bluuebunny/crossref_metadata_2025 huggingface dataset:
REGIONAL RELEASE OF AROMATIC AMINES FROM TISSUES OF THE RAT BRAIN IN YITRO1
Authors: Baldessarini R. J. , Vogt Marcella
Published: October 2006

Abstract— Radioactive hydroxylated phenylethylamines were released in vitro by electrical stimulation of minces of brain tissues from several anatomically discrete areas, while labelled urea and amphetamine were poorly released from all regions. Release of [3H]norepinephrine occurred in the order hypothalamus > caudate nucleus ≥ cerebral cortex, thus in parallel with the distribution of endogenous norepinephrine. In contrast, [3H]tyramine was poorly released from cortical tissues but readily released from minces of caudate nucleus or hypothalamus. [3H]Octopamine was released from all areas, but was most readily released from thecaudatenucleus. Results for cerebral cortex were similar to those for coronal slices or minces of whole brain; release occurred in the order: norepinephrine > octopamine > tyramine in all three preparations. We suggest that certain β‐hydroxylated phenolic phenylethyl‐amines may be released from norepinephrine‐ or dopamine‐containing nerve endings in the brain, and that their non‐β‐hydroxylated congeners may be released from neurons in which endogenous amines are not β‐hydroxylated.
ASPARAGINASE IN PERIPHERAL NERVES OF THE GUINEA PIG IN WALLERIAN DEGENERATION AND EXPERIMENTAL ALLERGIC NEURITIS
Authors: Varsik P.
Published: October 2006

Abstract— Asparaginase (1‐asparagine amidohydrolase EC 3, 5.1.1.) activity in peripheral nerves in Wallerian degeneration and in experimental allergic neuritis was studied in the guinea pig. After mechanical damage to the sciatic nerve, asparaginase enzymic activity increased markedly in the regenerating (central) stump at the end of the first week, followed by a decrease in activity almost to control values in the course of 4 weeks, whereas in the degenerating (peripheral) stump, after an increase in activity at the end of the first week the enzyme activity continued to increase reaching 250 per cent of the control values at the end of the fourth week. An increase in asparaginase activity was also observed in experimental allergic neuritis.
ELECTROPHORETIC STUDIES OF BASIC PROTEINS CAPABLE OF INDUCING EXPERIMENTAL ALLERGIC NEURITIS
Authors: Kiyota K. , Egami S.
Published: October 2006

Abstract— A basic protein fraction capable of inducing experimental allergic neuritis was isolated from peripheral nervous tissues of ox and rabbit. The electrophoretic mobility was lower than that of lysozyme at pH 4, 2 and 8, 2. The yield was approximately 0, 1 g per cent of fresh tissue weight.
Levels of brain lipids in white matter from undernourished Sinclair (S‐1) miniature swine
Authors: Sun Grace Y. , Tumbleson M. E.
Published: October 2006

It Has been suggested previously that animal models are the preferred method for biochemical study concerned with protein‐calorie malnutrition (Kirsch, Saunders and Brock, 1968; Dobbing, 1970). That the brain is one of the least vulnerable organs to be affected by dietary deprivation has been reported for swine (Platt, Heard and Stewart, 1964; Tumbleson, Tinsley, Corwin, Flatt and Flynn, 1969; Tumbleson, Tinsley, Mulder and Flait, 1970), rhesus monkeys (Ordy, Samorajski and Hershberger, 1970) and rats (Brown and Guthrie, 1968). However, alteration of brain composition as a result of protein‐calorie malnutrition at a young age may have important effects on the mental and behavioural activities of the maturing subjects (Winick, 1970; Cravioto, 1970). In a previous study on the effect of undernutrition in young miniature swine, it was noted that there was an elevation in the levels of cholesterol and glucose in serum of pigs fed the low protein diet (Tumblesonet al., 1969). The duration of such elevations was usually 2–8 weeks after administration of the test diet. Since cholesterol, as well as other chemical constituents, in serum is important for the biosynthesis of brain membranes, the present study was designed to assess the effect of undernutrition on levels of major brain lipids.
SODIUM AND THE FLUX OF CALCIUM IONS IN ELECTRICALLY‐STIMULATED CEREBRAL TISSUE
Authors: Bull R. J. , Trevor A. J.
Published: October 2006

Abstract— The rate of efflux of 45Ca2+ from slices of rat cerebral cortex was resolved into two exponential curves which were attributed to an extracellular component and an intracellular or bound component. Electrical stimulation increased efflux of 45Ca2+ from the more stable pool and the time course for the redistribution of Na+ and K+ paralleled that for the increased efflux of Ca2+. This effect of stimulationwas dependent on the presence of Na+ in the incubation medium. Lack of Na+ in the medium during loading of the slices with 45Ca2+ increased uptake but on subsequent transfer to a medium containing Na+, electrical pulses failed to increase the rate of efflux of 45Ca2+. In unstimulated slices, the rate of efflux of 45Ca2+ was dependent upon the concentration ratio of Na+ to Ca2+ in the incubation medium. Saxitoxin and tetrodotoxin inhibited the increased efflux of 45Ca2+ that occurred during electrical stimulation but exerted no effect on Ca2+‐Ca2+ exchange. Our results suggest that there is a Na+‐dependent turnover of Ca2+ in brain slices which may involve changes in affinity at a common binding site. The possible involvement of such a Na+‐Ca2+ interaction in the regulation of neurotransmitter function is discussed.
CATION MODULATION OF SYNAPTOSOMAL RESPIRATION
Authors: Verity M. A.
Published: October 2006

Abstract— Synaptosomes were prepared from the cerebral cortex of the adult rat by a rapid technique, involving the use of centrifugation in a Ficoll‐sucrose discontinuous gradient. Adequate respiratory control ratios were obtained with glutamate and succinate plus rotenone. The addition of Na+ to the incubation medium stimulated synaptosomal, State‐4 respiration, with a half‐maximal response at 15 mM Na+. The stimulation by Na+ was inhibited by atractylate, oligomycin, ouabain or EDTA. A cooperative interaction between Na+ and low concentrations of Mg2+ was observed. A significant proportion (39 per cent) of the total Na‐K ATPase (EC 3.6.1.4) activity in the discontinuous gradient was localized in the synaptosomal fraction. In the absence of exogenous Mg2+, Na+ induced a 64 per cent stimulation of the synaptosomal ATPase activity which was sensitive to ouabain. Such stimulation of ATP hydrolysis would account for the formation of increased amounts of ADP, with consequent recycling to ATP through adequately controlled oxidative phosphorylation. These observations demonstrate a significant role for transmembrane cationic gradients in the control of synaptosomal respiration and mitochondrial oxidative phosphorylation. The preparation exhibits moderate respiratory control and should prove useful in studies of integrated mitochondrial oxidative metabolism and neuronal membrane function.
VARIATIONS IN AROMATIC AMINO ACID DECARBOXYLASE ACTIVITY TOWARDS DOPA AND 5‐HYDROXYTRYPTOPHAN CAUSED BY pH CHANGES AND DENATURATION
Authors: Bender D. A. , Coulson W. F.
Published: October 2006

—DOPA and 5‐hydroxytryptophan (5‐HTP) are generally supposed to be decarboxylated in mammalian tissues by a single enzyme, the two activities being present in constant ratio through a variety of purification procedures. It has now been shown that the ratio of activity of the liver enzyme towards the two substrates can be altered by mild treatments, such as might be used in solubilization of brain preparations. DOPA decarboxylase activity was preferentially inactivated by sodium dodecyl sulphate treatment, and 5‐HTP decarboxylation by urea.

Previous reports that the two substrates show different pH optima but are mutually competitive, have been confirmed. The Km of the enzyme towards 5‐HTP was lowest at pH 7.8 (the optimum pH for decarboxylation of this amino acid), but the variation with pH of the Km towards DOPA was unrelated to the pH optimum for decarboxylation. There appeared to be no relation between the probable ionization state of the substrates and the pH dependence of the enzyme. Studies on the binding characteristics of the enzyme for the two products, dopamine and serotonin, did not show any specific saturable binding.

It is proposed that the enzyme has a complex active site, with separate affinity sites for the two substrates, adjacent to a single catalytic site.
DIFFERENTIAL DETERMINATION OF HEXOSAMINIDASES A AND B AND OF TWO FORMS OF β‐GALACTOSIDASE, IN THE LAYERS OF THE HUMAN CEREBELLUM1
Authors: Hirsch Hilde E.
Published: October 2006

—In order to determine whether or not various histological elements of the nervous system may differ in their relative content of hexosaminidase A and B (O'Brien, Okada, Chen and Fillerup, 1970) and in the‘acid’and‘neutral’forms of β‐galactosidase (Ho and O'Brien, 1971), these isoenzymes were determined separately in the layers of human cerebellum. The proportion of the heat‐stable hexosaminidase B was greater in the granular layer than in the molecular layer or underlying white matter. The activity of the‘neutral’form of β‐galactosidase was very low compared to the‘acid’type, but its distribution was similar.
BRAIN PROTEINS: QUALITATIVE AND QUANTITATIVE CHANGES, SYNTHESIS AND DEGRADATION DURING FETAL DEVELOPMENT OF THE RABBIT
Authors: Cain D. F. , Ball E. D. , Dekaban A. S.
Published: October 2006

The composition and metabolism of the proteins of the cerebral pallium of the rabbit during the final one‐third of the gestational period were measured. During this period, the brain increased in size almost 10‐fold and the migration of neuroblasts to form the cerebral cortex became complete. Concurrent with the marked structural changes, the solubility characteristics and electrophoretic distribution of various brain proteins showed little change. However, at the time of birth and in the adult, significant differences in gel electrophoresis patterns were apparent. The rate of synthesis of protein in brain slices from the fetus of 20 days gestation was 3‐fold higher per mg of tissue than in the neonate and about 30‐fold higher than in the adult. Activities of acidic and neutral proteases per unit weight were virtually the same and nearly constant throughout the late fetal period. However, during this stage, while rapid growth persists, the total protein synthetic activity of the pallium predominated over the total proteolytic activity, whereas sometime after birth the ratios of these activities reversed consequent to a shutdown of the synthetic process.
HISTOCHEMISTRY OF MYELIN–XV. CHANGES IN THE MYELIN PROTEINS OF THE PERIPHERAL NERVE UNDERGOING WALLERIAN DEGENERATION–ELECTROPHORETIC AND MICRODENSITOMETRIC OBSERVATIONS
Authors: Adams C. W. M. , Csejtey J. , Hallpike J. F. , Bayliss O. B.
Published: October 2006

The chronological order of changes in rat peripheral nerve proteins during Wallerian degeneration has been investigated by microdensitometric and electrophoretic techniques. Both methods revealed an early loss of myelin proteins. The histochemical microdensitometric study showed a very substantial early loss of stainable protein basic groups and a somewhat slower progressive loss of the major protein component of peripheral nerve myelin (the J band). The electrophoretic study showed an early loss of both the J band protein and the slower‐moving basic protein band. The histochemical study also suggested that some cerebroside may be lost in the early stage of Wallerian degeneration. It is concluded that degradation of myelin proteins is an initial event in the process of myelin breakdown.
INCORPORATION OF PHENYLALANINE, TYROSINE AND TRYPTOPHAN INTO PROTEIN OF HOMOGENATES FROM DEVELOPING RAT BRAIN: KINETICS OF INCORPORATION AND RECIPROCAL INHIBITION
Authors: Oja S. S.
Published: October 2006

The kinetics of the incorporation into protein of [3H]phenylalanine, [3H]tyrosine and [3H]tryptophan were studied with homogenates prepared from whole brain of 1‐, 7‐, 21‐ and 60‐day‐old rats. The maximal velocities (Vmax)of incorporation of phenylalanine and tyrosine decreased and the apparent Michaelis‐constants (Km) for all three amino acids increased with increasing age of the rats. Tyrosine had the smallest and tryptophan the largest Km values in all age groups. Phenylalanine competitively inhibited the incorporation of tyrosine, but tyrosine inhibited non‐competitively the incorporation of phenylalanine. Tryptophan inhibited competitively the incorporation of phenylalanine, but at least partially non‐competitively the incorporation of tyrosine. Phenylalanine and tyrosine did not significantly affect the incorporation of tryptophan in homogenates from 60‐day‐old rats. In 1‐day‐old rats only a very large excess of phenylalanine or tyrosine inhibited detectably. The Ki for phenylalanine in the incorporation of tyrosine was significantly smaller in 1‐ than in 60‐day‐old rats. In every case the inhibition presumably occurred at a single rate‐limiting step in the complicated process of incorporation of amino acids into protein.
HYPOXANTHINE‐GUANINE‐PHOSPHORIBOSYL‐TRANSFERASE FROM RAT BRAIN (PURIFICATION, KINETIC PROPERTIES, DEVELOPMENT AND DISTRIBUTION)
Authors: Gutensohn W. , Guroff G.
Published: October 2006

Hypoxanthine‐guanine‐phosphoribosyltransferase (HGPR Tase; ECC 2.4.2.8) has been purified from rat brain 650‐fold to about 50 per cent purity by conventional methods. An isoenzyme pattern of at least three components is observed on DEAE‐cellulose chromatography. On polyacrylamide disc electrophoresis only one sharp band of enzyme activity can be detected. The apparent Km‐value determined for phosphoribosylpyrophosphate (PRPP) is about 0.2 mM. The product, GMP, and also GDP, GTP, UMP, CMP, AMP and ATP are competitive inhibitors with respect to PRPP. Inhibition by a number of other nucleotides has also been investigated. Studies on the development of enzyme activity in the brain of the young rat show that a rapid increase occurs during the first 15‐20 days of life and reaches a plateau thereafter. The regional distribution of HGPRTase activity in adult rat brain is more homogenous than that reported for human brain. The enzyme is predominantly a constituent of the soluble supernatant fraction, but can also be found in carefully washed synaptosomes. An antiserum against rat brain HGPRTase obtained from rabbits inhibits this enzyme to about 30 per cent of control activity, but does not crossreact with HGPRTases from rabbit or human erythrocytes.
RAPID AXONAL TRANSPORT IN VITRO IN THE SCIATIC SYSTEM OF THE FROG OF FUCOSE‐, GLUCOSAMINE‐ AND SULPHATE‐CONTAINING MATERIAL
Authors: Edstroum A. , Mattsson H.
Published: October 2006

—An in vitro system from the frog has been used to study fast axonal transport of glycoproteins. The migration of [3H]fucose‐, [3H]glucosamine‐ and [35S]sulphate‐labelled material was followed from the dorsal ganglia, along the sciatic nerve towards the gastrocnemius muscle.

The distribution in different subcellular fractions, effect of cycloheximide and transport kinetics did not differ very much between fucose‐ and glucosamine‐incorporation into the nerve. Cycloheximide blocked the synthesis of TCA‐insoluble radioactivity, which was transported at a rate of 60–90 mm per day at 18°C, more effectively than the synthesis of stationary proteins in the ganglia. About 10 per cent of the TCA‐insoluble and transported radioactivity was extracted by chloroform‐methanol (2:1, v/v) and might be glycolipids and the rest glycoproteins. Results suggest that TCA‐soluble activity, which was recovered in the nerve, originated in part from labelled macromolecules consumed along the axons. The rapidly transported TCA‐insoluble radioactivity was 85 per cent particulate and mainly associated with structures sedimenting in the microsomal fraction.

[35S]Sulphate‐labelled TCA‐insoluble material was resistant towards chloroform‐methanol (2:1, v/v) extraction and rapidly transported from the ganglia into the nerve. The synthesis was inhibited by cycloheximide. The material, probably proteoglycans, represented a quantitatively minor part of transported glycoproteins.
CONTROL OF AEROBIC GLYCOLYSIS IN GUINEA‐PIG CEREBRAL CORTEX SLICES
Authors: Takagaki G.
Published: October 2006

—The effect of glutamate on aerobic glycolysis in guinea‐pig cerebral cortex slices was analysed in comparison with that of high‐potassium. In contrast to the increased glycolysis in 50 mm‐potassium medium which was accompanied by increases of fructose diphosphate and triose phosphates in the slices, the addition of 5 mm‐d‐glutamate to the medium increased the rate of glycolysis without increasing these intermediates. When increasing the concentration of potassium in the medium up to 20 mm, the rate of aerobic glycolysis was not increased although fructose diphosphate and triose phosphates in the slices were increased. At this potassium concentration in the medium ATP in the slices was highest. At 30 mm‐potassium the rate of glycolysis was increased significantly, but fructose diphosphate and triose phosphates were decreased. ATP was lower at 30 mm‐ than at 20 mm‐potassium. By increasing potassium to 40 mm and above, the rate of glycolysis was further increased, and fructose diphosphate and triose phosphates were again increased. Between 5 and 20 mm‐potassium in the medium the increasing effect of glutamate on glycolysis was very pronounced. d‐Glutamate decreased the amounts of ATP, fructose diphosphate and triose phosphates at any concentration of potassium in the medium. When adding cyclic AMP and 5′AMP to the slices, fructose diphosphate and triose phosphates were increased, but the rate of glycolysis was not increased. On the basis of these observations mechanisms of the control over glycolysis in guinea‐pig cerebral cortex slices are discussed. It is suggested that the glycolysis is controlled by the changes in ATP concentration through their action on the glyceraldehyde 3‐phosphate dehydrogenase and phosphoglycerate kinase system. The changed patterns of the glycolytic intermediate profile in the slices when adding ATP to the medium are consistent with this suggestion. The addition of l‐phenylalanine to guinea‐pig cerebral cortex slices did not inhibit the rate of glycolysis, although it inhibited the activity of pyruvate kinase.
IDENTIFICATION OF A CALCIUM‐BINDING, BRAIN SPECIFIC PROTEIN IN THE AXOPLASM OF SQUID GIANT AXONS
Authors: Alemá S. , Calissano P. , Rusca G. , Giuditta A.
Published: October 2006

Abstract— An acidic protein has been isolated from the optic lobes of two cephalopods, Sepia officinalis and Loligo vulgaris. The protein has been obtained in pure form by fractionation with ammonium sulphate and chromatography on DEAE‐cellulose and Sephadex G 100. Its apparent molecular weight is 13,000–15,000. Glutamic and aspartic acids account for 35 per cent of the amino acid residues. The protein binds Ca2+ ions with an apparent dissociation constant of 2·5 × 10−5 M at physiological concentrations of KCI. Antibodies have been prepared against the protein purified from Sepia officinalis. By the micro‐complement fixation technique it has been shown that the protein is highly concentrated in the nervous system of cephalopods and that the amount in the axoplasm of squid giant axons is eight to nine‐fold higher than in the optic lobes of the same animal.
Increase of brain tryptophan and stimulation of serotonin synthesis by salicylate
Authors: Tagliamonte A. , Biggio G. , Vargiu L. , Gessa G. L.
Published: October 2006

Indirect evidence indicates that the rate‐limiting step in the synthesis of brain 5‐HT is the concentration of tryptophan in brain and not, as previously considered (Green and Sawyer, 1966), tryptophan hydroxylase. In fact this enzyme has a Km for its substrate much higher than the concentration of tryptophan normally present in the mammalian brain (Jequier, Lovenberg and Sjoerdsma, 1967; Jequier, Robinson, Lovesberg and Sjoerdsma, 1969; Mcgeer, Peters and Mcgeer, 1968). Tryptophan is the only amino acid circulating in plasma which is highly bound to serum proteins (Mcmenamy and Oncley, 1958). We have previously shown that the free fraction of serum tryptophan controls the concentration of brain tryptophan and, therefore, 5‐HT synthesis as well (Tagliamonte, Biggio and Gessa, 1971d; Gessa, Biggio and Tagliamonte, 1972). Salicylate has been shown to displace tryptophan from its protein binding in plasma and to raise the free tryptophan concentration (Mcarthur and Dawkins, 1969; Smith and Lakatos, 1971). These considerations prompted us to study the effect of salicylate on tryptophan concentrations and 5‐HT metabolism in brain.
COMPARATIVE STUDIES IN SYNAPTOSOME FORMATION: THE PREPARATION OF SYNAPTOSOMES FROM THE HEAD GANGLION OF THE SQUID, LOLIGO PEALII
Authors: Dowdall M. J. , Whittaker V. P.
Published: October 2006

Abstract— Relatively high concentrations of ACh have been found in the head ganglion of the squid (Loligo pealii) and the identity of the ACh has been verified by ion‐exchange chromatography. Following homogenization in media iso‐osmotic with sea water about 40 per cent of the ACh survives in particle‐bound form. Experiments using media of varying osmolarity suggest that this bound ACh is osmotically sensitive. A study has been made of the subcellular fractionation of squid head ganglion using sucrose homogenates. A rapid and novel method is described for the preparation of a synaptosome fraction freed from mitochondria. This preparation contains synaptosomes of well‐preserved morphology with occluded cytoplasm and a high specific content of ACh. The synaptosomes are osmotically sensitive and when suspended in water they burst, releasing cytoplasmic constituents and ACh‐containing synaptic vesicles. The synaptic vesicles can be separated from other sub‐synaptic constituents by density gradient centrifugation.
COMPOSITION OF MYELIN LIPIDS AND SYNTHESIS OF 3‐KETODIHYDROSPHINGOSINE IN THE VITAMIN B6‐DEFICIENT DEVELOPING RAT1
Authors: Kurtz D. J. , Kanfer J. N.
Published: October 2006

Abstract— Recoverable myelin in 20‐day‐old, Vitamin B6‐deficient rats was reduced from that in control animals. The composition of myelin lipids from deficient animals was nearly identical to that for controls except for a striking reduction in phospholipids polyunsaturated fatty acids. Enzymatic synthesis in vitro of 3‐ketodihydrosphingosine was impaired in the deficient animals; addition of the vitamin Bs cofactor to these incubation mixtures restored activity of the condensing enzyme to control levels.
THE UPTAKE OF PURINES BY RAT BRAIN IN VIVO AND IN VITRO
Authors: Nakagawa S. , Guroff G.
Published: October 2006

Abstract— The uptake of [14C]guanine and some of its [14C]‐labelled derivatives into rat brain was studied in vivo and in vitro. In vivo guanine, guanosine, and hypoxanthine penetrated the brain of adult rats to a very small extent. Inosine was taken up somewhat better. In young animals, also, guanosine was taken up poorly, but guanine was taken up fairly well. When guanine was administered to adult animals, only guanine was found in the brain. In young animals, by contrast, radioactivity from guanine appeared in guanosine and in guanine nucleotides, but no free guanine was found. In vitro guanine was taken up much better and, in fact, remained mostly as guanine in slices from 10‐day‐old rats. The in vitro conversion of guanine to GMP and its incorporation into RNA was unimpaired by the addition of unlabelled guanosine, an indication that guanine was converted directly to GMP. The uptake of guanine in vitro was not subject to competitive inhibition or influenced by the presence of dinitrophenol. This finding suggested that guanine entered the slice by simple diffusion.
THE MITOCHONDRIAL REDOX STATE OF RAT BRAIN
Authors: Miller A. L. , Hawkins R. A. , Veech R. L.
Published: October 2006

The use of the glutamate dehydrogenase (EC 1.4.1.3) and β‐hydroxybutyrate dehydrogenase (EC 1.1.1.30) reactions for the calculation of the mitochondrial redox state of brain has been examined. To prevent post‐mortem anoxic metabolism, brains were frozen in less than a second by using a new technique. Levels of ketone bodies in brain were so low relative to the contamination by blood and extracellular fluid that calculation of the mitochondrial redox state using the β‐hydroxybutyrate dehydrogenase reaction was not practical. The concentrations of the non‐nucleotide substrates of the glutamate dehydrogenase reaction could be accurately measured in brain and themitochondrial [NAD+]/[NADH] ratio calculated from the ratio [α‐oxoglutarate] [NH4+]/[glutamate]. The calculation is valid if the ratio [α‐oxoglutarate] [NH4+]/[glutamate] in mitochondria is the same as that measured in whole tissue. The evidence supporting this conclusion is the near‐equilibrium of the aspartate aminotransferase (EC 2.6.1.l) reaction in brain and the observation by others that the distribution of label between α‐oxoglutarate and glutamate in brain, after administration of labelled precursors, conforms to expectation. The alanine aminotransferase (EC 2.6.1.2) reaction was not near equilibrium in brain, probably because of the low in vivo activity of the enzyme.
LYSOLECITHIN AND SPHINGOSINEPHOSPHORYL‐CHOLINE IN THE METABOLISM OF BRAIN PHOSPHOLIPIDS OF THE RHESUS MONKEY (MACAC A MULATTA): EFFECTS OF DEVELOPMENT
Authors: Portman O. W. , Illingworth D. R. , Alexander M.
Published: October 2006

The rates of incorporation of palmitate from palmitoyl CoA into lecithin or sphingomyelin by homogenates of neural tissue of rhesus monkeys were greatly increased by the addition of lysolecithin or sphingosinephosphorylcholine (SPC). Labelled lysolecithin and SPC were also incorporated into lecithin and sphingomyelin. There was a low level of nonenzymic sphingomyelin formation from SPC and palmitoyl CoA. Choline from CDP‐choline was rapidly incorporated into lecithin and slowly into SPC and sphingomyelin by homogenates of pons. The activity of lysolecithin acyl hydrolase (EC 3.1.1.5) was high throughout life in homogenates of pons and cerebral cortex. The rate of utilization of palmitoyl CoA and lysolecithin for phospholipid synthesis was higher in neural tissue from fetal and neonatal monkeys than from adults. Lysolecithin was acylated most rapidly with palmitoleic, linoleic and arachidonic acids. All phospholipid metabolic activities were higher in the cerebral cortex than in the pons.
FEEDBACK REGULATION OF 5‐HT SYNTHESIS IN RAT STRIATAL SLICES
Authors: Hamon M. , Bourgoin S. , Glowinski J.
Published: October 2006

The effects of changes in intraneuronal levels of 5‐HT induced by monoamine oxidase inhibitors (MAOI) given in vivo or exogenous 5‐HT added in vitro on 5‐HT synthesis in striatal slices of the rat have been examined. The synthesis of 5‐HT was estimated by the measurement of the total formation of [3H]5‐HT and [3H]5‐hydroxyindole acetic acid from [3H]tryptophan and by calculation of the conversion index (CI) of tryptophan into 5‐HT. The small formation of [3H]tryptamine and [3H]indole acetic acid from [3H]tryptophan was taken into account in the estimation of 5‐HT synthesis. Both MAOI pretreament (180 min) and 5‐HT (2·8 μM) inhibited synthesis. The latter effect persisted in catecholamine depleted tissues and was related to intraneuronal changes in 5‐HT levels, since it could be prevented by chlorimipramine. The inhibition of 5‐HT synthesis was related to the decreased conversion of tryptophan into 5‐hydroxytryptophan and could not be prevented by p‐chloro‐phenylalanine pretreatment which depleted 5‐HT levels or by dibutyryl cyclic AMP which normally stimulated 5‐HT synthesis. Tryptophan uptake in slices was not affected by exogenous 5‐HT. The various mechanisms possibly involved in the end product regulation process of 5‐HT synthesis are discussed.
MONOAMINE OXIDASE (EC 1.4.3.4): ISOLATION AND CHARACTERIZATION OF MULTIPLE FORMS OF THE BRAIN ENZYME
Authors: Shih Jean Chen , Eiduson S.
Published: October 2006

Monoamine oxidase (MAO) in crude mitochondrial preparations from rat brain was solubilized, and different MAO‐active fractions were separated by agarose columns and by Sephadex electrophoresis. Any combination of these techniques yielded at least three fractions possessing MAO activity as measured by assays using radioactive serotonin and benzylamine as substrates. The molecular weight of one of the MAO forms was found to be approximately 400,000 daltons while another was at least 1.5 × 106 daltons. The crude mitochondria1 MAO was inhibited by [14C]‐labelled pargyline and then solubilized and the radioactivity of the soluble and particulate MAO was compared to the enzyme activity found in the soluble and particulate fractions. Our studies suggest that appreciable MAO activity is lost upon solubilization and that the conformation of MAO may be altered.
PHYSICO‐CHEMICAL CHARACTERISTICS AND REGIONAL DISTRIBUTION STUDIES OF GP‐350, A SOLUBLE SIALOGLYCOPROTEIN FROM BRAIN
Authors: Van Nieuw Amerongen A. , Roukema P. A.
Published: October 2006

The apparent molecular weight of GP‐350, a sialoglycoprotein from calf and rat brain, has been determined by SDS‐polyacrylamide gel electrophoresis. The electrophoretic mobility corresponds to the mobility of a polypeptide with a molecular weight of 11,600 ± 200. On this basis it can be calculated that only one sialic acid residue is present/GP‐350 molecule.

From isoelectric focusing experiments it appeared that the isoelectric point of GP‐350 is about 2. The determination of the amide content of the polypeptide chain showed that out of 22.0 acidic amino acid residues of glutamic acid and aspartic acid, only 4.9 residues are amidated. The total amount of the basic amino acid residues lysine and arginine, is 6.5. So, per molecule GP‐350 10.6 acidic amino acid residues are not counteracted by basic amino acid residues. The surplus of the acidic amino acid residues as well as sialic acid result in the pronounced acidic character of GP‐350. This fact is supported by the electrophoretic experiments.

The carbohydrate‐polypeptide linkage type has been studied by alkaline sodium borohydride treatment. Two thirds of all the galactosamine was destroyed, whereas the amount of glucosamine remained the same. Amino acid analysis indicated a decrease in serine and threonine with a concomitant small increase in alanine. These data point to the occurrence of linkages between the carbohydrate chain and the polypeptide core of the galactosamineserine or –threonine type. Per molecule GP‐350 about two residues of galactosamine are destroyed, indicating that two carbohydrate chains of this binding type are present. Only one of these chains can be terminated by a sialic acid residue. The other carbohydrate chain may be terminated by fucose.

Regional distribution studies showed the presence of GP‐350 in all brain areas studied; in relatively large amounts in the regions rich in ganglia such as caudate nucleus, cerebellar grey matter, pons and medulla oblongata, and in relatively small amounts in the regions poor in ganglia such as corpus callosum, cerebral white, cerebral grey and cerebellar white matter.

GP‐350 is also present in the pituitary gland. In the cerebrospinal fluid a glycoprotein is present with the same electrophoretic mobility as GP‐350. However, this glycoprotein gave no precipitin reaction with GP‐350 specific antiserum. Moreover, the amino acid composition was quite different from that of GP‐350.

Subcellular distribution study revealed that GP‐350 is present in the soluble cell fraction and in the synaptosomal membrane fraction, whereas it is absent from the purified nuclei, mitochondria, myelin, and also from the microsomal fraction.
SUBCELLULAR LOCALIZATION OF [14C]ADENINE DERIVATIVES NEWLY‐FORMED IN CEREBRAL TISSUES AND THE EFFECTS OF ELECTRICAL EXCITATION
Authors: Kuroda Y. , McIlwain H.
Published: October 2006

Abstract— Guinea pig neocortical tissues were incubated with [14C]adenine, dispersed in cold isotonic sucrose and subcellular fractions prepared by centrifugation. Some 98 per cent of the assimilated 14C was found as acid‐soluble nucleotides in the incubated tissues. In primary fractions obtained by differential centrifugation, about 60 per cent of the [14C]‐nucleotides were in supernatant fractions, in distinction to ATP of which the greatest molar quantity (61 per cent of that in the dispersion) was in the crude mitochondrial fraction. When the crude mitochondrial fraction was separated by density gradient centrifugation, most 14C was found in synaptosomal fractions and about 85 per cent of this 14C was adenine nucleotides.

Electrical stimulation of incubating tissues immediately prior to their dispersion and centrifugation greatly diminished the proportion of 14C subsequently found in nucleotides (collectively) in the supernatant fraction, and increased their inosine and hypoxanthine. Stimulation increased the tissue's cyclic AMP but a preferential localization for this was not established. Results are tentatively interpreted in terms of liberation of an adenine derivative on excitation, and its action or reuptake at a tissue component different from that from which it was liberated. Fractionation of tissues which had been incubated with both [14C]‐adenine and [3H]adenosine suggested that of the two compounds, more adenosine was taken up by synaptic regions in preference to other cellular regions of the tissue.
SEPARATION OF APPARENT MULTIPLE FORMS OF HUMAN BRAIN CHOLINE ACETYLTRANSFERASE BY ISOELECTRIC FOCUSING
Authors: White Helen L. , Wu Joyce Chen
Published: October 2006

Abstract— Choline acetyltransferase (acetyl‐CoA: choline O‐acetyl transferase; EC 2.3.1.6; ChAc) purified from human brain (basal ganglia) and sciatic nerve were separated into apparent multiple enzyme forms by the method of isoelectric focusing (pH gradient 3‐10) on acrylamide gel. A preparative separation of enzyme forms of human brain was accomplished by the column method, by using a sucrose gradient. When each separated form was re‐electrofocused, only a portion of the ChAc activity was observed in its original pH region while more than one‐half of the recovered activity for each fraction appeared at pH 7.8‐8. Gel filtration and kinetic studies of separated forms indicated that the more acidic forms might be aggregates, while more basic forms might be configurational isomers. Human ChAc of sciatic nerve did not exhibit acidic forms on electrofocusing, but otherwise yielded an electrofocusing profile similar to that of human brain. ChAc of rabbit brain and sciatic nerve each exhibited only a single form at pH 7.1 ± 0.2. Although ChAc differs among species, the enzyme of brain and sciatic nerve of the same species cannot be clearly distinguished by electrofocusing.
THE TURNOVER OF PHOSPHOGLYCERIDES IN THE SUBCELLULAR FRACTIONS OF MOUSE BRAIN: A STUDY USING [1‐14C]OLEIC ACID AS PRECURSOR1
Authors: Sun Grace Y.
Published: October 2006

Abstract— The turnover of phosphoglycerides in subcellular fractions of adult mouse brain was examined after intracerebral injection of [1‐14C]oleic acid. Radioactivity of the total brain homogenate decreased rapidly thereafter, with only 4 per cent of the radioactivity remaining at the end of 3 months. The rate of decrease of radioactivity in the subcellular fractions was in the order: cytosol, microsomes, synaptosomes and myelin. Increasing amounts of radioactivity were detected in the alkenyl groups and cerebrosides, but metabolic conversions were not as extensive as found previously with the palmitoyl group. The specific radioactivities for diacyl sn‐glycero‐3‐phosphorylcholine and diacyl sn‐glycero‐3‐phosphorylethanolamine were highest in the microsomal fraction and decreased with time. The apparent half‐lives for the diacyl sn‐glycero‐3‐phosphorylcholine and the diacyl sn‐glycero‐3‐phosphorylethanolamine in the microsome and synaptosome‐rich fractions were 1‐3.5 days when estimated between 1 and 7 days after injection. The rate of decay for the brain membrane phosphoglycerides was not linear with time, probably because of the extensive amount of recycling occurring within the system. Radioactivity was incorporated into the phosphoglycerides of the myelin but equilibration of radioactivity between microsomes and myelin required 7–14 days.
EFFECTS OF ALUMINUM SALTS ON CULTURED NEUROBLASTOMA CELLS
Authors: Miller Carol A. , Levine E. M.
Published: October 2006

Experimental induction of neurofibrillary tangles was demonstrated several years ago in the central nervous system of rabbits injected with aluminum salts. In the current studies, neuroblastoma cells, capable of morphologic and biochemical differentiation in monolayer culture, have been exposed to medium containing aluminum phosphate; such treatment resulted in an abundant accumulation of 100 Å neurofilaments after 6 days of continous exposure to the aluminum salt. While growth rates and incorporation of radioactive thymidine in treated cells remained similar to controls, total cellular protein, and incorporation of radioactive leucine were significantly increased. Paradoxically, when the protein content of aluminum‐treated cultures was maximal, these cultures contained about 20 per cent less ribosomal RNA per cell than in control cultures. In addition, activity of an important neuronal protein, i.e. acetylcholinesterase, was depressed in treated cultures to a level below control values. Both temporal and morphologic similarities between treated neuroblastoma cultures and animals injected with aluminum salts suggest that the observed changes in macromolecular synthesis in cell culture are relevant to in vivo studies.
DEVELOPMENTAL AND REGIONAL VARIATIONS IN NEUROTRANSMITTER‐SENSITIVE ADENYLATE CYCLASE SYSTEMS IN CELL‐FREE PREPARATIONS FROM RAT BRAIN
Authors: Hungen K. Von , Roberts S. , Hill Diane F.
Published: October 2006

Investigations have been carried out on regional and developmental variations in the properties of adenylate cyclase systems in participate preparations from rat brain. EGTA was routinely included in the assay medium to minimize differences in the state of activation of these systems resulting from variations in their exposure to endogenous Ca2+. At birth, adenylate cyclase activity was much higher in the hindbrain‐medullary preparations than in comparable fractions from cerebellum, cerebral cortex or subcortex (including midbrain, corpus striatum, hypothalamus and hippocampus). Adenylate cyclase activity increased during early development in preparations from all areas of the brain. Maximal levels were reached at 14 days of age or later. These levels were not greatly altered in the young adult animal, except in the hindbrain‐medullary area, where a decrease in activity was observed. Adenylate cyclase systems in cerebral cortical and subcortical preparations were activated by norepinephrine and dopamine throughout development. Serotonin also stimulated adenylate cyclase activity in these preparations from young animals but was much less effective in comparable fractions from adult rats. The response to dopamine was diminished with age in cerebral cortical preparations, but not in subcortical fractions. The responses to norepinephrine increased in both brain regions during early development. Adenylate cyclase systems in particulate preparations from the cerebellum and hindbrain‐medullary areas exhibited relatively poor responses to the biogenic amines. Detailed studies of the properties of the cerebral cortical adenylate cyclase systems revealed enhancement of activity by Ca2+ and F− at all stages of development with the maximal activation at 2–3 weeks of age. The results suggest that developmental differences in hormonal sensitivity of adenylate cyclase systems from diverse areas of the brain are related to changes in the proportions of the receptor‐enzyme complexes responsive to the different biogenic amines.
MEASUREMENTS OF RATES OF PROTEIN SYNTHESIS IN RAT BRAIN SLICES
Authors: Dunlop D. S. , Elden W. van , Lajtha A.
Published: October 2006

The use of tracer concentrations of labelled amino acids to measure incorporation in incubated slices of brain results in wide fluctuations with time in the specific activity of the precursor. Using concentrations of about 1 mm of labelled amino acid facilitates the accurate measurement of rates of synthesis. These higher precursor levels in the medium decrease the fluctuations in free amino acid specific activity due to dilution by endogenous amino acid and the production of amino acid by protein degradation, and decrease the lag in incorporation due to transport phenomena. Concentrations of 1 mm amino acid in the medium did not inhibit protein synthesis; with valine, leucine, phenylalanine, lysine and histidine, incorporation rates were similar when measured at trace concentrations and at 1 mm medium levels. The source of amino acid for protein synthesis appears to be intracellular. No evidence could be found for the preferential use of extracellular medium amino acid. The rate of incorporation of amino acids in incubated slices of rat brain was 0.087 per cent of the protein amino acid/h.
INHIBITION OF THE BIOSYNTHESIS OF ISOPRENOID COMPOUNDS BY PHENOLIC ACIDS IN THE RAT BRAIN
Authors: Ranganathan S. , Ramasarma T.
Published: October 2006

—The incorporation of [2‐14C]mevalonate into nonsaponifiable lipids by rat brain homogenates is inhibited by phenolic acids derived from tyrosine. The phenyl acids derived from phenylalanine are inhibitory only at very high concentrations compared with phenolic acids. The brain is more sensitive to inhibition by the phenolic acids than the liver. These studies indicate a possible role for phenolic acids in the impairment of cerebral sterol metabolism in phenylketonuria.
UPTAKE OF ACETYLCHOLINE AND CHOLINE INTO RAT BRAIN CORTICAL SLICES AND SYNAPTOSOMES AS RELATED TO 32Pi, INCORPORATION INTO THEIR PHOSPHOLIPIDS
Authors: Widlund L. , Heildronn E.
Published: October 2006

—The role of ACh‐stimulated 32Pi incorporation into the phospholipids of rat cerebral cortex slices and isolated nerve endings (synaptosomes) has been studied. ACh stimulation is not connected with any carrier‐mediated uptake of ACh. Such uptake may occur in slices in the presence of the anticholinesterase Sarin but barely in the presence of eserine. Regardless of the nature of the anticholinesterase used, rat cerebral cortex synaptosomes that respire and show high and low affinity choline uptake do not accumulate ACh against a concentration gradient. At exogenous ACh concentrations of 10–5m and above, some ACh enters the synaptosomes by diffusion and significantly stimulates 32Pi incorporation into phosphatidic acid. It is discussed whether, in isolated nerve endings, an increase in cytoplasmic ACh concentration due to diffusion may induce vesicle turnover to keep a balance between ‘free’ and bound ACh or if a presynaptic ACh receptor is responsible for the observed changes in phosphatidic acid. The distribution of accumulated radioactivity derived from exogenous choline and ACh respectively between ACh, choline, phosphorylcholine and betaine has been studied in slices and isolated nerve endings.
DEVELOPMENT OF LIPOGENESIS IN RAT BRAIN CORTEX: THE DIFFERENTIAL INCORPORATION OF GLUCOSE AND ACETATE INTO BRAIN LIPIDS IN VITRO
Authors: Patel M. S. , Tonkonow B. L.
Published: October 2006

—The oxidation to CO2 and the incorporation of [U‐14C]glucose and [U‐14C]acetate into lipids by cortex slices from rat brain during the postnatal period were investigated. The oxidation of [U‐14C]glucose was low in 2‐day‐old rat brain, and increased by about two‐fold during the 2nd and 3rd postnatal weeks. The oxidation of [U‐14C]acetate was increased markedly in the second postnatal week, but decreased to rates observed in 2‐day‐old rat brain at the time of weaning. Both labeled substrates were readily incorporated into non‐saponifiable lipids and fatty acids by brain slices from 2‐day‐old rat. Their rates of incorporation and the days on which maximum rates occurred were different, however, maximum incorporation of [U‐14C]glucose and [U‐14]acetate into lipid fractions being observed on about the 7th and 12th postanatal days, respectively. The metabolic compartmentation in the utilization of these substrates for lipogenesis is suggested. The activities of glucose‐6‐phosphate dehydrogenase, cytosolic NADP‐malate dehydrogenase, cytosolic NADP‐isocitrate dehydrogenase, ATP‐citrate lyase and acetyl CoA carboxylase were measured in rat brain during the postnatal period. All enzymes followed somewhat different courses of development; the activity of acetyl CoA carboxylase was, however, the lowest among other key enzymes in the biosynthetic pathway, and its developmental pattern paralleled closely the fatty acid synthesis from [U‐14C]glucose. It is suggested that acetyl CoA carboxylase is a rate‐limiting step in the synthesis de novo of fatty acids in developing rat brain.
PLASMA TRYPTOPHAN AND 5‐HT METABOLISM IN THE CNS OF THE NEWBORN RAT
Authors: Bourgoin S. , Faivre‐Bauman A. , Benda P. , Glowinski J. , Hamon M.
Published: October 2006

—The relationships between plasma tryptophan and 5‐HT metabolism in the CNS were studied in newborn rats and compared with adults. Both the concentration of free tryptophan in plasma and that of the amino‐acid in brain were much higher immediately after birth than later on. Drugs such as salicylate and chlordiazepoxide, which increased brain tryptophan concentrations in adults by displacing the plasma amino acid bound to serum albumin, were ineffective in newborn rats: most of the amino acid being already free in their plasma. The study of 5‐HT metabolism in brain stem slices revealed that the affinity of the uptake process for tryptophan was higher in newborn than in adult animals, whereas the reverse situation was observed for the enzyme complex involved in 5‐HT synthesis (lower apparent Km in adults). In addition, the catabolism of newly synthesized 5‐HT was more rapid in newborn than in adult tissues. Finally, the free state of tryptophan in plasma of newborn animals induced in brain both a high amino acid concentration and, in contrast to the situation observed in adults, a synthesis rate of 5‐HT very near its maximal value.
EFFECTS OF 5‐HYDROXYTRYPTOPHAN ON SEROTONIN IN NERVE ENDINGS1
Authors: McBride W. J. , Aprison M. H. , Hingtgen J. N.
Published: October 2006

—Preparations of synaptosomes (P2) from the telencephalon and from the diencephalon plus optic lobes of the pigeon and from the telencephalon of the rat were used to study the effects of 5‐hydroxytryptophan (5‐HTP) on (a) the levels of serotonin (5‐HT) in nerve endings and (b) the release of 5‐HT from nerve endings. The levels of 5‐HT were significantly higher (3.21 × 0.35 nmol/g original tissue weight) in the P2 fraction isolated from the telencephalon of pigeons given intramuscular injections of 50mg/kg of d,l‐5‐HTP in comparison to control values (1.42 ± 0.07). A similar twofold increase was observed with the P2 fraction isolated from the diencephalon plus optic lobes. In addition, the levels of 5‐HTP and 5‐hydroxyindoleacetic acid also increased significantly in these P2 fractions isolated from pigeons given d,l‐5‐HTP injections in comparison to values obtained for pigeons given saline injections. In vitro studies using preparations of synaptosomes (from both pigeon and rat) labelled with [3H]5‐HT indicated that 0.10 mil l‐5‐HTP increased the release of [3H]5‐HT twofold over control values. A concentration as low as 0.001 mm l‐5‐HTP was tested on the P2 fraction from the telencephalon of the pigeon and was found to significantly increase the release of [3H]5‐HT over control values. This effect by l‐5‐HTP was blocked if a decarboxylase inhibitor was added to the medium. l‐5‐HTP at a concentration of 1.5 mm had no apparent effect on the release of [3H]norepinephrine or [3H]dopamine from synaptosomes prepared from the telencephalon of the rat or pigeon. The results are discussed in terms of the role of serotonin in producing certain types of behavioral depressions exhibited by pigeons and rats given injections of 5‐HTP.