摘要:

AbstractThe influence of sodium ions on GABA uptake into astrocytes in primary cultures has been investigated performing kinetic analysis of GABA uptake at different sodium concentrations in the range 16 to 151 mM. These investigations reveal that sodium affects both the Kmand the Vmaxof the saturable component of the astroglial GABA uptake. Uptake rates as a function of the sodium concentration at high GABA concentrations (≥ 50 μM) were clearly sigmoid whereas at lower GABA concentrations this sigmoid shape was not obvious. Accordingly, Hill plots of the sodium dependency at high GABA concentrations exhibited straight lines with slopes of 2.0 to 2.5, suggesting that the coupling ratio between sodium and GABA is at least two. Corresponding Hill plots at lower GABA concentrations exhibited slopes of 1.6 to 1.8. Moreover, plots of 1/v versus 1/Na2gave better fits to straight lines than plots of 1/v versus 1/Na which were curvilinear upward. Again, this curvilinearity was more pronounced at high GABA concentrations than at low GABA concentrations. From these results it is concluded that GABA uptake into astrocytes in primary cultures requires the binding of at least two sodium ions per GABA molecule transport

ISSN:0360-4012    

DOI:10.1002/jnr.490050602

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

年代:1980

数据来源: WILEY

摘要:

AbstractA simple method is described for simultaneously double labeling single neurons with fluorescent retrograde axonal tracers and immunofluorescence using an antibody to serotonin. Caudate‐putamen injection of orange fluorescent propidium iodide, in particular, proved effective in retrogradely labeling dorsal raphe cell bodies. These same perikarya could be stained green with the indirect immunofluorescent method, using green fluorescent fluorescein isothiocynate (FITC) as the second antibod

ISSN:0360-4012    

DOI:10.1002/jnr.490050603

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

年代:1980

数据来源: WILEY

摘要:

AbstractThe cerebral uptake of subcutaneously injected [3H] 2‐deoxyglucose (2DG) was used to determine regional changes of cerebral glucose uptake associated with peptide‐induced behaviors in mice. Evidence is presented that the use of [3H] 2DG (s.c.) gives results qualitatively similar to those obtained using intravenous [14C] 2DG. Lysine vasopressin, 1 μg intracerebroventricularly (i.c.v.), induced the characteristic hyperactivity previously described, and significantly decreased [3H] 2DG uptake in frontal cortex. ACTH1−24(1 μg, i.c.v.) induced excessive grooming and concomitant decreases in [3H] 2DG uptake in olfactory bulb, pyriform cortex, and amygdala, and an increase in cerebellum. These results are only partly consistent with previous results on the cerebral sites of action of ACTH and vasopressin. These patterns of 2DG uptake are distinct from those observed following footshock, indicating that the peptide hormones mediate the effects of footshock on [3H] 2DG uptake only partially if

ISSN:0360-4012    

DOI:10.1002/jnr.490050604

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

年代:1980

数据来源: WILEY

摘要:

AbstractRespiration was measured polarographically in astrocytes from dissociated neonatal rat cerebra grown in primary culture. Cells grown in a modified Eagle's minimal essential medium containing 20% fetal calf serum for 14 to 21 days respired at a rate of 34.23 n at. equiv 0 mg protein−1min−1. Cells which were grown in this medium for 14 days and then grown in serum‐free medium containing 0.25 mM dibutyrylcyclic‐AMP (dbcAMP) for three to six days, had respiratory rates 20% higher than in cells from untreated control cultures (P = 0.005). Maximal inhibition by oligomycin required 200 p mole per mg protein for dbcAMP‐treated cells and 80 pmole per mg protein for untreated cells. Oligomycin inhibited the respiration of both dbcAMP‐treated and untreated cells by about 70%. At a concentration of 175 nmole per mg protein, 2,4‐dinitrophenol (DNP) produced a maximal stimulation of respiration, which was 191% of the resting rate in dbc AMP‐treated cells and 218% of the resting rate in untreated cells. The maximal DNP‐stimulated respiratory rates were the same in dbcAMP‐treated

ISSN:0360-4012    

DOI:10.1002/jnr.490050605

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

年代:1980

数据来源: WILEY

摘要:

AbstractThe in vitro uptake of [35S] cysteine was studied in crude synaptosomal preparation of the cerebral cortex of rat. The accumulation of cysteine was found to be temperature‐ and time‐dependent. It was linear at least for four minutes at 37 C with characteristics of saturable kinetics. Uptake of cysteine was Na+‐ and K+‐dependent. Increasing the Na+ion concentration increased the accumulation of cysteine in synaptosomal preparations; unlike the Na+ion, an increase in the K+ion, an increase in the K+ion inhibited cysteine uptake. Cysteine was accumulated against concentration gradients by a saturable mechanism. Double reciprocal plot of the cysteine uptake suggests two types of affinity systems, with Kmvalues for the high‐affinity uptake of about 12.2 μM and for the low‐affinity uptake of about 4 mM. The high‐affinity uptake was also significantly inhibited by ouabain, a potent inhibitor of the Na+‐K+‐dependent ATPase, and other metabolic inhibitors. The results of the effects of cysteine analogues on uptake also suggested that it is a substrate‐specific high‐affinity upta

ISSN:0360-4012    

DOI:10.1002/jnr.490050606

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

年代:1980

数据来源: WILEY

摘要:

AbstractThe time course of incorporation of radiolabelled precursor into RNA associated with rat brain free polyribosomes, rough membranes, and smooth membranes was measured following a single intracranial injection of [3H] orotic acid. Polyadenylated RNAs were separated from nonpolyadenylated RNAs by affinity chromatography on oligo (dT)‐cellulose columns. Poly(A)‐RNA associated with each of the microsomal fractions became more rapidly labelled than did the nonpoly(A)‐RNA of the same fractions. While the labelling profiles of the nonpoly(A)‐RNA isolated from the polyribosomes and rough membranes are similar from one fraction to another, the specific radioactivity of the poly(A)‐RNA isolated from free polyribosomes increased much more drastically than that of the poly(A)‐RNA associated with rough membranes. The labelling profiles of RNA species isolated from smooth membranes were very different in this respect from the two ribosomal fractions. There was a lag of more than four hours before significant label appeared in the RNA associated with the smooth membrane fraction. These studies demonstrate that the different populations of brain microsomal RNA are labelled at different rates, perhaps reflecting differences in the turnover of these RNAs and differences in the

ISSN:0360-4012    

DOI:10.1002/jnr.490050607

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

年代:1980

数据来源: WILEY

摘要:

AbstractBiochemical studies on the hippocampus of acutely prepared rabbits revealed more than two fold increases in cyclic GMP levels following tetanic potentiation of the pathway from the medial septal region to CA1pyramidal cells. Diazepam, administered intravenously, prevented the elevation in cyclic GMP levels in this region and also attenuated the post‐tetanic potentiation seen following the presentation of trains at frequencies within theta rhythm. The results imply a modulatory role for cyclic nucleotides in the enhancement of pyramidal cell excitability and suggest that the biochemical mechanism for the psychoactive benzodiazepines may well include the suppression of cyclic GMP level

ISSN:0360-4012    

DOI:10.1002/jnr.490050608

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

年代:1980

数据来源: WILEY

摘要:

AbstractIn the abdominal ganglion of Aplysia kurodai, three neurons were identified that responded with inhibition of long duration (ILD) to a single stimulation of the siphon nerve and to bath and iontophoretic application of dopamine. The ILD is a long‐lasting (15–60 sec) hyperpolarizing potential, typically associated with a conductance increase but with a reversal potential more negative than the potassium equilibrium potential. Exchange of half the external chloride with acetate induced no change in the ILD. The ILD was reduced in amplitude in the presence of 0.1 normal K+in the external medium and enhanced in two times normal K+solution. The ILD amplitude, but not conductance, was progressively impaired by cooling and by the metabolic inhibitors ouabain and strophanthidin. These results suggest that the ILD is composed of an increase in K+conductance and activity of the electrogenic Na‐pump. Theophylline potentiated the ILD, especially its duration. Furthermore, bath application of dibutyryl cAMP augmented the amplitude of the synaptically elicited ILD and the dopamine responses by 30% over controls without any effect on the change in membrane conductance. Intracellularly injected cAMP also increased the ILD, but 5′‐AMP showed no such effect. These data suggest that dopamine acts on the ILD neurons by increasing K+conductance and the activity of the electrogenic Na‐pump and that cAMP might selectively stimulate the pump component

ISSN:0360-4012    

DOI:10.1002/jnr.490050609

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

年代:1980

数据来源: WILEY

摘要:

AbstractThe distribution of cysteinesulfinic acid decarboxylase (CSAD) activity has been studied for some time on the assumption that this activity was a marker for taurine‐containing structures in the CNS. We have found that various in vivo and in vitro treatments of CNS tissues result in parallel changes in the activities of CSAD and glutamic acid decarboxylase (GAD). This suggests that the assay for CSAD is in fact measuring predominantly GAD activity. This hypothesis is tested by lesion, regional distribution, kinetic, inhibitor, and stability studie

ISSN:0360-4012    

DOI:10.1002/jnr.490050610

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

年代:1980

数据来源: WILEY

摘要:

AbstractThe axoplasmic transport of proteins in spinal motor neurons is altered by pargyline, a drug that causes increased release of monoamines. Two new peaks of transported protein were detected in the sciatic nerves of rats treated with pargyline (75 mg/kg/day ip for three days). These peaks moved with velocities of 595 mm/day (peak I) and 1,230 mm/day (peak II). The bulk of labeled protein was still transported at the control rate of 362 mm/day. Electrophoresis of transported polypeptides labeled with [35S] methionine showed that peak I material was qualitatively similar to material transported at the normal rate in controls, but peak II material contained fewer labeled polypeptides. Both peak I and peak II differed from controls in the relative intensity of labeling of various polypeptides. Fast axoplasmic transport in sensory neurons was unaffected by pargyline. Intraspinal injection of pargyline (50 μg/day for three days) caused changes in axoplasmic transport similar to those induced by intraperitoneal pargyline. These results show that transport of certain proteins along a peripheral nerve can be accelerated by a mechanism initiated in the region of the nerve cell bodies

ISSN:0360-4012    

DOI:10.1002/jnr.490050611

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

年代:1980

数据来源: WILEY