bluuebunny/crossref_metadata_2025 huggingface dataset:
STIMULATORY EFFECT OF γ‐AMINOBUTYRIC ACID UPON AMINO ACID INCORPORATION INTO PROTEIN BY A RIBOSOMAL SYSTEM FROM IMMATURE RAT BRAIN1
Authors: Tewari S. , Baxter C. F.
Published: October 2006

Abstract—

GABAstimulated the incorporation of L‐[U‐14C]leucine, primarily into the particulate protein of a ribosomal system from immature rat brain, but not from immature rat liver.

The GABA effect required the presence of Na+ and occurred at GABA concentrations which are thought to be physiological (1–5 mM).

Of all other amino acids tested at tissue extract concentrations in the system, only glycine had a similar effect. No analogues of GABA tested had a significant stimulatory effect upon leucine incorporation into protein, with the exception of homocarnosine which was mildly stimulatory.

The effect of GABA upon the incorporation of L‐[U‐14C]leucine was examined in the presence of added amino acid substrates, both individually and as mixtures. Also, the incorporation of L‐[U‐14C]leucine was compared with incorporation of L‐[U‐14C]Iysine and L‐[U‐14C]phenylalanine. The results are discussed in terms of GABA interaction with activating, transfer and transport mechanisms of other amino acids, inhibition of proteinase activity, and the possibility that GABA is stimulating the synthesis or turnover of specific proteins in the brain ribosomal system.

The results illustrate the fact that studies of ‘protein synthesis’ in immature rat brain ribosomes, as measured by amino acid incorporation, will yield answers which depend heavily upon substrate conditions and upon the labelled amino acid used as the marker for protein synthesis or turnover.
THE ACTION IN VIVO OF A STRUCTURAL ANALOGUE OF GABA: HYDRAZINOPROPIONIC ACID1
Authors: Van Gelder N. M.
Published: October 2006

Abstract— The action of hydrazinopropionic acid in vivo on the metabolism of amino acids in the CNS of mice was studied over a period of 24 hr. At 82 μmoles/kg, a transient fourfold rise in the levels of tyrosine occurred followed by a more moderate and prolonged increase in the levels of GABA. When the dose of hydrazinopropionate was raised to 123 μmoles/kg, the changes in the levels of tyrosine were identical with those at the lower dose, while levels of GABA rose further before reaching a steady state. Levels of glutamate decreased concomitantly. In addition, the concentrations of alanine, β‐aminoisobutyric acid and an unknown compound tended to rise. A doubling of the dose to 246 μmoles/kg enhanced the effects obtained with the lower doses but did not produce any new changes in the patterns of amino acids of the CNS.

The elevation in the concentrations of alanine paralleled changes in the levels of tyrosine. The changes in the concentrations of the unknown compound, tentatively identified as α‐aminoadipate, and of β‐aminoisobutyric acid resembled those of GABA. The results are interpreted to indicate an inhibition by hydrazinopropionic acid of tyrosine aminotransferase and aminobutyrate aminotransferase.
ACTIVATORS and INHIBITORS OF BRAIN GLUTAMINASE
Authors: Weil‐Malherbe H.
Published: October 2006

Abstract—

(1) The glutaminase activity of a guinea pig brain dispersion (a 1500g supernatant solution) was tested at pH 7.5 in the presence of a series of organic acids at 20 mm with or without the further addition of 7.5 mm‐phosphate.

(2) In the absence of phosphate, glutaminase activity was strongly enhanced by tricarboxylic acids, less strongly by dicarboxylic acids, and slightly, if at all, by monocarboxylic acids. Acidic amino acids were intermediate between mono‐ and dicarboxylic acids. In the presence of 7.5 mm‐phosphate, the addition of 20 mm organic acids resulted in strong potentiation of the activating effect in many cases. The activating effect of even the most active of the organic acids tested, citrate, was only about half of the effect of an equimolar amount of phosphate.

(3) At phosphate concentrations approaching the saturation level for activation, the further addition of citrate was without effect.

(4) Glutaminase was strongly activated by ITP which was about three times as active as inorganic phosphate. IMP was less active than inorganic phosphate and creatine phosphate had only slight activity which seemed to be accounted for by its content of inorganic phosphate.

(5) Glutaminase was activated by fluoride, in the presence as well as in the absence of added phosphate. Chloride, bromide, and iodide, at 100 mm, produced increasing inhibition of the phosphate‐activated reaction. The inhibiting effect of iodide was qualitatively competitive with phosphate.

(6) The effects of various other potential inhibitors and activators, including SH‐reagents, d‐glutamine, several amino acids, and amino acid derivatives were studied.

(7) The results have been discussed with particular reference to their significance in elucidating the natural function of brain glutaminase. It has been suggested that glutaminase is an allosteric enzyme and that the secondary active site requires a reaction with three anionic groups for full activation.
HYDROLASE ACTIVITIES IN BRAIN OF NEUROLOGICAL MUTANTS: CEREBROSIDE GALACTOSIDASE, NITROPHENYL GALACTOSIDE HYDROLASE, NITROPHENYL LUCOSIDE HYDROLASE AND SULPHATASE1
Authors: Bowen D. M. , Radin N. S.
Published: October 2006

Abstract—

The brains of 17‐day‐old quaking and jimpy mice were compared with those of the corresponding normal phenotypes. The concentrations of cerebroside and sulphatide were found to be markedly lower in the affected mutants, while the relative amounts of ceramide and free fatty acid appeared normal.

The concentration of cerebroside glactosidase was not significantly abnormal in the jimpy mice but was about 17 per cent lower in quaking mice. In contrast, the relative amount of the enzyme that could be dispersed by sonication was considerably higher in the jimpy animals. It is suggested that this increase is a causative factor in the aetiology of the latter disease.

The concentrations of other acid hydrolases were determined, as well as the relative amounts dispersible by sonication. No difference was seen between the phenotypes with NPGalH, NPGluH, and nitrocatechol sulphate hydrolase.

An improved solvent system for the TLC detection of ceramide in brain lipids is described.
MERCAPTOPROPIONIC ACID: A CONVULSANT THAT INHIBITS GLUTAMATE DECARBOXYLASE1
Authors: Lamar C.
Published: October 2006

—3‐Mercaptopropionic (MP) and 4‐mercaptobutyric (MB) acids caused convulsions in rats after the intraperitoneal administration of 32 and 200 mg/kg body wt. respectively. These compounds competitively inhibited glutamate decarboxylase (L‐glutamate 1‐carboxy‐lyase; EC 4.1.1.15) of rat brain and bacterial GABA transaminase (4‐aminobutyrate: 2‐oxoglutarate aminotransferase; EC 2.6.1.c). Glutamine synthetase (L‐glutamate: ammonia ligase (ADP); EC 6.3.1.2) was not affected. Pyridoxal phosphate added in vitro did not reverse the inhibition. Action of these compounds is compared to methionine sulphoximine, a bacterial exotoxin (lactylaminopimelic acid) and to hydrazinopropionic acid.
CEREBRAL PROTEINASES IN THE GROWING RAT1
Authors: Oja S. S. , Oja Hely
Published: October 2006

—The proteolytic activity of brain homogenates obtained from 1‐, 5‐, 14‐, 60‐, 150‐, and 300‐day‐old rats was assayed with urea‐denatured haemoglobin and casein, endogenous tissue proteins, Nα‐benzoyl‐dl‐arginine 2‐naphtylamide (BANA), Nα‐benzoyl‐dl‐arginine methyl ester (BAME), Nα‐toluene p‐sulphonyl‐dl‐arginine methyl ester (TAME), Nα‐benzoyl‐dl‐phenylalanine 2‐naphthyl ester (BPANE), and Nα‐acetyl‐dl‐tyrosine ethyl ester (ATEE) as substrates.

Several peaks of activity were detected with all these substrates in different pH ranges. Activity was highest with protein substrates at pH 3·0‐4·0, with smaller peaks of activity at pH 5·5‐6·5 and 8·0‐9·0. At pH 3·0 the activity with trypsin substrates, viz. BANA, BAME and TAME, was also relatively high, but much less with chymotrypsin substrates, ATEE or BPANE. With BAME, TAME, BPANE and ATEE the hydrolysis rate was highest at neutral or slightly alkaline pH. During postnatal development the hydrolysis of protein substrates increased three‐fold at pH 3·0 and about two‐fold at pH 6·5 and 8·5. The rate of hydrolysis of BANA, BAME and TAME generally increased during the first 2 postnatal weeks and thereafter decreased, whereas no marked increase in the rate of hydrolysis of BPANE and ATEE occurred until the age of about 2 weeks. The results were less consistent with synthetic substrates than with protein substrates, indicating the existence of non‐uniform alterations during development in the activity of the individual hydrolytic enzymes participating in the breakdown of brain proteins.
THE PROTEIN COMPOSITION OF ISOLATED MYELIN1
Authors: Gonzalez‐Sastre F.
Published: October 2006

—Three fractions, each containing markedly different proteins, was obtained from myelin:

(1) The first fraction was obtained as an insoluble residue when myelin was extracted with neutral chloroform‐methanol (CM, 2:1, v/v). It was digestible with trypsin and had an amino acid composition similar to that of the acidic proteolipid protein of Wolfgkam (1966).

(2) The second fraction was obtained as a precipitate by the addition of various electrolytes (KCl, NaCl, CaCl2, MgCl2 or HCl) to the CM (2:1 v/v) extract. This fraction consisted mainly of a basic protein which exhibited an electrophoretic mobility and amino acid composition indistinguishable from those of the basic protein obtained from white matter (Martensson and LeBaron, 1966). This procedure provided for a simple and rapid isolation of the basic protein from myelin. Depending on the conditions of precipitation, this fraction was either free of lipid or contained tri‐ and diphosphoinositide. The effects of different ions at differing concentrations and the yield and nature of the precipitate have been studied.

(3) A third fraction remained in solution in CM (2:1, v/v) after the addition of the electrolyte. It comprised the bulk of the myelin lipids and a protein fraction which was resistant to digestion with trypsin and had an amino acid composition similar to the classical proteolipid protein of Folch‐Pi and Lees (1951).

The possibility of a salt‐type bonding between the basic protein and the polyphosphoinositides is discussed, and values for tri‐ and diphosphoinositide in bovine myelin are given.
QUANTITATIVE HISTOCHEMISTRY OF ACETYL‐CHOLINESTERASE IN RAT HIPPOGAMPAL REGION CORRELATED TO HISTOCHEMICAL STAINING
Authors: Storm‐Mathisen J.
Published: October 2006

Abstract— The quantitative histochemistry of acetylcholinesterase (AChE) has been examined in hippocampus (regio superior) and area dentata. Samples (0–05–2 μg) were dissected from freeze‐dried tissue sections and assayed by either a colorimetric or a radiometric micromethod. In hippocampus the highest AChE activity occurred in a narrow zone just beneath the layer of pyramidal cells. Stratum oriens had a higher activity than stratum radiatum. A small peak of activity occurred in the lacunosal layer. In area dentata the overall activity was about 60 per cent higher than in the hippocampus. The highest activities were found in two zones adjacent to the granular layer.

When the results were expressed as activities per volume of tissue they correlated well with microdensitometric measurements on sections stained for AChE by the Koelle method.

Following transection of the fimbria the activity decreased to a low level, approaching a common value in the layers examined.

The results are discussed in relation to the significance of AChE in the hippocampal region.
PHYSICAL PROPERTIES OF THE BOVINE ENCEPHALITOGENIC PROTEIN; MOLECULAR WEIGHT AND CONFORMATION1
Authors: Chao L.‐P. , Einstein Elizabeth Roboz
Published: October 2006

Abstract— The highly basic encephalitogenic protein isolated from bovine spinal cord was studied by various physicochemical methods:

The molecular weight was determined by sedimentation equilibrium, by calculation from the data on sedimentation coefficients and intrinsic viscosities, by measurement of intrinsic viscosity in the presence of concentrated guanidine hydrochloride (according to the method of Tanford, Kawahara and Lapanie, 1967), and by exclusion chromatography on Sephadex G‐100 columns. All values obtained were in good agreement and indicated a molecular weight of approximately 18,000–20,000.

Studies of sedimentation velocities in the presence and absence of 6 m‐guanidine‐HCl indicated that there was a significant difference in the values of sedimentation coefficients.

The same conditions were applied to the measurements of viscosity; the difference was small but significant. These findings and the magnitude of the intrinsic viscosity suggested that this protein was in a disordered configuration. From these data, it is concluded that the protein was apparently monodispersed, in the presence or absence of the denaturing agent. This protein behaved like a polyelectrolyte in neutral aqueous solution.

The measurements of optical rotatory dispersion also confirmed that this protein existed in a disordered configuration.
SPECIFICITY AND KINETIC PROPERTIES OF MONOSACCHARIDE UPTAKE INTO GUINEA PIG CEREBRAL CORTEX IN VITRO
Authors: Bachelard H. S
Published: October 2006

Abstract— The uptake into the non‐raffinose space of cerebral cortex slices of a number of 14C‐labelled glucose analogues has been studied. Evidence on competition with glucose for the transport process has been used to derive information on the substrate specificity of sugar uptake to the brain. The kinetic properties of the uptake of 2‐deoxygIucose indicate that the transport is a facilitated process rather than diffusion. Classical competition between glucose and 2‐deoxyglucose for transport is shown and arguments are advanced for regarding glucose as a competitive inhibitor of 2‐deoxyglucose transport. The apparent Km for deoxyglucose is 10 mM and for glucose is suggested to be of the order of 5 mm, The value of such a kinetic approach to sugar transport in various conditions is discussed.
FATTY ACID COMPOSITION OF CEREBROSIDES, SULPHATIDES AND CERAMIDES IN MURINE SUDANOPHILIC LEUCODYSTROPHY: THE JIMPY MUTANT
Authors: Joseph K. C. , Hogan E. L.
Published: October 2006

The fatty acid composition of cerebrosides, sulphatides and ceramides was determined at 15‐16 days post partum in the brain of the Jimpy mutant and in littermate controls. There was a marked deficit in the long chain fatty acids (C22‐C24) of cerebrosides and sulphatides of Jimpy brain, with the unsubstituted fatty acids affected more than the alpha‐hydroxy fatty acids. A decrease of long chain normal fatty acids was also found in the ceramides of Jimpy brain. The deficit of long chain fatty acids in these sphingolipids of the Jimpy brain was more severe than that found in the Quaking mutant which has a less extensive disorder of myelin formation.
DISTRIBUTION OF TYROSINE HYDROXYLASE IN HUMAN AND ANIMAL BRAIN1
Authors: McGeer E. G. , McGeer P. L. , Wada J. A.
Published: October 2006

The activity of tyrosine hydroxylase (EC 1.10.3.1) when assayed under ideal conditions in young human brains, was comparable to that in brains of other species in level of activity and distribution. The highest levels of activity were in the putamen, caudate nucleus and substantia nigra, in keeping with data on other species. The caudate activity in human brain appeared to decrease substantially with increasing age. In both humans and baboons, the enzyme in the neostriatum was particle‐bound and inhibited by the 2‐amino‐4‐hydroxy‐6,7‐dimethyltetrahydropteridine cofactor system. In the substantia nigra it was soluble and stimulated by the 2‐amino‐4‐hydroxy‐6,7‐dimethyltetrahydropteridine cofactor system. The data suggest that tyrosine hydroxylase may be produced in a soluble form in the cell bodies of the substantia nigra but become bound as it moves toward the nerve endings in the putamen and caudate nucleus. The bound form of the enzyme was unstable but the soluble form exhibited considerable stability.
THE EFFECT OF PHOSPHOLIPASE C ON THE ACTIVITY OF ADENOSINE TRIPHOSPHATASE AND ACETYLCHOLINESTERASE IN SYNAPTIC MEMBRANES ISOLATED FROM THE CEREBRAL CORTEX OF SQUIRREL MONKEY1
Authors: Sun A. Y. , Sun G. Y. , Samorajski T.
Published: October 2006

A synaptic‐membrane fraction rich in junctional components and Na‐K ATPase and AChE activity was isolated from the cerebral cortex of the squirrel monkey. Incubation of membrane preparations with phospholipase C decreased the activity of Na‐K ATPase by 50 per cent but had no effect on the activity of AChE. Analysis of the membrane fraction showed that phospholipase C cleaved both choline phosphoglyceride and the diacyl type of ethanolamine phosphoglyceride from membrane lipids. Addition of egg lecithin at low concentrations partially restored the activity of Na‐K ATPase. Kinetic studies revealed that treatment with phospholipase C may produce a non‐competitive type of inhibition as a result of the cleavage of a charged phosphorylated nitrogen base from membrane lipids.
ACTIVATION OF PIG BRAIN GLUTAMINASE
Authors: Svenneby Gerd
Published: October 2006

Pig brain glutaminase (EC 3.5.1.2, l‐glutamine amidohydrolase) is activated by certain anions (e.g. phosphate, fluoride, carboxylic acids) and inhibited by others (e.g. chloride, bromide, iodide and glutamate). The only cation which has been found to activate the enzyme is the ammonium ion. This applies to both the tris‐HCl form and the phosphate‐borate form of glutaminase.
NOREPINEPHRINE INCREASES THE [32P]LABELLING OF A SPECIFIC PHOSPHOLIPID FRACTION OF POST‐SYNAPTIC PINEAL MEMBRANES
Authors: Berg G. R. , Klein D. C.
Published: October 2006

Abstract— Cultured pineal glands incorporated 32P into membrane phospholipids. Treatment of cultured glands with norepinephrine, which is known to stimulate membrane‐ bound pineal adenyl cyclase and to increase the production and secretion of melatonin, stimulated the incorporation of 32P into a phospholipid fraction of membranes and particulates containing phosphatidyl serine and phosphatidyl inositol. The labelling of other phospholipid fractions and the total 32P in the gland were not changed by norepinephrine treatment. Experiments with chronically‐denervated pineal glands indicated that the effect of norepinephrine on the [32P]labelling of phospholipids occurred at a postsynaptic site. When norepinephrine‐stimulated secretion of melatonin was partially inhibited by p‐chlorophenylalanine (a compound which blocks the synthesis of melatonin precursors), the norepinephrine‐stimulated labelling of phospholipids was still observed. Conversely, when melatonin secretion was stimulated in the absence of norepinephrine by treatment with the immediate precursor of melatonin, N‐acetylserotonin, a stimulation of 32P‐ labelling of phospholipids did not occur. These observations suggest that the increased [32P]‐ labelling of a phospholipid fraction caused by the norepinephrine treatment is not related to the secretion of melatonin. This effect on phospholipids may be associated with the interaction of norepinephrine with a membrane‐bound postsynaptic receptor. Stimulation by norepinephrine of [32P]‐incorporation into phospholipids has not been previously reported to occur in a tissue in which cholinergic fibres are absent.
THE STRUCTURAL SPECIFICITY OF THE HIGH AFFINITY UPTAKE OF l‐GLUTAMATE AND l‐ASPARTATE BY RAT BRAIN SLICES
Authors: Balcar V. J. , Johnston G.A. R.
Published: October 2006

Abstract— The high affinity uptake system for l‐glutamate and l‐aspartate in rat cerebral cortex may not be specific for these likely excitatory synaptic transmitters, as threo‐3‐hydroxy‐dl‐aspartate, l‐cysteinesulphinate, l‐cysteate and d‐aspartate strongly inhibit the observed high affinity uptake of l‐[3H]glutamate by rat brain slices in a manner consistent with linear competitive inhibition. These substances should therefore be considered as possible substrates for the transport system. Each of these four acidic amino acids excites central neurones in a manner similar to excitation induced by l‐glutamate, and as each might occur in brain tissue, their possible synaptic role should be investigated.

l‐Glutamate high affinity uptake was shown to be sodium‐dependent, but under certain conditions appeared to be less sensitive than GABA uptake to changes in the external sodium ion concentration, and to drugs which modify sodium ion movements. This may be relevant to the efficiency of the glutamate uptake process during synaptic depolarization induced by glutamate.

l‐Glutamate high affinity uptake was inhibited in a relatively nonspecific manner by a variety of drugs including mercurials and some electron transport inhibitors.
ISOLATION AND SOME CHEMICAL PROPERTIES OF OLIGODENDROGLIA FROM CALF BRAIN1
Authors: Poduslo Shirley E. , Norton W. T.
Published: October 2006

Abstract— The method of Norton and Poduslo (1970) for isolating brain cells has been adapted for the isolation of oligodendroglia from the white matter of calf brain. The cells were obtained in greater than 90 per cent purity, and in a yield of 11 × 106 cells/g of white matter. This number of cells represented a recovery of 11 per cent of the total cells in the tissue and therefore a considerably higher recovery of the original number of oligodendroglia. The average cell contained 5, 2 pg of DNA, 2–0 pg of RNA and 6, 7 pg of lipid. The lipid comprised cholesterol, galactolipid (both cerebroside and sulphatide) and phospholipid in the molar ratio of 1:0, 45:2, 3. Gangliosides were present in a concentration similar to that found in isolated rat neurons, The myelin‐specific enzyme, 2′, 3′‐cyclic nucleotide 3′‐phosphohydrolase, was present at a level nearly equal to that in myelin, and eight‐fold higher than the levels in rat neurons or astrocytes. The isolated oligodendroglia differed considerably from isolated astrocytes in size, morphology and chemical composition.
CEREBRAL CARBOHYDRATE METABOLISM DURING ACUTE HYPOXIA AND RECOVERY1
Authors: Duffy T. E. , Nelson S. R. , Lowry O. H.
Published: October 2006

Abstract— The levels of ATP, ADP, AMP and phosphocreatine, of four amino acids, and of 11 intermediates of carbohydrate metabolism in mouse brain were determined after: (1) various degrees of hypoxia; (2) hypoxia combined with anaesthesia; and (3) recovery from severe hypoxia. Glycogen decreased and lactate rose markedly in hypoxia, but levels of ATP and phosphocreatine were normal or near normal even when convulsions and respiratory collapse appeared imminent.

During 30 s of complete ischaemia (decapitation) the decline in cerebral ATP and phosphocreatine and the increase in AMP was less in mice previously rendered hypoxic than in control mice. From the changes we calculated that the metabolic rate had decreased by 15 per cent or more during 30 min of hypoxia.

Hypoxia was also associated with decreases of cerebral 6‐phosphogluconate and aspartate, and increases in alanine, γ‐aminobutyrate, α‐ketoglutarate, malate, pyruvate, and the lactate :pyruvate ratio. Following recovery in air (10 min), increases were observed in glucose (200 per cent), glucose‐6‐phosphate, phosphocreatine and citrate, and there was a fall in fructose‐1, 6‐diphosphale.

Similar measurements were made in samples from cerebral cortex, cerebellum, midbrain and medulla. Severe hypoxia produced significant increases in lactate and decreases in glycogen in all areas; γ‐aminobutyrate levels increased in cerebral cortex and brain stem, but not in cerebellum. No significant changes occurred in ATP and only in cerebral cortex was there a significant fall in phosphocreatine.

Phosphocreatine, ATP and glycogen were determined by quantitative histochemical methods in four areas of medulla oblongata, including the physiological respiratory centre of the ventromedial portion. After hypoxia, ATP was unchanged throughout and the changes (decreases) in phosphocreatine and glycogen were principally confined to dorsal medulla, notably the lateral zone.

Thus there is no evidence that respiratory failure is caused by a ‘power’ failure in the respiratory centre. It is suggested that in extremis a protective mechanism may cause neurons to cease firing before high‐energy phosphate stores have been exhausted.
QUICK FREEZING OF THE MURINE CNS: COMPARISON OF REGIONAL COOLING RATES AND METABOLITE LEVELS WHEN USING LIQUJD NITROGEN OR FREON‐121
Authors: Ferrendelli J. A. , Gay M. H. , Sedgwick W. G. , Chang M. M.
Published: October 2006

Abstract— Murine brains were frozen in situ, either in liquid N2 or in Freon‐12 cooled to its freezing point. The effect of these coolants on cooling rates and times in various CNS regions was determined. In addition, levels of ATP, P‐creatine and lactate were measured in selected regions of brains from both intact animals and severed heads frozen in either coolant. For both the intact animals and severed heads, superficial regions of brain cooled to 0°C and deeper regions to 25°C, at the same rate in either liquid N2 or Freon. Subsequent cooling was more rapid in liquid N2 in both regions. Levels of ATP, P‐creatine and lactate were similar in brains frozen in either coolant, probably because CNS utilization of highenergy phosphates decreased markedly as body temperature fell. In brains of animals frozen intact, levels of ATP and P‐creatine were higher and levels of lactate were lower than those in brains from heads which were severed prior to freezing. This difference may be a result of the marked stimulation which accompanies decapitation and may also reflect continued cerebral circulation in the intact animal for a brief time after immersing the animal in the coolant.
ACETYLCHOLINESTERASE DU MUSCLE, DE LA MOELLE EPINIERE ET DU CERVEAU DE GYMNOTE
Authors: Tsuji S. , Rieger F. , Peltre G. , Massoulie J. , Benda P.
Published: October 2006

Résumé— Dans le but d'étudier la localisation cytologique de I'AChE dans divers tissus de Gymnote, nous avons préparé un antisérum anti‐AChE en utilisant une préparation commerciale partiellement purifiée, contenant une forme globulaire de l'AChE Gp. Cet antisérum réagit dans le test de double diffusion avec l'enzyme purifiéGp, mais également avec la forme globulaire spontanée Gb, ainsi qu'avec les trois espèces ‘natives’ asymétriques A, C et D. Nous avons mis en évidence l'existence de ces quatres formes Gb, A, C et D dans des extraits de cerveau, de moelle épinière et de muscle de Gymnote. La forme globulaire Gb est particulièrement abondante dans la moelle épinière et à un moindre degré, dans le cerveau. La distribution des espèes est identique dans le muscle et l'organe électrique. Grâce à notre antisérum, nous avom Iocalisé par immunofluorescence indirecte l'AChE dans les terminaisons nerveuses sur le muscle, dans le cytoplasme de certains neurones situés dans le centre moteur de la décharge (moelle épinière) et au voisinage du noyau central de la décharge (cerveau).
ACTOMYOSIN‐LIKE PROTEIN IN BRAIN: SUBCELLULAR DISTRIBUTION
Authors: Puszkin S. , Nicklas W. J. , Berl S.
Published: October 2006

Abstract— An actomyosin‐like protein (neurostenin) has been isolated from the synaptosomal fraction of bovine and rat brains. A similar protein could not be obtained from the mitochondrial, microsomal, myelin or supernatant fractions. The synaptosomal protein is a Mg2+ ‐Ca2+ ‐stimulated ATPase which exhibited the phenomenon of superprecipitation and viscosimetric sensitivity to ATP characteristic of actomyosins. It constituted 8–10 per cent of the total synaptosomal proteins. The protein could be dissociated into actin‐like (neurin) and myosin‐like (stenin) proteins by ultracentrifugation in sucrose gradients containing KI and ATP. The neurin, as well as muscle actin, stimulated the Mg2+ ‐ATPase activity of stenin and muscle myosin; the relative viscosities of the mixtures were increased and became sensitive to added ATP. The neurin contained 0.9 mol of 3‐methylhistidine per 50,000 g of protein. The presence of these proteins in the synaptosomes suggests the possibility that they participate in nerve‐ending functions, e.g. release of transmitter materials.
EFFECTS OF METABOLIC INHIBITORS ON THE RELEASE OF GLUTAMATE FROM THE RETINA1
Authors: Harreveld A. Van , Fifkova Eva
Published: October 2006

—The superfused, isolated retina of the chicken was used to investigate the mechanisms responsible for the increase in retinal transparency and the release of glutamate associated with stimuli known to elicit spreading depression (SD). We sought to distinguish between (1) mechanisms involving glutamate‐induced increase in Na+ permeability and consequent uptake of extracellular material into the intracellular compartment and (2) mechanisms involving interference with operation of the Na+ pump that would result in a similar uptake of extracellular materials. Tetrodotoxin (which inhibits inward movements of Na+) depressed the transparency increase caused by stimulation with glutamate but not that elicited by application of KCl. Ouabain (which inhibits the Na+ pump) caused a marked increase in tissue transparency. The application of inhibitors of the aerobic metabolism, such as DNP or cyanide, or deprivation of O2 had no effect on the retinal transparency; results suggesting that the energy for the Na+ pump could be supplied by glycolysis. Indeed iodoacetate (which inhibits glycolysis) caused a marked change in transparency. Furthermore we found evidence for a compound in the superfusion fluid supplemented with iodoacetate that may be a reaction product of glutamate and iodoacetate. In some preparations superfusion with glucose‐free solutions caused a slowly developing increase in transparency and release of glutamate; in others the increase in transparency was more sudden and there was a larger release of glutamate. Seemingly, interference with the tissue metabolism can cause an uptake of extracellular material either by arrest of the Na+ pump or by the release of glutamate, depending on the conditions of the experiment.
Activation of phosphorylase kinase from brain by small amounts of calcium ion
Authors: Ozawa E.
Published: October 2006

Electrical stimulation of brain results in an enhancement of glycogen breakdown (King, Lowry, Passonneau and Venson, 1967) and one should therefore expect exitation to be linked in some way to glycogen metabolism. Stimulation of muscle cells, which induces contraction, also increases glycogen breakdown. In this case it has been shown that a minute amount of Ca2+, which couples excitation and contraction, also serves as a link between excitation and glycogenolysis (Ozawa, Hosoi and Ebashi, 1967). A small amount of Ca2+, released into the sarcoplasm as a result of excitation of the cell membrane, activates phosphorylase kinase. The activated kinase, in turn, converts phosphorylase α (the inactive form of phosphorylase) to phosphorylasea (the active form). The present communication summarizes the evidence that a similar mechanism operates in brain.
THE BIOCHEMICAL AND PHARMACOLOGICAL PROPERTIES OF 6‐AMINODOPAMINE: SIMILARITY WITH 6‐HYDROXYDOPAMINE
Authors: Heikkila R. E. , Mytilineou Catherine , Cote L. J. , Cohen G.
Published: October 2006

6‐aminodopamine was injected intraperitoneally into male Swiss–Webster mice. At 72 h post injection 6‐aminodopamine had caused a reduction in the endogenous content of heart norepinephrine, a decrease in the capacity of heart slices to accumulate [3H]‐norepinephrine in vitro, and a virtual disappearance of the adrenergic plexus of the mouse iris as viewed by fluorescence histochemistry. Similar data were obtained with the same dose of 6‐hydroxydopamine. These data suggest that 6‐aminodopamine causes a destruction of sympathetic nerve terminals. Model experiments showed that 6‐aminodopamine, like 6‐hydroxydopamine, generated H2o2both in vitro and in vivo. 6‐Aminodopamine, like 6‐hydroxydopamine, also blocked the accumulation of [3H]dopamine into slices of rat brain in vitro.
6‐AMINODOPAMINE‐INDUCED DEGENERATION OF CATECHOLAMINE NEURONS
Authors: Jonsson Gosta , Sachs Charlotte
Published: October 2006

the effects of 6‐aminodopamine on central and peripheral catecholamine neurons using fluorescence histochemical and isotope techniques have been investigated. Systematic administration of 6‐aminodopamine (20 mg/kg intraveneously) produced a rapid (within 1 h) and long‐lasting depletion of endogenous noradrenaline in adrenergic nerves of mouse atrium and iris with a concomitant loss of [3H]noradrenaline uptake. The effects were dosedependent. Accumulations of noradrenaline in non‐terminal axons were observed histochemically, indicating that 6‐aminodopamine induces neuronal damage. Desipramine completely blocked the 6‐aminodopamine induced noradrenaline depletion and reduction in [3H]noradrenaline uptake, indicating that 6‐aminodopamine has to be taken up by the axonal ‘membrane pump’ to produce its effects. Themonoamine oxidase inhibitor, nialamide, potentiated the effect of 6‐aminodopamine on [3H]noradrenaline uptake. 6‐Aminodopamine did not affect the cell bodies of the adrenergic neurons and there was a reappearance of adrenergic nerves and recovery of [3H]noradrenaline uptake. 6‐Aminodopamine does not seem to pass the blood‐brain barrier after systemic injection.

Intraventricular injection of 6‐aminodopamine in rats led to a considerable reduction in endogenous whole brain noradrenaline and [3H]noradrenaline uptake in slices from cerebral cortex and hypothalamus. Similar, but less pronounced effects were observed on dopamine neurons in the caudate nucleus. Histochemically, pronounced accumulations of transmitter were observed in the axons of the catecholamine neurons. The results obtained favour the view that 6‐aminodopamine is able to produce an acute and selective degeneration of catecholamine neurons similar to that seen after the neurotoxicagent, 6‐hydroxydopamine. Both compounds seemed to be approximately equally potent in their neurotoxicity, although 6‐aminodopamine seemed to be more generally toxic.
NEUROCHEMISTRY OF THE SPINAL CORD IN BRITISH SADDLEBACK PIGLETS AFFECTED WITH CONGENITAL TREMOR, TYPE A‐IV, A SECOND FORM OF HEREDITARY CEREBROSPINAL HYPOMYELINOGENESIS
Authors: Patterson D. S. P. , Sweasey D. , Brush Pamela J. , Harding J. D. J.
Published: October 2006

Congenital tremor, type A‐IV is an inherited abnormality of British Saddleback piglets characterized by the presence of poorly myelinated axons throughout the CNS. This is reflected by a general lowering of the spinal cord lipid content to about half control values. In particular, cerebroside and plasmalogen levels are markedly reduced.

Changes in the fatty acid composition of total lipid extracts and two isolated cerebroside fractions suggest that there is a metabolic defect in which fatty acid chain elongation, desaturation and hydroxylation are sub‐optimal.

Cholesterol esters accumulate, make up about 30 per cent of total sterols and contain more than 90 per cent of C16 and C18 fatty acids. These may have arisen through the breakdown of cerebrosides containing abnormal proportions of these acids. Slightly increased levels of acid hydrolase activity appear to confirm that abnormal or immature myelin is disposed of by enhanced macrophagic activity.

Differences between this and type A‐III, the sex‐linked inherited form of cerebrospinal hypomyelinogenesis are discussed and comparisons made with two forms of murine leuko‐dystrophy.
GAS CHROMATOGRAPHIC ESTIMATION OF ACETYLCHOLINE IN THE RABBIT HEART USING A NITROGEN SELECTIVE DETECTOR
Authors: Kilbinger H.
Published: October 2006

The distribution of ACh in the rabbit heart was investigated by a modified gas chromatographic estimation method. ACh was extracted with perchloric acid, precipitated as reineckate and demethylated with sodium benzenethiolate. The tertiary amines derived from ACh and other choline esters were concentrated by a microdistillation procedure. Gas chromatography was performed using a nitrogen selective detector. In the range of concentrations between 0.4 and 2.5 nmol ACh per tissue sample the coefficient of variation was 5.2 per cent. The recovery of ACh added to heart extracts was 101 per cent. Evidence for the identity of the choline ester isolated from rabbit hearts and authentic ACh was obtained by equal retention times and by correspondence of the ratio N/C of the respective tertiary amines. Parallel measurements using gas chromatography and bioassay on the rat blood pressure yielded closely corresponding values of ACh levels in the rabbit heart. The concentration of ACh was much higher in the atria than in the ventricles. In both atria, and ventricles the ACh concentration was higher in the right than in the left part of the rabbit heart. Endogenous propionylcholine or butyrylcholine were not detected.
BRAIN LEVELS AND TURNOVER RATES OF PRESUMPTIVE NEUROTRANSMITTERS AS INFLUENCED BY ADMINISTRATION AND WITHDRAWAL OF ETHANOL IN MICE1
Authors: Rawat A. K.
Published: October 2006

—Effects of acute or chronic administration of ethanol and its withdrawl on the steady‐state levels and turnover rates of certain neurotransmitters have been investigated in mice. The influence of long‐term administration of ethanol on the activities of enzymes involved in the metabolism of these transmitters has also been studied. Acute administration of ethanol or acetaldehyde or chronic administration of ethanol resulted in a decrease in the cerebral contents of acetylcholine, acetylCoA and CoA. Brain levels of 5‐hydroxytryptamine, norepinephrine and choline remained unchanged after acute administration of ethanol. However, chronic administration of ethanol resulted in a decrease in the norepinephrine content without significantly affecting 5‐hydroxytryptamine or choline contents. Cerebral levels of γ‐aminobutyric acid increased with both acute or chronic administration of ethanol. The total incorporation of [3H]choline into acetylcholine in brain was depressed upon acute administration of ethanol. After withdrawal of ethanol for one day cerebral levels of norepinephrine returned to normal; however, γ‐aminobutyric acid and acetylcholine returned to normal levels at 2 and 4 days after ethanol withdrawal, respectively. Pretreatment of mice with pyrazole, an inhibitor of alcohol dehydrogenase, prevented the ethanol‐induced decrease in cerebral acetylcholine levels. The activities of cerebral choline acetyltransferase and glutamic decarboxylase were decreased after 2 weeks of chronic ethanol administration. However, the activities of acetyl cholinesterase and GABA‐transaminase remained unaffected after 2 weeks of ethanol treatment
PREPARATION AND PROPERTIES OF A CELL‐FREE, HORMONALLY RESPONSIVE ADENYLATE CYCLASE FROM GUINEA PIG BRAIN1
Authors: Chasin M. , Mamrak F. , Samaniego Sylvia G.
Published: October 2006

—The accumulation of cyclic adenosine 3′,5′‐monophosphate (cyclic AMP) was studied in cell‐free homogenates of guinea pig brain. Homogenates, prepared in Krebs‐Ringer buffer, responded markedly to the addition of neurohormones with an increased rate of cyclic AMP synthesis; preparations from cerebellum, cerebral cortex, and hippocampus responded to a degree approximating that achieved with slices of these areas of guinea pig brain. Adenylatc cyclase activity was seen only when cyclic AMP was measured by a [3H]adenine prelabelling technique or when total cyclic AMP was measured by radioimmunoassay; [32P]ATP did not serve as a substrate for this preparation of the enzyme. The adenylate cyclase was paniculate and required a Krebs Ringer buffer; use of tris, or tris with Mg2+ and Ca2+, resulted in a preparation totally devoid of hormonal stimulation. Digestion by purified beef heart cyclic nucleotide phosphodiesterase, Dowex chromatography, solubility in Ba(OH)2‐ZnSO4 mixtures, and two thin layer chromatographic systems demonstrated that the product of the hormonally stimulated adenylate cyclase preparation was cyclic AMP. The selectivity of hormonal stimulation and the adrenergic character of the hormonal receptors from different brain areas were maintained in the cell‐free preparation. However, simultaneous stimulation with two different neurohormones resulted in additive responses, rather than in the potentiation observed in preparations of slices of brain.
PHOSPHOLIPID METABOLISM IN EXPERIMENTAL ALLERGIC ENCEPHALOMYELITIS: ACTIVITY OF MITOCHONDRIAL PHOSPHOLIPASE A2 OF RAT BRAIN TOWARDS SPECIFICALLY LABELLED 1,2‐DIACYL‐, 1‐ALK‐1′‐ENYL‐2‐ACYL‐ AND 1‐ALKYL‐2‐ACYL‐SN‐GLYCERO‐ 3‐PHOSPHORYLCHOLINE
Authors: Woelk H. , Kanig K. , Peiler‐Ichikawa K.
Published: October 2006

—1,2‐Diacyl‐, 1‐alk‐1′‐enyl‐2‐acyl‐and 1‐alkyl‐2‐acyl‐sn‐glycero‐3‐phosphorylcholine, specifically labelled with different fatty acids at the 2 position, were prepared enzymically using the acyltransferase system of rabbit sarcoplasmic reticulum. The substrates were submitted to hydrolysis by mitochondrial phospholipase A2 (phosphatide acyl‐hydrolase, EC 3.1.1.4) obtained from normal and from rat brain afflicted with EAE. In the acute stage of the disease an increase of approximately 25 per cent in phospholipase A 2 activity could be observed in comparison to that from the control animals for all investigated substrates. Phospholipase A2 obtained from normal rat brains and from those afflicted with EAE had a higher affinity for 1,2‐diacyl‐sn‐glycero‐3‐phosphorylcholine when compared to the corresponding alkyl acyl‐ and alkenyl acyl‐analogues. Choline plasmalogen was cleaved more slowly than the corresponding alkyl acyl derivative. The enzyme activity returned to the control level in the recovery stage of the demyelinating disease.
LABELLING OF ACETYLCHOLINE IN THE BRAIN OF MICE FED ON A DIET CONTAINING DEUTERIUM LABELLED CHOLINE: STUDIES UTILIZING GAS CHROMATOGRAPHY—MASS SPECTROMETRY
Authors: Hanin I. , Schuberth J.
Published: October 2006

—A method to achieve labelling of the acetylcholine stores of the brain under ideal physiological conditions is described. To this end, mice fed on a choline free diet were supplied with deuterium labelled choline in the drinking water. Labelled and unlabelled choline in plasma and in the brain as well as labelled and unlabelled acetyicholine in the brain were measured by a gas chromatographic‐mass spectrometric method. It was found that after 1–25 days on the deuterium choline diet, substantial amounts of the plasma choline and brain acetylcholine were displaced by deuterium choline and deuterium acetylcholine, respectively. Already on the first day, the mole ratio of deuterium choline/total choline in plasma was 0·22, and it approached a maximum of 0·57 on the 14th day. The mole ratios of deuterium acetylcholine/total acetylcholine in the brain were slightly but significantly lower than those of deuterium choline/total choline in plasma 1–14 days, but asymptotically approached the mole ratios of deuterium Ch/total Ch in plasma by 25 days. Intact brains submitted to incubation at room temperature for 10 min increased their total choline content by about 500 per cent. Concurrently, in brains from animals kept on a deuterium choline diet for 1–2 days, the level of deuterium choline rose only by 50 per cent after incubation. Deuterium choline levels increased, however, by 200–300 per cent in the brains from animals kept on the deuterium diet for longer time periods.

On the basis of these data it is suggested that: (a) choline in plasma is partly supplied from the food and partly from endogenous sources; (b) plasma choline rapidly equilibrates (less than one day) with a pool of Ch in the brain which is responsible for biosynthesis of acetylcholine; (c) the size of this choline pool is in the order of 34–40 nmol/g.
ALTERATIONS IN THE TURNOVER OF BRAIN NOREPINEPHRINE AND DOPAMINE IN ALCOHOL‐DEPENDENT RATS
Authors: Hunt W. A. , Majchrowicz E.
Published: October 2006

Abstract— The turnover of brain norepinephrine (NE) and dopamine (DA) was studied in five groups of male Sprague‐Dawley rats under different conditions of alcohol treatment: no treatment, acute treatment while intoxicated, acute treatment subsequent to elimination of alcohol from the blood, alcohol‐dependence while still intoxicated and alcohol‐dependence during a withdrawal syndrome. Turnover was determined from the rate of depletion of brain catecholamine levels after inhibition of tyrosine hydroxylase. In rats given a single dose of alcohol, NE turnover was increased, while DA turnover was unaffected during the few first hours after treatment. After that time the turnover of both NE and DA was reduced. In alcohol‐dependent rats, whether intoxicated or undergoing a withdrawal syndrome, the turnover of NE was increased, while that of DA was decreased. These data suggest that catecholamines may mediate some of the symptoms of the alcohol withdrawal syndrome in the rat.
IN VIVO RELEASE OF ENDOGENOUSLY SYNTHESIZED CATECHOLAMINES FROM THE CAT BRAIN EVOKED BY ELECTRICAL STIMULATION AND BY d‐AMPHETAMINE
Authors: Chiueh C. C. , Moore K. E.
Published: October 2006

Abstract— The cerebral ventricles of spinal‐sectioned cats were perfused with artificial cerebrospinal fluid after the intraventricular administration of [3H]DOPA or [3H]tyrosine. Endogenously synthesized [3H]dopamine or [3H]norepinephrine were identified in the perfusate. Electrical stimulation of catecholaminergic nerve tracts in the hypothalamus increased the efflux of both catecholamines. The addition of d‐amphetamine to the perfusing cerebrospinal fluid caused a large increase in [3H]dopamine and a small increase in [3H]norepinephrine appearing in the perfusate. Most of the endogenously synthesized [3H]catecholamines detected in the perfusate following stimuli originated from structures bordering the lateral cerebral ventricle. Thus, norepinephrine and dopamine can be synthesized in and released from catecholaminergic nerve terminals in structures bordering the cerebral ventricles.
DOPAMINE IN THE MESOLIMBIC SYSTEM OF THE RAT BRAIN: ENDOGENOUS LEVELS AND THE EFFECTS OF DRUGS ON THE UPTAKE MECHANISM AND STIMULATION OF ADENYLATE CYCLASE ACTIVITY
Authors: Horn A. S. , Cuello A. C. , Miller R. J.
Published: October 2006

Abstract— High concentrations of dopamine were found in the nucleus accumbens and olfactory tubercle of the rat brain using a radiochemical enzymatic assay technique. An active uptake system for [3H]dopamine that is temperature sensitive and dependent on external sodium ions is present in synaptosome‐rich homogenates of these two brain areas. This uptake process is potently inhibited by benztropine (IC50= 2.0 × 10‐7m). Dextroamphetamine d was 4.5 times more potent than 1‐amphetamine in inhibiting dopamine uptake in the nucleus accumbens and six times more potent in the olfactory tubercle and corpus striatum. Low concentrations of dopamine caused an increase in adenosine 3′5′‐monophosphate (cyclic AMP) formation in homogenates of both the nucleus accembens and olfactory tubercle. This effect was potently blocked by chlorpromazine. The α‐adrenoceptor antagonist phentolamine weakly antagonized the stimulation of this adenylate cyclase by dopamine, but the β‐adrenoceptor antagonist propranolol did not.