chemical convulsant in that metabolic events associated with the preseizure state can be easily examined. In the present study, net levels of glucose, glycogen, ATP, and phosphocreatine were measured using enzymatic techniques in control mice, and in those injected with isoniazid. Results from this study showed a differential effect of isoniazid on cells from the cerebral cortex and the cerebellum. In the preseizure stage, the high energy phosphates ATP and phosphocreatine were decreased in layer 1 and the pyramidal cell layer of the cerebral parietal cortex, but were unchanged in the cerebellum. At the onset of seizures, metabolites were decreased not only in cortical layers, but in the molecular layer and Purkinje cell rich layer of the cerebellum as well. The somewhat delayed response of the cerebellum emphasizes the differential nature of metabolism in various brain regions. Such a delay in cerebellar energy response to perturbation may be conducive to the seizure state. In another series of mice, either sodium valproate or clonazepam was administered prior to isoniazid, and metabolite studies repeated. Results showed that at a time when each anticonvulsant acted to eliminate overt seizure activity, the reduction in ATP and phosphocreatine was not as great as it was in seizing mice treated with isoniazid alone.

ISSN:0360-4012    

DOI:10.1002/jnr.490070408

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

年代:1982

数据来源: WILEY

摘要:

AbstractIn experiments with 11 human subjects and 12 rhesus monkeys given14C‐labeled amino acids intravenously, blood samples were drawn simultaneously from the femoral artery (A) and the superior bulb of the internal jugular vein (V). Analyses of labeled and unlabeled free amino acids indicated that both A‐V and V‐A differences resulted with each amino acid. In no case were there consistent A‐V or V‐A differences (excepting with L‐[methyl‐14C] methionine where consistent A‐V differences resulted). However, in experiments with rhesus monkeys, from 0.2% to 2.3% of the injected14C‐labeled amino acids was taken up by brains 90–120 minutes after injection. Therefor, it was suggested that, in humans and monkeys in vivo, small but significant amounts of amino acids enter the brain from blood over a period of time by a bidirectional

ISSN:0360-4012    

DOI:10.1002/jnr.490070409

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

年代:1982

数据来源: WILEY

摘要:

AbstractDifferentiation of the ventral motor neurons were followed in the developing human spinal cord from week 8 to week 26 of intrauterine life by thionin staining and the rapid Golgi method. Ventral roots were seen as translucent rootlets by week 8 and the ventral motor neurons were clearly identifiable by week 10, indicating that the ventral grey was earlier to differentiate than the dorsal grey, which showed a small, darkly stained, undifferentiated cell population. Lateral groupings of the motor neurons in the cervical and lumbar enlargements were obvious by week 10. Nissl substance and dendrites had reached an adult pattern by about week 18 of intrauterine life.

ISSN:0360-4012    

DOI:10.1002/jnr.490070410

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

年代:1982

数据来源: WILEY

摘要:

AbstractExpiratory neurons in the area of the nucleus retroambigualis were studied in anesthetized cats to determine their responsiveness to the iontophoretic application of the putative neurotransmiters, glutamate and gamma‐aminobutyric acid (GABA). Previous studies with glutamate and GABA revealed that these two substances were very effective in modulating the spontaneous activity of phasic medullary respiratory neurons. Mechanical loading of expiration, both resistive and elastic, was employed to test whether the presence of these transmitter substances altered the sensitivity of the expiratory cell to its volume related vagal input.Expiratory unit activity analysis included: spikes/burst, burst duration, and average firing rate. Addition of mechanical loads on expiration caused consistent increases in all parameters monitored. Iontophoretically applied glutamate (x̄ = 65 nA) resulted in modest increases in all parameters. When mechanical loads were applied in the presence of a sustained level of glutamate the effects were additive. The general shape of the firing profile observed with loading remained essentially unchanged. Application of GABA (x̄ = 46 nA) resulted in a significant decrease in the parameters monitored. However, as long as phasic activity remained, loads applied in the presence of GABA produced approximately the same absolute change as they did during control. Some cells exposed to high concentrations of GABA lost their phasic activity.This study suggests that either the synaptically activated receptors are not affected by glutamate or that these particular sites are not accessible via iontophoretic application. GABA depressed the activity of the cells in a graded fashion, but in modest concentrations did not interfere with the overall effectiveness of the vagally mediated in

ISSN:0360-4012    

DOI:10.1002/jnr.490070411

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

年代:1982

数据来源: WILEY