bluuebunny/crossref_metadata_2025 huggingface dataset:
ACTIONS OF NEUROHUMORAL AGENTS AND CEREBRAL METABOLITES ON OUTPUT OF ADENINE DERIVATIVES FROM SUPERFUSED TISSUES OF THE BRAIN
Authors: Pull I. , McIlwain H.
Published: October 2006

—Adenine nucleotides of guinea‐pig neocortical tissues were labelled by prior incubation with [14C]adenine and excess of adenine was then removed by superfusion with precursor‐free media. During continued superfusion labelled adenine derivatives were released at a stable rate of about 0·05 per cent of the tissue 14C/min and this rate was increased about five‐fold by electrical stimulation. Various compounds, including some known to increase the cyclic AMP content of cerebral tissues, were examined for action on the release of [14C]adenine derivatives from the tissue and also on the rates of lactate production by the tissue, both before and during electrical excitation. The tissue content of adenine nucleotides following exposure of the tissue to these compounds was also determined.

Noradrenaline, γ‐aminobutyrate and acetylcholine together with carbamoylcholine at the concentrations examined were without effect on the release of 14C compounds from the tissue. Also, noradrenaline and γ‐aminobutyrate caused no alteration in lactate production but brought about some decrease in the adenylate energy charge of the tissue. Histamine, 100 μm, brought about a small but consistent increase (35 per cent) both in release of 14C‐compounds and lactate output, while reducing the adenylate energy charge of the tissues. l‐Glutamate at 5 mm decreased the tissue adenylate energy charge to a greater extent than did histamine; it increased the release of 14C‐compounds seven to eight‐fold and similarly increased the tissues' rates of lactate production. Lower concentrations of glutamate had smaller effects. In those cerebral tissues whose cyclic AMP content is increased by l‐glutamate, the increase is probably brought about by intermediation of released adenosine.
THE SUBCELLULAR DISTRIBUTION OF β‐PHENYLETHYLAMINE, p‐TYRAMINE AND TRYPTAMINE IN RAT BRAIN
Authors: Boulton A. A. , Baker G. B.
Published: October 2006

—The quantitative subcellular distribution of β‐phenylethylamine, p‐tyramine and tryptamine in rat brain was investigated using the mass spectrometric integrated ion current technique. More of the total cellular tryptamine was found to be associated with paniculate fractions than was the case for phenyiethylamine and p‐tyramine but a significant amount of this tryptamine was found to be labile. Analysis of the particulate fractions indicated that each of the amines was localized predominantly in the crude P2 pellet and that the bulk of this was associated with the synaptosomal (P2B) fraction. Inhibition of monoamine oxidase systems with pargyline caused an increase in the level of all three amines in all fractions, but the increase was greater in the supernatant than in the combined particulate fractions. This treatment produced changes in the distribution of β‐phenylethylamine and p‐tyramine between the various particulate subcellular fractions but did not markedly alter the distribution of tryptamine between the same fractions.
ACETYLCHOLINESTERASE TURNOVER IN BRAIN, CEREBROSPINAL FLUID AND PLASMA
Authors: Yaksh T. L. , Filbert M. G. , Harris L. W. , Yamamura H. I.
Published: October 2006

—By assay of acetylcholine hydrolysis to measure total cholinesterase activity and acetyl‐β‐methylcholine hydrolysis to measure acetylcholinesterase (E.C 3.1.1.7) activity, patterns of regeneration of enzyme activity were measured in seven areas of brain, cerebrospinal fluid and plasma of cats after administration of an irreversible inhibitor. Halftimes of recovery of total cholinesterase in the brain tissues ranged from 0·9 to 3·8 days (av = 2·5 days) and acetylcholinesterase recovery halftimes ranged from 1·2 to 5·3 days (av = 3·6 days).

Regeneration of total cholinesterase was also followed in subcellular fractions of guinea‐pig and rat brains after similar inhibition. In both species, the fastest recovery occurred in the soluble fraction with halftimes of 1·8 and 1·6 days, while the synaptosomal fractions exhibited the slowest recoveries with halftimes of 8·3 and 4·1 days. Regeneration of activity in plasma and CSF most nearly resembled that of the soluble brain fraction.
COPPER DEFICIENCY IN THE DEVELOPING RAT BRAIN: EVIDENCE FOR ABNORMAL MITOCHONDRIA1
Authors: Prohaska J. R. , Wells W. W.
Published: October 2006

Abstract— Copper deficiency was produced in developing rats by feeding a low copper diet to rats during gestation and lactation and providing the offspring the same diet. The progeny developed similar to those of an earlier model based on preconception depletion followed by marginal supplementation during gestation. Copper levels were greatly reduced in the brain, iron levels were slightly depressed, and no differences in zinc content were found. Electron microscopic examination of brain tissue revealed the presence of enlarge mitochondria from copper‐deficient animals. Isolated mitochondria from copper‐deficient rats showed a 30% reduction in the rate of both succinate and glutamate oxidation, and for glutamate, the respiratory control ratio (RCR) was decreased by 60%. Difference spectra displayed a four‐fold reduction in cytochrome a+a3 and slight increases in cytochrome b, c1 and c. Enzyme analysis of isolated mitochondria revealed a five‐fold decrease in cytochrome oxidase, slight increases in succinic dehydrogenase and fumarase, and small decreases in hexokinase and monoamine oxidase. No difference in peroxidation of brain lipids was evident. Determination of metabolites from fast frozen tissue suggested that the copper‐deficient brain was in a more reduced state based on a doubling of both the lactate/pyruvate and α‐glycerol‐P/dihydroxyacetone‐P ratios. Creatine‐P, ATP, and ADP levels were not different.
PUTATIVE TRANSMITTERS IN DENERVATED OLFACTORY CORTEX
Authors: Harvey J. A. , Scholfield C. N. , Graham L. T. , Aprison M. H.
Published: October 2006

Abstract—

Olfactory bulb removal and the consequent degeneration of the lateral olfactory tract led to a selective change in putative synaptic transmitters of the denervated olfactory cortex of guinea‐pigs. Nine days after bulbectomy there was a significant decrease in content of aspartate (31%) and glutamate (20%) in olfactory cortex but no change in neocortex. The content of GABA, alanine and ACh in olfactory cortex was unchanged (± 3 per cent of control). The content of 5‐HT, dopamine, NE and glycine was increased by 10‐18 per cent. The decrease in aspartate and glutamate content of the olfactory cortex after bulbectomy suggests that these two amino acids have a high concentration in fibres of the lateral olfactory tract. This tissue may prove to be useful in determining the possible role of these acidic amino acids in neuronal function.
EFFECT OF DIETARY PROTEIN AND CALORIE DEFICIENCY ON TRYPTOPHAN LEVELS IN THE DEVELOPING RAT BRAIN
Authors: Kalyanasundaram S.
Published: October 2006

Abstract—

The pattern of development of brain tryptophan in the rat was studied in the progeny of mothers fed a 7.5%; protein diet ad lib., a 20% protein diet ad lib. and those fed a 20%; protein diet pair‐fed with mothers who received the 7.5% protein. The pattern of development was similar in all three groups. Starting with a high brain tryptophan content at birth, all animals showed a progressive reduction during the next 3 weeks. However, tryptophan levels at birth were several fold higher in the brains of pups born to mothers receiving either the low protein diet fed ad lib. or those born to mothers who received the 20% protein diet in restricted amounts. From the 14th day after birth, tryptophan concentration of brain in undernourished pups was significantly lower until the 35th day. The implications of this finding are discussed.
EFFECT OF COPPER STATUS ON BRAIN NEUROTRANSMITTER METABOLISM IN THE LAMB
Authors: O'Dell B. L. , Smith R. M. , King R. A.
Published: October 2006

Abstract— Ataxic and non‐ataxic lambs reared under field conditions which gave rise to low copper status were treated with copper intravenously. Untreated ataxic animals served as controls. The neurotransmitter amines, dopamine, norepinephrine and serotonin, were determined in the anterior and posterior regions of the brain stem. Dopamine levels in the anterior region, including the corpus striatum, were significantly lower in the untreated animals than in those treated with copper. Norepinephrine levels were also lower but serotonin concentrations were not different. Plasma amine oxidase activity was markedly higher in the copper treated animals but monoamine oxidase activity in brain stem homogenates was not significantly affected. The monoamine oxidase activity in cortical and cerebellar homogenates was significantly lower in the treated animals than in the untreated animals.
ENZYMIC MODIFICATIONS IN A CULTIVATED NEUROBLASTOMA CLONE AFTER BROMODEOXYURIDINE TREATMENT
Authors: Ciesielski‐Treska J. , Tholey G. , Wurtz B. , Mandel P.
Published: October 2006

Abstract— A neuroblastoma adrenergic clone M1, which multiplies rapidly in vitro, can be induced to differentiate by addition of bromodeoxyuridine to the proliferating cells. In parallel to higher oxygen uptake, a progressive decrease of the activities of aldolase and lactate dehydrogenase is observed in BrdU treated cells. Other enzymic activities involved in carbohydrate metabolism are not substantially modified. The change in the lactate dehydrogenase isoenzyme pattern usually observed in neuroblastoma M1 cells during the different growth phases is abolished by the bromodeoxyuridine treatment. The mechanism of the inhibitory effect of bromodeoxyuridine is discussed.
REGIONAL CHANGES IN RAT BRAIN CHOLINE ACETYLTRANSFERASE AND ACETYLCHOLINESTERASE ACTIVITY RESULTING FROM UNDERNUTRITION IMPOSED DURING DIFFERENT PERIODS OF DEVELOPMENT1
Authors: Eckhert C. D. , Barnes R. H. , Levitsky D. A.
Published: October 2006

Abstract— The severity of mental changes in malnourished children is related to both the period of development when the malnutrition occurs and the amount of environmental stimulation. In the present study the effect of imposing protein undernutrition during the period of gestation or postweaning period, and protein‐energy undernutrition during the suckling period on cholinergic enzyme activity was investigated in the rat. Six different dietary treatments were given and the activity of ChAc, ChE, and AChE determined in the forebrain, brainstem, and cerebellum of male rats on day 49. Undernutrition imposed during gestation, suckling or postweaning all resulted in changes in cholinergic enzyme activity. The direction and degree of change of enzyme activity depended on the period when undernutrition was imposed as well as the brain region. In the forebrain ChE and AChE activities were altered, in the brainstem, ChAc, ChE and AChE activities were altered, and in the cerebellum ChAc activity was altered. The effect on the activity of the individual cholinergic enzymes was complex and was not the same in the different regions of the brain or even for the same brain region exposed to undernutrition during different periods of development. These results along with earlier work indicate that cholinergic enzyme activity in brain of undernourished rats can be altered by both the period of development when undernutrition is imposed and the amount of environmental stimulation.
THE MOTOR END‐PLATE SPECIFIC FORM OF ACETYLCHOLINESTERASE: APPEARANCE DURING EMBRYOGENESIS AND RE‐INNERVATION OF RAT MUSCLE
Authors: Vigny M. , Koenig Jeanine , Rieger F.
Published: October 2006

Abstract– We have solubilized three active molecular forms of AChE from rat muscle and have confirmed the presence of one of these forms (EP form, apparent sedimentation coefficient: 16 s) uniquely at the motor end‐plate regions of several skeletal muscles. This form was never detected in smooth muscle extracts. In sternocleidomastoïdian muscle it disappeared after denervation and reappeared after re‐innervation in the region where nerve and muscle had come in contact. During the embryonic development of hind leg muscles the EP form appeared on the 14th or 15th day of gestation.

The EP form of muscle AchE appears to be an excellent biochemical marker of the neuromuscular junction.
EFFECTS OF CHRONIC TREATMENT WITH AMINO‐OXYACETIC ACID OR SODIUM n‐DIPROPYLACETATE ON BRAIN GABA LEVELS AND THE DEVELOPMENT AND REGRESSION OF COBALT EPILEPTIC FOCI IN RATS
Authors: Emson P. C.
Published: October 2006

Abstract– Acute treatment of cobalt‐induced epilepsy in rats with amino‐oxyacetic acid (20‐60 mg/kg intraperitoneally) resulted in a short period (30‐90 min) of epileptic spike suppression. In contrast sodium n‐dipropylacetate (100‐400 mg/kg intraperitoneally) had no effect on spike frequencies. Chronic treatment of cobalt epileptic rats with amino‐oxyacetic acid (2.5‐10 mg/kg intraperitoneally daily) or sodium n‐dipropylacetate (200‐400 mg/kg intraperitoneally daily) elevated brain GABA concentrations significantly and reduced brain glutamate decarboxylase activity relative to control saline‐injected cobalt epileptic rats. Brain γ‐aminobutyrate aminotransferase activity was significantly reduced by chronic treatment with amino‐oxyacetic acid, whereas chronic sodium n‐dipropylacetate had no effect on brain γ‐aminobutyrate aminotransferase activity although elevating brain GABA. Amino‐oxyacetic acid (2.5‐10 mg/kg intraperitoneally per day) reduced the frequency of epileptic spikes in the secondary foci of cobalt epileptic rats. The anticonvulsant action of amino‐oxyacetic acid was most marked at 5 mg/kg intraperitoneally where a secondary focus failed to develop in treated cobalt epileptic rats. However, there was no simple relationship between the elevation of brain GABA and the anticonvulsant action of amino‐oxyacetic acid. Thus focal GABA was higher in rats given intraperitoneal amino‐oxyacetic acid (10 mg/kg) but the anticonvulsant action of amino‐oxyacetic acid was less marked at this dose. Sodium n‐dipropylacetate (200‐400 mg/kg intraperitoneally per day) had no long‐term anticonvulsant action in this model of epilepsy. It is concluded that the anticonvulsant action of sodium n‐dipropylacetate, and probably that of amino‐oxyacetic acid, is not likely to be mediated through a mechanism involving elevation of brain GABA.
CHANGES IN THE CEREBRAL METABOLISM INDUCED BY HYPER VENTILATION AT DIFFERENT BLOOD GLUCOSE LEVELS
Authors: Norberg K.
Published: October 2006

—In order to study cerebral metabolism in hypocapnia, lightly anaesthetized rats were hyperventilated to PaCO2 about 15 mm Hg for 1, 2, 5 and 30min, the brain was frozen in situ, and cortical concentrations of organic phosphates, glycolytic and citric acid cycle metabolites, and amino acids were measured. In separate experiments, animals were made hypoglycaemic prior to induction of hypocapnia. Measurements of arteriovenous differences for oxygen and glucose indicated an increased glycolytic flux and the pattern of changes in glycolytic intermediates after 1 min suggested that this was due to an activation of the phosphofructokinase step.

The pool size of citric acid cycle intermediates gradually increased with time of hypocapnia. This increase was, as in hypoxic hypoxia, related to the accumulation of pyruvate, probably via its effect on the alanine aminotransferase reaction and on the rate of CO2 fixation at the pyruvate carboxylase step. In hypoglycaemic, hypocapnic animals, in which the production of pyruvate was limited, the increase in pool size did not occur. It is suggested that the pyruvate concentration determines the net flux at the CO2 fixation step and thereby the direction of net flux of carbon skeletons between the citric acid cycle and the glycolytic chain. The changes in amino acids (glutamate, glutamine, alanine, GABA and aspartate) with time of hypocapnia were also similar to those occurring in hypoxic hypoxia. Thus, there was an increase in alanine concentration and a shift in aspartate aminotransferase reaction with increase in glutamate and fall in aspartate. It is suggested that the increase in alanine was secondary to a rise in pyruvate concentration, and that the shift in the aspartate aminotransferase reaction was due to reduction of the malate dehydrogenase system. This interpretation is supported by the fact that hypoglycaemia, by preventing a rise in pyruvate concentration and a reduction in the cytoplasmic redox system, also prevented the changes in amino acids.
ACETYLCHOLINE TRANSLOCATION IN SYNAPTIC VESICLE GHOSTS IN VITRO
Authors: Suszkiw J. B.
Published: October 2006

Abstract— Translocation of acetylcholine (ACh) into cholinergic synaptic vesicles depleted of ACh and ATP was studied by Sephadex gel filtration. The hypo‐osmotically shocked vesicles become transiently leaky, but retain ACh under iso‐osmotic conditions. Intravesicular accumulation of [3H]ACh is due to a simple diffusional equilibration. Addition of 2mM‐ATP and Mg2+ to the incubation medium is without effect. When acetylcoenzyme A (AcCoA) and choline (Ch +) are used in place of preformed ACh, the intravesicular concentration of ACh does not exceed that of the newly synthesized, extravesicular ACh. However, in the absence of Na + the quantity of [3H]ACh associated with the vesicles increased, presumably due to ACh binding to ion‐exchanger sites in the vesicles.
INTRACRANIAL CONVERSION OF LINOLEIC ACID TO ARACHIDONIC ACID: EVIDENCE FOR LACK OF Δ8 DESATURASE IN THE BRAIN
Authors: Dhopeshwarkar Govind A. , Subramanian Carole
Published: October 2006

Eleven‐day old rats were given intracranial injection of [1‐14C]linoleic acid (all cis 9,12 octadecadienoic acid) and sacrificed after 8 h. Analysis of brain fatty acids showed that 16:0, 18:2, 20:2,20:3 and 20:4 were labeled. Separation by AgN03:Si02 TLC plates followed by reductive ozonolysis characterized thc polyunsaturated fatty acids as 18:2 (Δ9,12), 20:2 (Δ11,14), 20:3 (Δ8,11,14) and 20:4 (Δ5,8,11,14). A smaller amount of 18:3 (Δ6,9,12) was also identified. This initially suggested 20:2 (A1 1,14) as an intermediate in the optional pathway of biosynthesis of arachidonate. However, when [l‐14C]eicosadienoic acid (Δ1 1,141 itself was injected in the brain it was converted to 20:3 (Δ5,11,14) (a non‐methylene interrupted double bond system) rather than the expected 20:3 (Δ8,11,14). Only a small amount of arachidonate was formed from 20:2 (Δ11,14). Thus it was concluded that 20:2 (Δ11,14) was not an intermediate in the pathways of arachidonate biosynthesis due to lack of Δ5 desaturase in thc brain which agrees with the findings of SPKECRER & LEE (1975) in rat liver.
REGIONAL BRAIN STUDY OF INDOLEAMINE METABOLISM IN THE RAT IN ACUTE HEPATIC FAILURE
Authors: Cummings M. G. , James J. H. , Soeters P. B. , Keane Jane M. , Foster J. , Fischer J. E.
Published: October 2006

Abstract— Tryptophan, 5‐hydroxytryptamine and 5‐hydroindoleacetic acid were found to be greatly increased in various parts of the brains of rats in acute hepatic failure following two stage hepatic devascularization. However, the increases in 5‐hydroxytryptamine and 5‐hydroxyindoleacetic acid varied by region and are not explicable solely in terms of increased concentrations of tryptophan. The results are discussed in terms of differences in the regional metabolism of 5‐hydroxyindoleamines. Plasma free fatty acids, albumin, total tryptophan and free tryptophan were measured in plasma in hopes of elucidating the mechanism responsible for the cerebral elevation of tryptophan. Increased plasma free tryptophan appears sufficient to explain the rapid increase in brain tryptophan. The relationship between these results and recent observations in hepatic encephalopathy is discussed.
PROPERTIES OF THE EXTERNAL ACETYLCHOLINESTERASE IN GUINEA‐PIG IRIS
Authors: Karlsen R. Lund , Fonnum F.
Published: October 2006

Abstract— The acetylcholinesterase (AChE) of intact iris, the so‐called external AChE, differs in several respects from the AChE in an homogenate of iris, called the total AChE. Maximum enzyme activities of the external and total AChE were obtained with an ACh concentration of 10 and 1.3 mm, respectively. The total AChE exhibited substrate inhibition at high substrate concentrations, whereas the external enzyme did not exhibit substrate inhibition in the range studied. The external AChE activity, when measured at 1.3 mm‐ACh. accounted only for 12% of the total enzyme activity. After irreversible inhibition of AChE with diisopropylfluorophosphate (DFP) or methylisocyclopentylfluorophosphate (soman) the external AChE recovered to almost normal values after 48 h, whereas only 30% of the total AChE recovered during this period. Pupillographic studies after inhibition with DFP demonstrated that pupillary diameter had reached normal size after 24 h.

Destruction of the cholinergic input to iris reduced the total AChE activity by 40%, but did not alter the external AChE activity nor its rate of recovery after DFP inhibition. The specific activities of total AChE and total choline acetyltransferase were significantly higher in the sphincter than in the dilator muscle. After such denervation of iris the greatest reduction in total AChE and choline acetyltransferase were found in the sphincter region. After treatment with DFP the total AChE was inhibited to the same extent and recovered at the same rate in both regions.

After extraction of AChE from iris with various salt solutions and detergents, the particulate enzyme recovered faster than the soluble enzyme from DFP inhibition.
UPTAKE OF GLUCOSE ANALOGUES BY RAT BRAIN CORTEX SLICES: MEMBRANE TRANSPORT VERSUS METABOLISM OF 2‐DEOXY‐d‐GLUCOSE
Authors: Lund‐Andersen H. , Kjeldsen Christel S.
Published: October 2006

Abstract— —The uptake of the glucose analogue 2‐deoxy‐d‐glucose by rat brain cortex slices was studied in order to compare the rate of membrane transport with the rate of phosphorylation in the concentration range 5–12 mM‐glucose plus 0.5–15 mM‐2‐deoxy‐glucose. The comparison was carried out by fitting a model of the brain slice to uptake data and by determination of 2‐deoxy‐glucose and 2‐deoxy‐glucose‐6‐phosphate by ion exchange chromatography.

The rate of membrane transport exceeded the rate of phosphorylation by at least one order of magnitude. The membrane transport was so rapid that the extracellular diffusion became rate limiting for the uptake. The membrane transport could therefore only be determined as a minimum value and it was not possible to determine unidirectional flux across the cell membranes (initial rate). Accordingly, characterization of the membrane tranport with respect to maximal transport rate and affinity was not possible. The phosphorylation reaction, however, was so slow that it was accessible for exact determination and only the phosphorylation reaction was responsible for the fact that the cellular uptake of 2‐deoxy‐glucose was of the Michaelis‐Menten type, thus emphasizing the importance of dissociation between membrane transport and metabolism when transport is studied of a substance which can undergo metabolism.

The data indicate that glucose transport across glial and neuronal membranes is not rate limiting for glucose metabolism of brain tissue in vitro.
REVERSAL OF AXONAL TRANSPORT AT A NERVE CRUSH1
Authors: Bisby M. A. , Bulger V. T.
Published: October 2006

Abstract— —We have compared retrograde axonal transport of 3H‐labeled protein in normal rat motor and sensory axons, and axons which were injured by a distal ligation of the sciatic nerve. After injection of L‐[3H]leucine into the vicinity of the neuron cell bodies, labeled protein was transported into the axons. A premature return of protein towards the cell bodies occurred in the injured axons, which we interpret as a reversal of axonal transport occurring at the site of injury. We estimate that reversal of transport occurred within 1.9–2.4 h of the arrival of labeled protein at the injury, and that the minimum velocity of the subsequent retrograde transport was 112–133 mm day−1. The ability of the injured axons to reverse transport developed about 0.8 h after making the injury. A large fraction of the orthograde transported protein was returned towards the cell body: it is estimated that by 28 h after labeled protein in sensory axons reached the injury, 46% of the3H‐labeled protein originally transported to the injury site had been returned. In intact sensory nerves at this time only 15% of the transported protein had returned. It is suggested that axonal injury produces a sudden increase in the return of newly synthesized protein to the cell body, and that this might serve as a signal for chromatolysis.
EFFECT OF ALBUMIN BINDING AND AMINO ACID COMPETITION ON TRYPTOPHAN UPTAKE INTO BRAIN1
Authors: Yuwiler A. , Oldendorf W. H. , Geller E. , Braun L.
Published: October 2006

Abstract— In the present study we examine the influence of pH, palmitate, and neutral amino acids on the passage of tryptophan from blood into brain during a single capillary pass, and on the partitioning of tryptophan between free and albumin‐bound forms. The results show that a considerable fraction of albumin‐bound tryptophan is stripped from albumin sites during passage, that uptake is concentration‐dependent, and that amino acid competition for carrier sites is quantitatively the most important factor in regulating tryptophan uptake into brain. The interaction between tryptophan concentration, tryptophan binding, and competing amino acids is of considerable influence on brain serotonin biosynthesis.
AMINO ACID CONCENTRATIONS IN THE APLYSIA NERVOUS SYSTEM: NEURONS WITH HIGH GLYCINE CONCENTRATIONS
Authors: Iliffe T. M. , McAdoo D. J. , Beyer Carol B. , Haber B.
Published: October 2006

Abstract— The levels of the amino acids glycine, aspartic acid and glutamic acid were determined in the ganglia and in identified neurons of A. californica. All of the determinations were done by gas chromatography–mass spectrometry–selected ion monitoring using deuterium‐labelled amino acids as internal standards. Aspartate and glutamate concentrations vary 2‐ to 3‐fold among the ganglia and individual neurons. Glycine levels are 3–10 times higher in the abdominal ganglion than in the other ganglia. This is in large part due to the glycine concentrations in the abdominal ganglion neurons R3–R14 being about 20 times higher than in the somata of most other Aplysia neurons. The concentrations of all three amino acids are several times lower in the muscle than in ganglia, and orders of magnitude lower in the hemolymph than in tissue.
EFFECTS OF γ‐BUTYROLACTONE ON LOCAL CEREBRAL GLUCOSE UTILIZATION IN THE RAT
Authors: Wolfson L. I. , Sakurada O. , Sokoloff L.
Published: October 2006

Abstract— The effects of graded doses of γ‐butyrolactone on the rates of glucose utilization in 29 structural components of the albino rat brain were studied by means of the [14C]deoxyglucose technique. The γ‐butyrolactone in doses of 75, 150, 300, and 600 mg/kg of body weight was administered intravenously in divided doses, two‐thirds 45min and one‐third 15min before the administration of the pulse of [14C]deoxyglucose. Electroencephalographic recordings were carried out in some of the rats administered each of the above doses. The results demonstrate dose‐dependent changes in the level of consciousness, electroencephalographic activity, and the rates of local cerebral glucose utilization. At the two lower doses there were no notable effects on behavior, but there was significant slowing of the electroencephalogram. The higher doses caused a trance‐like state associated with long periods of electroencephalographic silence punctuated by bursts of polyspike and wave activity. At all doses there was significant depression of the rates of cerebral glucose utilization throughout the brain, the greater the dose the greater the magnitude of the depression. The effects were greater in gray structures than in white matter. At the maximum doses local cerebral glucose utilization was profoundly depressed to mean values of 32% and 58% of control values in gray and white matter, respectively. There was no apparent selectivity or specificity in the effects of γ‐butyrolactone on glucose utilization in the various gray structures of the brain; all 26 gray structures studied exhibited similar dose‐response relationships. Animals similarly treated with γ‐butyrolactone and left undisturbed regained completely normal behavior and electroencephalographic activity in several hours. These results suggest that γ‐butyrolactone profoundly depresses cerebral energy metabolism throughout the brain and that it might prove useful in clinical conditions in which a temporary reversible reduction in cerebral energy demand is desired.
STUDIES ON RAT SPINAL CORD POLYSOMES: POSTNATAL DEVELOPMENT AND EXPERIMENTAL DEMYELINATION1
Authors: Chiu Fung‐Chow , Smith Marion Edmonds
Published: October 2006

Spinal cord polysomes were prepared from 15‐day‐old rats, 3‐month‐old rats, and adult triethyl tin‐fed and control rats by a procedure adapted from that of Zomzely‐Neurathet al. (1973) for brain polysomes. The state of aggregation and the activity in a cell‐free system supplemented with a hepatic enzyme fraction were studied with these preparations. The properties of the amino acid‐incorporating system in spinal cord polysomes were similar to those of brain systems with respect to rapid incorporation in the first 30 min of incubation, dependence on polysomes and supplementary enzymes, sensitivity to emetine and high Mg2+, and relative insensitivity to cycloheximide. Polysomes from 15‐day‐old rats were more highly aggregated than those from 3‐month‐old rats, but incorporation of radioactive amino acids was not different in the preparations from the two age groups with respect to the requirement for the supplementary enzyme fraction or the kinetics. Spinal cord polysomes prepared from rats with chronic triethyl tin‐induced edema and demyelination were slightly more aggregated than those from the controls. Average increases of 30% in amino acid incorporating activity were observed in spinal cord polysomes from triethyl tin‐fed rats compared to those of controls. Similar increases have been shown previously in fractions from the spinal cord slice, especially in the myelin fraction (Smith, 1973). Spinal cord polysomes from rats in two stages of development and in different experimentally‐caused physiological states behaved differently within the limits of our in vitro system.
NIEMANN PICK DISEASE: PRESENCE OF THE MAGNESIUM‐DEPENDENT SPHINGOMYELINASE IN BRAIN OF THE INFANTILE FORM OF THE DISEASE1
Authors: Gatt S. , Dinur T. , Kopolovic J.
Published: October 2006

Abstract— Brain of a 14‐month‐old patient with the infantile form of Niemann Pick disease was found to be practically devoid of sphingomyelinase activity when assayed at pH 5. When assayed at pH 7.4, in the presence of magnesium ions considerable hydrolysis of sphingomyelin was obtained by brain preparations. The rate of hydrolis of a homogenate of grey matter was about 0.3 μmol. mg protein−1. H−1, corresponding to about 15 μmol of sphingomyelin hydrolysed perg brain in 1 h.

The possibility is suggested that the presence of the extra‐lysosomal, magnesium dependent sphingomyelinase in brain of Niemann Pick patients may be responsible, in part, for the lesser accumulation of sphingomyelin in this tissue relative to other organs, such as liver or spleen.
CALCIUM‐DEPENDENT BINDING OF BRAIN GLUTAMATE DECARBOXYLASE TO PHOSPHOLIPID VESICLES
Authors: Covarrubias Manuel , Tapia Ricardo
Published: October 2006

The binding of glutamate decarboxylase (GAD), to phospholipid vesicles (liposomes) in the absence and in the presence of several Ca2+ and Mg2+ concentrations was studied. Phosphatidylcho‐line‐phosphatidylserine (4:1) liposomes are capable of binding GAD in a Ca2+‐dependent manner. The per cent of GAD bound increased from 5 to 65°., in a sigmoid shape with Ca2+ concentrations in the 0.2‐4 mm range. Mg2+ also induces GAD binding but is less effective than Ca2+ The Ca2+ ‐dependent binding of GAD is not the result of unspecific association of protein, since Ca2+ did not promote any binding of choline acetyltransferase or lactate dehydrogenase. Furthermore, the relative specific activity (oo enzyme activity/% protein) of GAD associated to liposomes increases 4‐fold from 0 to 2 mm Ca2+. The per cent of GAD bound attains a plateau at a ratio phospholipid/protein of about 1.5. and decreases when the pH increases from 6.5 or 6.8 to 7 or 7.25. Na+ or K+ at a 100mm concentration also induce binding of GAD to liposomes. Phosphatidylcholine liposomes (without phosphatidylserine) practically did not bind GAD at any Ca2+ concentration. The Ca2+‐dependent association of GAD to phosphatidylcholine‐phosphatidylserine liposomes is very similar to that previously reported using brain membranes, and it correlates also well with the reported Ca2+‐dependent aggregation of phosphatidylserine molecules in phospholipid membranes of similar composition. It is concluded that phosphatidylserine is probably involved in the Ca2+‐dependent binding of GAD to brain membranes. Phospholipid vesicles seem to be a useful experimental model for studying the mechanisms of this GAD association to membranes and the possible physiological implications of the GAD‐Ca2+‐membrane interaction regarding the release of newly synthesized GABA from nerve endings.
RELEASE OF ATP FROM A SYNAPTOSOMAL PREPARATION BY ELEVATED EXTRACELLULAR K+ AND BY VERATRIDINE
Authors: White T. D.
Published: October 2006

Abstract—

A technique was developed which permitted the release of ATP from synaptosomes by elevated extracellular K+ or by veratridine to be directly and continuously monitored. The released ATP interacted with firefly luciferin and luciferase in the incubation medium to produce light which could be detected by a photomultiplier. The assay system was specific for ATP, in that similar concentrations of adenosine, AMP or ADP did not produce chemiluminescence. Moreover, the maximum peak of light emission correlated linearly with the concentrations of ATP present in the medium, so that semiquantitative estimates of ATP release could be made.

Elevating the extracellular K+ concentration produced a graded release of ATP from synaptosomes. Rb+ also released ATP but Na+, Li+ and choline did not. The response to elevated K+ was not blocked by tetrodotoxin (TTX), indicating that this effect was not mediated by the opening of Na+‐channels in synaptosomal membranes.

Veratridine (50 μM) caused a graded release of ATP which was larger and more prolonged than that caused by elevated K+. The release of ATP by veratridine was blocked by TTX indicating that the opening of Na+‐channels was involved. Neither veratridine nor elevated K+ released ATP from microsomal or mitochondrial fractions, showing that the release of ATP probably did not originate from microsomal, vesicular or mitochondrial contaminants of the synaptosomal preparation.

Release of ATP by elevated K+ was diminished in a medium lacking CaCl+ or when EGTA was added to chelate Ca2+. In contrast, release by veratridine appeared to be augmented in Ca2+‐free media or in the presence of EGTA.

The K+‐induced release of ATP, which is Ca2+ dependent, closely resembles the exocytotic release of putative neurotransmitters from presynaptic nerve‐terminals. On the other hand, the apparent lack of a Ca2+ requirement for veratridine's action suggests that this process could originate from other sites, or involve mechanisms other than conventional neurotransmitter release processes.
RESTITUTION OF CEREBRAL ENERGY STATE, AS WELL AS OF GLYCOLYTIC METABOLITES, CITRIC ACID CYCLE INTERMEDIATES AND ASSOCIATED AMINO ACIDS AFTER 30 MINUTES OF COMPLETE ISCHEMIA IN RATS ANAESTHETIZED WITH NITROUS OXIDE OR PHENOBARBITAL
Authors: Nordström C.‐H. , Rehncrona S. , Siesjö B. K.
Published: October 2006

Abstract—

Restitution of cerebral cortex concentrations of organic phosphates, glycolytic metabolites, citric acid cycle intermediates, associated amino acids, and ammonia, following a 30 min period of complete ischemia, was studied in rats anaesthetized with either 70% N2O or 150 mg·kg‐1 of phenobar‐bital.

Following a 90 min period of recirculation the pattern of restitution was similar in the two groups. Thus, all animals showed recovery of phosphocreatine concentrations, restitution of the adenylate energy charge to about 99% of control, and disappearance of lactate accumulated during the ischemia. Analyses of glycolytic metabolites indicated inhibition of glycolysis at the phosphofructokinase step, possibly caused by accumulation of citrate. Measured citric acid cycle intermediates indicated extensive normalization of mitochondrial metabolism. Changes in amino acid concentrations consisted of a fall in glutamate concentration, a rise in aspartate/glutamate ratio, a fall in GABA concentration, and a rise in alanine concentration. However, ammonia concentration was close to normal, and the size of the amino acid pool did not change.

It is concluded that although the results do not exclude damage to a small part of the neuronal population, they demonstrate that, irrespective of the type of anaesthesia used, the majority of brain cells must have survived 30 min of complete ischemia without signs of irreversible metabolic damage.
IN VITRO BIOSYNTHESIS OF TUBULIN ON TOTAL, FREE AND MEMBRANE‐BOUND POLYSOMES FROM THE DEVELOPING RAT BRAIN
Authors: Sato M. , Yoshida Y. , Takahashi Y.
Published: October 2006

Abstract— Incorporation of [3H]leucine into tubulin and total protein was examined using a polysomal system from newborn (1‐day‐old). young (10‐day‐old) and adult (3‐month‐old) rat brains and cerebral cortices. The rate of tubulin biosynthesis (specific radioactivity) was always lower than that of total protein biosynthesis. No significant differences in the specific radioactivities of the synthesized total proteins were found between the newborn and young brain polysomal system, although young cerebral cortical polysomes were less active than newborn cerebral cortical polysomes. The adult brain (or cerebral cortical) polysomes were less active, about 20‐30% lower than the young brain (or cerebral cortical) polysomes. The incorporation of [3H]leucine into tubulin showed a progressive decrease in the polysomal systems isolated from the newborn, young and adult rat brains and cerebral cortices. These tendencies were similar in every cell sap taken from newborn, young and adult rat brain homogenates.

In order to examine the relative activities of free and bound polysomes of the developing rat brain in tubulin biosynthesis. double‐labelling experiments were carried out. Labelled tubulin was purified by the assembly and disassembly method, followed by SDS gel electrophoresis, or by vinblastine precipitation method, followed by SDS gel electrophoresis; then identification by co‐electrophoresis with native brain tubulin, molecular weight determination and demonstration of specific aggregation in the presence of GTP followed. Free and bound polysomes showed approximately similar activities during tubulin biosynthesis. Furthermore, relative activities of tubulin biosynthesis by free and bound polysomes did not significantly change during development.
GLUTAMINE—A MAJOR SUBSTRATE FOR NERVE ENDINGS
Authors: Bradford H. F. , Ward H. K. , Thomas A. J.
Published: October 2006

Abstract— Mammalian cortical synaptosomes incubated in the presence of glucose (2.5 MM) plus glutamine (0.5 mM) showed a 30% increase in transmitter amino acid content over controls with glucose alone and a doubling of glutamate release induced by Veratrine or high K+. Double‐label experiments, i.e. [U‐14C]glucose with [3H]glutamine, and single‐label experiments, i.e. [U‐14C]glucose or [U‐14C]‐glutamine showed that stimulus‐released glutamate was derived principally (80%) from glutamine. Released glutamine‐derived glutamate was of higher (x 2) specific radioactivity than its tissue equivalent. Glutamine alone (0.5–0.75 mM) was much less effective than equivalent amounts of glucose alone, in stimulating respiration and maintaining tissue K+ levels.
EXISTENCE OF ASCORBIC ACID AS AN ACTIVATOR OF THIAMINE DlPHOSPHATASE IN RAT BRAIN
Authors: Matsuda T. , Maeda S. , Baba A. , Iwata H.
Published: October 2006

Abstract—

The effect of the supernatant fraction (105,000 g for 60 min) of rat brain on the microsomal thiamine diphosphatase activity was examined. The thiamine diphosphatase activity was increased by addition of the supernatant fraction. The factor activating the enzyme was a heat‐stable and dialyzable substance. It caused lipid peroxidation in the microsomes and the increase of the enzyme activity was mediated through lipid peroxidation of the preparation. When the supernatant fraction was chromatographed on columns of Sephadex G‐25 and Dowex 1 × 2, the activator was eluted in fractions containing ascorbic acid. The inhibitory factor of ATPase present in the supernatant fraction was also eluted with the activator. The u.v.‐spectrum of the active fraction obtained by these chromatographies was the same as that of ascorbic acid. These findings indicate the existence of ascorbic acid as an activator of thiamine diphosphatase in rat brain and confirm the previous finding that the soluble factor inhibiting ATPase activity is ascorbic acid.
POST MORTEM STABILITY AND STORAGE IN THE COLD OF BRAIN ENZYMES
Authors: Puymirat J. , Javoy‐Agid F. , Gaspar P. , Ploska A. , Prochiantz A. , Agid Y.
Published: October 2006

Abstract—

Tyrosine hydroxylase (TH), glutamate‐decarboxylase (GAD) and choline acetyltransferase (CAT) were estimated in the striatum of rat brains kept at 20°C or 4°C for various periods of time up to 48 h after death. At 20°C TH and GAD activities decreased up to 4&50% of controls after 48 h; CAT activity was not affected. Maintenance of dead animals at 4°C completely (GAD and CAT) or partially (TH) prevented the decrease in enzyme activities. In a second series of experiments, TH, G A D and CAT activities were measured in striata (tissue or homogenate) stored immediately after death at different temperatures (4°C; ‐35°C; ‐70°C) for various time intervals up to 3 months. Storage of striata at 4°C induced a rapid decrease of all enzyme activities with time (GAD > CAT > TH). TH, GAD and CAT activities in striata kept at ‐35°C or ‐70°C were fairly stable. However, CAT activity was slightly decreased when the dissected striata were not homogenized; GAD activity was substantially reduced after 3 months at ‐35°C. Stability of TH, GAD and CAT activities were confirmed in homogenates of human caudate nucleus stored at ‐70°C for 1 month.

If human enzymes behave similarly to the rat enzymes the following conclusions should be drawn: (1) brains should be obtained at autopsy within 8 h after death; (2) placement of dead bodies in the refrigerator should be done as soon as possible; (3) dissected brain structures (preferably as homogenates) should be stored at ‐70°C.
EFFECTS OF NERVE GROWTH FACTOR ON CYCLIC AMP LEVELS IN EMBRYONIC CHICK DORSAL ROOT GANGLIA FOLLOWING FACTOR DEPRIVATION
Authors: Skaper S. D. , Bottenstein J. E. , Varon S.
Published: October 2006

Nerve growth factor (NGF) at 10 B.U./ml produced a 5‐fold increase in the concentration of cyclic AMP 10min after addition to freshly excised embryonic chick dorsal root ganglia (DRG). The presence of NGF at 10 B.U./ml, but not 1 B.U./ml, over a 6 h incubation in nutrient‐free medium prevented this cyclic AMP increase when the DRG were again challenged with NGF (10 B.U./ml) after the 6 h. Incubation of DRG for 6 h at 37°C without NGF did not prevent the cyclic AMP response from occurring when NGF was presented at this time. The basal cyclic AMP concentration, however, decreased by 65–75% during the course of the 6 h incubation, and the continuous presence of NGF (10 B.U./ml) was unable to prevent this. When NGF was added to 6‐h NGF‐deprived DRG, the time for maximum cyclic AMP increase decreased from 15min to 6min with increasing NGF concentrations from 1 to 50 B.U./ml, although the relative magnitude of the cyclic AMP increase was essentially the same (approx 3‐fold) at these NGF concentrations.

Attempts were made to correlate the cyclic AMP response in NGF‐deprived DRG with another rapid response resulting from administration of NGF to NGF‐deprived DRG, namely, the reactivation of hexose uptake. The cyclic AMP and permeation responses both occurred on the same time scale (5‐15 min), and both responded to increasing concentrations of NGF with a decreasing time to achieve maximal effect. A temporal relationship between cyclic AMP and membrane permeability was noted, but it could not be ruled out that it might reflect difficulties in methodology and/or inadequacy in current knowledge of the underlying mechanisms.
TURNOVER OF FREE AND CONJUGATED (SULPHONYLOXY) DIHYDROXYPHENYLACETIC ACID AND HOMOVANILLIC ACID IN RAT STRIATUM
Authors: Dedek J. , Baumes R. , Ten‐Duc N. , Gomeni R. , Korf J.
Published: October 2006

Abstract— Conjugated (sulphonyloxy) dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) were synthesized from free DOPAC and HVA and used as reference compounds in their fluorimetric determination in rat brain (detection limit 0.2 nmol/g). The conjugated DOPAC and HVA form 29 and 36% of the total DOPAC and HVA found in rat striatum, respectively. Dopamine (DA) metabolism was studied in the rat striatum by following the decline of both free and conjugated DOPAC and HVA after treatment with pargyline (100mg/kg. i.p.) either alone or in combination with tropolone (100 mg/kg, i.p.). or from the accumulation of the free and conjugated acids after treatment with probenecid (100‐500mg/kg. i.p.). The rates of decline were analysed by a non‐linear curve fitting method using a simple model of DA metabolism that postulates the formation of the conjugates exclusively from the free acids, and HVA from DOPAC, with first order kinetics and single open compartments only. The curves computed all passed through the s.e.m. of every experimental point. The rate constants thus found indicate that DOPAC turnover is about 23nmol/g/h. Of this about 16 nmol/g/h are O‐methylated to HVA, about 6 nmol/g/h are conjugated and less than 1 nmol/g/h is eliminated as free DOPAC. Of the HVA formed, about 8.5nmol/g/h are conjugated and about 7.5 nmol/g/h eliminated as free HVA. The conjugates accumulated after treatment with probenecid (1 h) faster than the free acids. The maximal accumulation of all four metabolites found (21 nmol/g/h) approximates the total turnover of DOPAC.
ACYLATION OF LYSOPHOSPHATIDYLSERINE BY RAT BRAIN MICROSOMES
Authors: James O. A. , MacDonald G. , Thompson W.
Published: October 2006

Abstract— The acylation of lysophosphatidylserine, prepared by snake venom digestion of phosphatidylserine, by rat brain microsomes is described. Acylation was monitored by spectrophotometric assay and by measuring the incorporation of radioactively labelled acyl CoA thioesters. Acylation was time dependent, showed an approximately linear response to enzyme concentration and had a pH optimum of 9.0. Maximum acylation was attained at a concentration of about 100 μM for lysophosphatidylserine and about 40μM for acyl CoA thioesters. Positional distribution studies with [14C]oleoyl CoA and [14C]arachidonoyl CoA showed incorporation was predominantly at position ‐2, but with significant labelling at position–1, particularly with oleoyl CoA, possibly as a result of isomerization of the 1–acyl isomer of lysophosphatidylserine. Both saturated and unsaturated thioesters could serve as acyl group donors. Myristoyl CoA was considerably superior to palmitoyl CoA and stearoyl CoA, which were poor acyl group donors. Some selectivity was shown among the long chain unsaturated thioesters, linoleoyl, linolenoyl and arachidonoyl CoA being the most effective acylating agents. Although docosahexaenoic acid is a major unsaturated fatty acid in brain phosphatidylserine, its CoA ester was a relatively poor acyl group donor. Relative acylation rates remained essentially constant over a wide range of lysophosphatidylserine concentrations. It is concluded that acyl transfer mechanisms are active in brain for the regulation of the fatty acid profile of phosphatidylserine.