摘要:

AbstractThe labeling of total and poly(A) associated RNA from the subcellular fractions of cerebral cortex was studied after a 1‐hour3H‐uridine pulse in control and trained rats. In the control animals, the fraction of newly synthesized brain cortex RNA which is found in synaptosomes is the minimal one. However, in synaptosomes the proportion of poly(A)+RNA within newly synthesized RNA is maximal. Training of the rats does not influence total incorporation of label into RNA in the brain cortex and the distribution of newly synthesized RNA within the subcellular fractions. The proportions of poly(A)+RNA within total labeled RNA in the various fractions are also unaffec

ISSN:0360-4012    

DOI:10.1002/jnr.490080402

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

年代:1982

数据来源: WILEY

摘要:

AbstractBenzodiazepine receptor binding and the concentration of free tissue GABA, glutamate, glutamine, aspartate, and 13 other amino acids were estimated in specimens of cerebral cortex and cerebellum taken from normal foetuses and from perinatal and postnatal infants and adults postmortem.Compared with the ontogenetic increase, previously reported, in [3H]muscimol binding, that of [3H]flunitrazepam binding developed more rapidly in the cerebellum and less rapidly in the cerebral cortex. The concentration of GABA in both brain parts increased with age more rapidly than did that of glutamate decarboxylase activity.The overall pattern of developmental changes in the amino acid concentrations in the human brain showed many similarities with those reported in the brains of experimental animals. The concentration of the amino acids associated with the tricarboxylic acid cycle increased with age. Although the general downward trend in the levels of essential amino acids (with the exception of Met) was also evident in the human cerebral cortex, this was not the case in the cerebellum where the concentrations of most amino acids were relatively low in the foetus whereas the concentrations exceeded the cerebral cortical levels in the adult.

ISSN:0360-4012    

DOI:10.1002/jnr.490080403

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

年代:1982

数据来源: WILEY

摘要:

AbstractThe effect of thyroxine (T4) was studied on the transmembrane resting potential (Em) of rat skeletal muscle cells in culture. In agreement with previous studies, we found the Em of developing muscle cells to increase with age from Day 3 to Day 7 or 8, at which time a plateau is reached. The values of Em we obtained (−65 to −75 mV) were 15–20 mV higher than those (−50 to −55 mV) reported by others. Treatment of mature myotubes with T4resulted in a significant increase in resting Em. There was only a slight difference between T4‐treated and control cells with regard to the relation between extracellular K+concentration and resting Em. Within 20–30 min of exposure to ouabain (10−4–10−3M) resting Em of both T4‐treated and control cells had fallen to about the same value. This effect was reversible. Thus, T4stimulates the activity of an electrogenic Na/K‐ATPase in the membrane of culture

ISSN:0360-4012    

DOI:10.1002/jnr.490080404

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

年代:1982

数据来源: WILEY

摘要:

AbstractFiltration and microcentrifugation procedures for the separation of bound and free ligand are compared for the assay of GABA receptors. The3H‐GABA and3H‐muscimol are employed as ligands in saturation analyses of SPM and JC preparations. A direct comparison of the two methods, applied to two membrane preparations and two ligands, reveals that nonspecific binding is consistently higher with the microcentrifugation procedure. Analysis of the binding data yields essentially the same constants in either case; however, the filtration assay provides a better estimate in all ca

ISSN:0360-4012    

DOI:10.1002/jnr.490080405

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

年代:1982

数据来源: WILEY

摘要:

AbstractField and extracellular unitary potentials were recorded in the ventromedial nucleus of the hypothalamus (VMH) of urethane‐anesthetized rabbits after stimulation of the fimbria and stria terminalis.Stimulation of the lateral portion of the fimbria, which carries fibers from the ventral subiculum of the hippocampal formation, evoked a two‐component response. An early excitatory response, with an average latency of 10 msec, predominated along the lateral margins of the VMH. A later inhibitory potential with an average latency of 15 msec was seen predominantly within the central portions of the VMH. Stimulation of the dorsal component of the stria terminalis produced two similar response patterns: an early excitatory response with an average latency of 16 msec, followed by an inhibitory potential with an average latency of 25 msec. The topographical distribution of these two components of the response was nearly identical to that produced by lateral fimbria stimulation. In contrast, stimulation of the ventral component of the stria terminalis evoked a simple excitatory response with an average latency of 10 msec which was maximal within the core of the VMH.Extracellular unitary recodings showed that the early negativity associated with stimulation of each of these three pathways reflects a monosynaptic excitation of VMH cells and that there was convergence of the three excitatory inputs at the single cell le

ISSN:0360-4012    

DOI:10.1002/jnr.490080406

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

年代:1982

数据来源: WILEY

摘要:

AbstractHigh‐affinity uptake, potassium‐stimulated release and receptor binding of γ‐aminobutyric acid (GABA) and taurine were studied in retinas of rats treated with monosodium glutamate (MSG) or iodoacetate‐malate (IAM). Such treatments produce a selective damage of the inner retinal layers (MSG) or of the photoreceptor layer (IAM).MSG treatment decreased GABA uptake by more than 60%. Also, the potassium‐stimulated release of this amino acid was markedly diminished (90%) in retinas lesioned by MSG. MSG treatment decreased3H‐GABA binding by 45%. Uptake, release or binding of GABA were unaffected by IAM‐treatment.Taurine uptake was reduced by a similar degree by both MSG and IAM treatment, 57% and 38% respectively. Potassium‐stimulated release of taurine was unchanged by MSG and 50% reduced by IAM. Both treatments reduced the spontaneous release of endogenous taurine. Binding of taurine to receptors in retinal membranes was practically unaffected by any of the treatments utilized.These results are consistent with a neurotransmitter action of GABA at the inner retinal layers, while they do not support a major role for taurine as a synaptic trans

ISSN:0360-4012    

DOI:10.1002/jnr.490080407

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

年代:1982

数据来源: WILEY

摘要:

AbstractThe effects of cortical lesions and intrastriatal kainic acid injections on various striatal enzyme activities were investigated. Ornithine aminotransferase decreased concomitantly with glutamate uptake in decorticated and chronic kainic acid‐treated rats. It was also decreased in acute kainic acid‐lesioned striatum where glutamate uptake was unaffected. Aspartate aminotransferase, however, decreased only after acute kainic acid treatment. Results for glutamate uptake, glutamate decarboxylase, and choline acetyltransferase were in agreement with previous findings. These results suggest that ornithine may act as a precursor for glutamate in nerve terminals, although the nonspecific localization does not allow ornithine aminotransferase to be a convenient biochemical marker. The decrease in aspartate aminotransferase is thought to be due to be widespread cell degeneration after acute kainic acid. Aspartate aminotransferase activities were also found to be reduced in the frontal cortex, caudate nucleus and putamen of Huntington's disease bra

ISSN:0360-4012    

DOI:10.1002/jnr.490080408

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

年代:1982

数据来源: WILEY

摘要:

AbstractNorepinephrine and dopamine were examined in 19 discrete brain areas from the telencephalon, diencephalon, and mesencephalon of nutritionally rehabilitated adult rats following postnatal undernutrition from birth through 21 days of age. Following rehabilitation, catecholamine levels were not significantly different from control values in any of the areas examined. Catecholamine concentrations in young, undernourished rats are generally elevated (either from stress or from nutritional insufficiency). Data presented here show that whichever case is true, the early effect of undernourishment is transient and that normal values are restored by nutritional rehabilitation.

ISSN:0360-4012    

DOI:10.1002/jnr.490080409

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

年代:1982

数据来源: WILEY

摘要:

AbstractThe activity of inspiratory neurons in the nucleus tractus solitarius (NTS) and of expiratory neurons in the nucleus retroambigualis (NRA) was recorded during the iontophoresis of L‐glutamate, bicuculline, and strychnine in chloralose‐urethane‐anesthetized cat. Bicuculline methoxide caused increased activity of NTS and NRA neurons during their active or burst phases. Neither bicuculline nor strychnine caused increased activity during the silent phases of NTS or NRA neurons. When neurons were driven to fire during their silent phase by L‐glutamate, the application of bicuculline methoxide caused a diminution of the evoked activity. It is concluded that both inspiratory and expiratory neurons receive inhibitory inputs during both their active and silent phases. Gamma‐aminobutyric acid appears to be gating both the excitatory and inhibitory information to NTS and NRA neurons. Strychnine was generally ineffective in changing the firing patterns of inspiratory and expiratory neurons suggesting a limited role of glycine, taurine, and L‐alanine in the respirat

ISSN:0360-4012    

DOI:10.1002/jnr.490080410

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

年代:1982

数据来源: WILEY

摘要:

AbstractWe investigated alterations in opiate‐binding sites in the upper dorsal horn after transection of the related peripheral sensory nerve in rats. The binding of (3H)diprenorphine was measured autoradiographically. The findings indicated a shift of the binding sites, rather than a degenerating disappearance, with a decrease in nerve fibers but an increase in nerve cells. This may be due to latent opiate‐binding sites becoming manif

ISSN:0360-4012    

DOI:10.1002/jnr.490080411

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

年代:1982

数据来源: WILEY