bluuebunny/crossref_metadata_2025 huggingface dataset:
ACTIVITIES OF 3,4‐DIHYDROXY‐l‐PHENYLALANINE AND 5‐HYDROXY‐l‐TRYPTOPHAN DECARBOXYLASES IN RAT BRAIN: ASSAY CHARACTERISTICS AND DISTRIBUTION
Authors: Sims K. L. , Davis G. A. , Bloom F. E.
Published: December 2006

Abstract— Optimal assay conditions for decarboxylation of 3,4‐dihydroxy‐l‐phenylalanine (DOPA) and 5‐hydroxy‐l‐tryptophan (5‐HTP) were determined in homogenates of rat brain by use of a sensitive, precise microradiometric technique. The two activities exhibited widely different optima for pH, temperature and substrate concentrations. The activity of 5‐HTP decarboxylase was stimulated 2‐fold by added pyridoxal‐5‐phosphate and was relatively resistant to antagonists of pyridoxal‐P. By contrast, the activity of DOPA decarboxylase was stimulated 20‐fold by added coenzyme and could be completely inhibited by carboxyl trapping agents. DOPA decarboxylase activity in subcellular fractions of brain was associated predominately with the soluble fractions and its distribution in the various fractions closely paralleled that of lactic acid dehydrogenase. 5‐HTP decarboxylase activity in brain was distributed almost equally between soluble and particulate fractions, and its distribution within the particulate fractions differed from that of succinic acid dehydrogenase. The two decarboxylases in brain exhibited a 7‐fold divergence in relative specific activity when their respective distributions in subcellular fractions were compared. Similarly, the regional distributions of the two decarboxylases in rat brain did not parallel one another; e.g. there was a 4‐fold difference between the ratio of the two activities in cerebellum and that found in the corpus striatum.
ACCELERATED POSTNATAL DEVELOPMENT OF d(‐)‐β‐ HYDROXYBUTYRATE DEHYDROGENASE (EC 1.1.1.30) ACTIVITY IN THE BRAIN IN HYPERTHYROIDISM
Authors: Grave G. D. , Satterthwaite S. , Kennedy C. , Sokoloff L.
Published: December 2006

Abstract— The activity of d(‐)‐β‐hydroxybutyrate dehydrogenase, a mitochondrial enzyme involved in ketone body metabolism, was found to be low in rat brain at birth, to rise. progressively to a peak during the first 3 weeks of postnatal life, and to decline after weaning to the low levels characteristic of the mature brain. Hyperthyroidism, induced from birth by administration of exogenous thyroxine, accelerated the postnatal development of the enzymic activity in brain and shifted the entire pattern of maturation to approximately 2 days earlier. The effects on the activity of the enzyme were the same with excessive doses of thyroxine which exaggerated the catabolic effects of the hormone and retarded brain and body growth or with lesser doses which had no apparent effects on brain and body growth or on the contents of nucleic acids and proteins in the brain. The accumulation of proteolipid protein in brain was also enhanced in hyperthyroidism. These results suggest that biochemical maturation of the brain is accelerated in hyperthyroidism.
GLYCOSIDASES IN NORMAL AND SCRAPIE MOUSE BRAIN
Authors: Millson G. C. , Bountiff Lynne
Published: December 2006

Abstract— The pH optima of ten glycosidases have been determined in normal and scrapie‐affected mouse brain. The enzymes α‐mannosidase, α‐glucosidase and β‐glucosidase displayed two peaks of enzyme activity over the pH range examined.

There is a significant increase in the activity of the enzymes α‐mannosidase, β‐glucuronidase, N‐acetyl β‐D‐glucosaminidase, N‐acetyl β‐galactosaminidase, β‐glucosidase (pH 4.1), α‐fucosidase and β‐xylosidase in the brains of mice clinically affected with scrapie, whilst only α‐mannosidase (pH 4.1), β‐glucuronidase, N‐acetyl‐β‐D‐glucosinidase and N‐acetyl‐β‐D‐gaiactosaminidase are elevated before mice exhibit signs of the disease.
THE ACCUMULATION OF RADIOACTIVE ACETYLCHOLINE BY A SYMPATHETIC GANGLION AND BY BRAIN: FAILURE TO LABEL ENDOGENOUS STORES
Authors: Katz H. S. , Salehmoghaddam S. , Collier B.
Published: December 2006

Abstract— The accumulation of radioactively labelled acetylcholine (ACh) by perfused superior cervical ganglia of cats and by incubated brain slices from rats was studied in the presence of diisopropylphosphorofluoridate. Ganglia accumulated more labelled ACh than an extracellular marker (inulin), but the amount of ACh accumulated did not increase when ACh turnover was increased by preganglionic nerve stimulation. The ACh that accumulated in ganglia was not released when the preganglionic nerve was subsequently stimulated. Sliced cerebral cortex also accumulated labelled ACh but this was not released when the tissue was subsequently exposed to a high K+ medium. Thus accumulated ACh does not appear to mix with releasable transmitter stores. Chronically (7 days) decentralized ganglia lost most of their transmitter store but retained their ability to accumulate labelled ACh. Uptake of ACh by sliced cerebellum was not less than uptake of ACh by sliced cerebral cortex and the amount of ACh accumulated by synaptosomes isolated from cerebellum was similar to the amount of ACh accumulated by synaptosomes isolated from cerebral cortex. It is concluded that ACh uptake is not specifically into cholinergic nerve endings. Hexamethonium reduced ACh uptake by cerebral cortex slices but did not increase the amount of ACh collected from slices stimulated by raised K+.
MULTIPLE DISC GEL BANDS OF MITOCHONDRIAL CREATINE AND ADENYLATE KINASES1
Authors: Lapin Evelyn , Maker H. S. , Lehrer G. M.
Published: December 2006

Abstract— The activities and electrophoretic patterns of creatine and adenylate kinases in the mitochondrial and high speed supernatant fractions of adult mouse brain were determined. Approximately 22 per cent of the activities of both kinases is firmly bound to the mitochondria. On acrylamide gel electrophoresis of creatine kinase, in addition to the major band previously described, there were several other bands found. Although present in both the mitochondrial and supernatant fractions these additional protein bands with creatine kinase activity were significantly more intense in the mitochondrial fraction. There was only onesecondary band of adenylate kinase activity in the mitochondrial fraction but additional bands were found in the soluble fraction.
CEREBRAL ANOXIA: EFFECT ON TRANSCRIPTION AND TRANSLATION1
Authors: Yanagihara T.
Published: December 2006

Abstract— The activity of DNA‐dependent RNA polymerase and the synthesis of microsomal protein were investigated after various periods of anoxic condition produced with rabbit brain in an in vitro experimental model. There was prompt inhibition of protein synthesis even after an anoxic period of 5 min, and inhibition was more than 80 per cent after an anoxic period of 30 min. However, RNA polymerase activity was retained during the early stage of anoxia, but definite inhibition appeared after an anoxic period of 15 min. Comparisons with other available information suggest that the inhibition of protein synthesis observed with brain slices is closely related to their polysomal function, that irreversibility of inhibition of protein synthesis might be related to the involvement of nuclear RNA synthesizing mechanism, and that these can occur both in the neuronal and glial elements.
STUDIES ON ACETYLCHOLINESTERASE OF RAT BRAIN SYNAPTOSOMAL PLASMA MEMBRANES
Authors: Goodkin P. , Howard B. D.
Published: December 2006

Abstract— A fluorimetric assay has been used to examine some kinetic properties of AChE from synaptosomal plasma membranes prepared from rat brain. The AChE bound to the plasma membranes was compared to that solubilized with Triton X‐100 and found to be essentially the same with respect to Michaelis constant and inhibitor constants for several AChE inhibitors. The two forms of the enzyme had slightly different pH optima. The kinetic studies revealed no evidence that synaptosomal plasma membrane AChE has allosteric properties. The solubilized enzyme was further purified by affinity chromatography.
PHOSPHOINOSITIDE METABOLISM IN RAT SUPERIOR CERVICAL GANGLION, VAGUS and PHRENIC NERVE: EFFECTS OF ELECTRICAL STIMULATION and VARIOUS BLOCKING AGENTS1
Authors: White G. L. , Schellhase H. U. , Hawthorne J. N.
Published: December 2006

Abstract— Paired vagus nerves, phrenic nerves or superior cervical ganglia from rats were incubated at 37 C for various times in a simple salt solution containing glucose and 32Pi. One of the pair was usually stimulated electrically for 30 or 60 min. Stimulation of vagus nerve for 30 min increased phosphate incorporation into all the phospholipids studied but the increase was significant only in the case of triphos‐phoinositide and diphosphoinositide. This increase was not accompanied by increased labelling of the nucleotide labile phosphate pool. Tetrodotoxin at concentrations sufficient to block transmission had no effect upon phospholipid labelling in vagus or phrenic nerve. Ouabain at blocking concentration did not affect polyphosphoinositide metabolism in vagus nerve but increased [32P]labelling of the other phospholipids. Hemicholinium‐3 increased the labelling of all three phosphoinositides in the sympathetic ganglia but the increase in phosphatidylinositol labelling due to electrical stimulation was not seen in the presence of this inhibitor.
ONTOGENETIC DEVELOPMENT OF A PHOSPHODIESTERASE ACTIVATOR AND THE MULTIPLE FORMS OF CYCLIC AMP PHOSPHODIESTERASE OF RAT BRAIN
Authors: Strada S. J. , Uzunov P. , Weiss B.
Published: December 2006

Abstract— The activity of cyclic AMP phosphodiesterase of rat cerebral homogenates increased several‐fold between 1 and 60 days of age. Enzyme activity in the cerebellum, on the other hand, did not increase during this period. A kinetic analysis of the phosphodiesterase activity revealed evidence for multiple forms of the enzyme and indicated that the postnatal increase in phosphodiesterase activity of rat cerebrum was due almost exclusively to the high Km enzyme. In cerebellum, the ratio of the high and low Km enzyme remained fairly constant during ontogenetic development.

Physical separation of the phosphodiesterases contained in 100,000 g soluble supernatant fractions of sonicated brain homogenates by polyacrylamide disc gel electrophoresis confirmed the presence of multiple enzyme forms. In adult rats we found six distinct peaks of phosphodiesterase activity (designated I to VI according to the order in which they were eluted from the column) in cerebellum and 4 forms of the enzyme (Peaks I through IV) in cerebrum. Brains of newborn rats had a different pattern and ratio of phosphodiesterase activities. For example, Peak I phosphodiesterase was undetectable in cerebrum or cerebellum of newborn rats. Moreover, in the cerebellum of newborn rats Peak II was the dominant peak whereas in the cerebellum of adult rats Peak III was the largest peak. A comparison of the multiple forms of phosphodiesterase from the cerebrum of newborn and adult animals suggested that the postnatal increase in phosphodiesterase activity previously seen in crude homogenates was due largely to an increase in a high K, Peak II phosphodiesterase. The ratios of activities of the other peaks and their sensitivities to an activator of phosphodiesterase were similar in newborn and adult rats.

An endogenous heat‐stable activator of phosphodiesterase was found in cerebrum, cerebellum and brain stem. In newborn rats, the cerebellum contained several‐fold less activity of this activator than did cerebrum or brain stem. However, the activity of this activator increased with age in the cerebellum and would appear to have decreased postnatally in cerebrum and brain stem.

These results suggest that some multiple forms of phosphodiesterase can develop independently and that changes in activities of these phosphodiesterases may occur by increases in the quantity of enzyme or by changes in the quantity of an endogenous activator of phosphodiesterase.
D‐GALACTOSE TRANSPORT BY SYNAPTOSOMES ISOLATED FROM RAT BRAIN
Authors: Warfield Anna S. , Segal S.
Published: December 2006

Abstract— Synaptosomes prepared by differential and Ficoll density gradient centrifugation took up d‐galactose by two saturable transport systems: one. a high affinity system with a Km of 0‐25 mn and Vmax of 075 nmol/mg protein 3 min, the other, a low affinity system with a Km of 47 mM and a Vmaxof 135 nmol/mg protein/3 min. The high affinity system was inhibited by 1‐5 mM phlorizin but was unaffected by the absence of sodium ion or the presence of 1 mM ouabain. The low affinity system was unaffected by phlorizin or ouabain. Both systems were inhibited by high concentrations of glucose. 2‐deoxyga‐lactose. and inositol, and by 2.4‐dinitrophcnol. Galactose was rapidly converted in synaptosomes to phos‐phorylatcd intermediates and was more slowly oxidized to 14CO2
SUBUNIT STRUCTURE AND KINETIC PROPERTIES OF 4‐AMINOBUTYRATE‐2‐KETOGLUTARATE TRANSAMINASE PURIFIED FROM MOUSE BRAIN
Authors: Schousboe A. , Wu J.‐Y. , Roberts E.
Published: December 2006

Abstract— The effects of divalent metal ions, sulfhydryl reagents, carbonyl trapping reagents, substrate analogs, and organic solvents on purified mouse brain 4‐aminobutyrate‐2‐ketoglutarate transaminase (EC 2.6.1.19) and the subunit structure of this enzyme were studied. Of the metal ions tested, Hg2+ was found to be the most potent inhibitor inhibiting the enzyme 50 percent at a concentration of 0‐7 μM. The order of decreasing inhibitory potency for the divalent metal ions was: Hg2+± Cd2+± Zn2+± Cu2+± Co2+± Ba2+± Sr2+± Ni2+± Mn2+± Ca2+± Mg2+. p‐Chloromercuribenzoale was the most potent inhibitor among the sulfhydryl reagents tested inhibiting the enzyme to the extent of 50 per cent at 0‐5 μM 3‐Mercaptopropionic acid was found to be a competitive inhibitor for GABA and non‐competitive for 2‐ketoglutarate. The Ki, value was estimated to be 13 μM. Aminooxyacetic acid was the most potent inhibitor of the carbonyl trapping agents with a K, value of 0‐06 μM. being competitive with GABA and non‐competitive with 2‐ketoglutarate. Hydroxylamine and hydrazine were the next most potent compounds in this group. Of a series of substrate analogs and metabolites tested, only acetic acid, propionic acid, butyric acid, glutamic acid, adipic acid, pimelic acid and 2‐ketoadipic acid inhibited the enzyme to a significant extent. Dioxan inhibited the enzyme 50 per cent at a concentration of 5 per cent (v/v) whereas methanol and ethanol only inhibited 5‐10 per cent at 10 per cent (v/v) concentration.

A spectrum of the native enzyme at pH 7‐2 showed maxima at 278 nm. 330 nm and 411 nm. Treatment of the enzyme with aminooxyacetic acid or 3‐mercaptopropionic acid caused the maximum at 411 nm to disappear.

Sodium dodecyl sulfate polyacrylamide gel electrophoresis of the enzyme revealed two protein bands. The molecular weights of these two subunits were determined to be 53.000 and 58,000, respectively.
NONHISTONE NUCLEAR PROTEINS OF RAT BRAIN
Authors: Fujitani H. , Holoubek V.
Published: December 2006

Abstract— The rat brain was dissected into cerebral cortex, cerebellum and the remaining regions. From the nuclei, isolated from these three brain sections, were extracted two fractions of nuclear sap proteins (proteins soluble in 014 M NaCl and proteins soluble in 01 M Tris‐HCl buffer pH 7‐6) and two fractions of nonhistone chromosomal proteins (one soluble in 0‐35 M NaCl and one which is not soluble at this salt concentration). Each of these four fractions of the nonhistone nuclear proteins was further separated by polyacrylamide gel electrophoresis. The electrophoretic patterns of the studied fractions of nuclear proteins are qualitatively identical regardless of the brain section from which the analysed protein fraction was isolated. In addition, there arc no qualitative differences in the electrophoretic patterns of nonhistone chromosomal proteins which are and which are not soluble in 0‐35 M NaCl. In contrast to the qualitative similarity of the electrophoretic patterns of proteins from different sections of the brain, the amount of the nonhistone nuclear proteins is characteristic for each studied brain section. The ratio of the total nonhistone nuclear proteins to DNA is highest in the brain cortex and lowest in the cerebellum. The most expressed difference between the nuclei is in the ratio of the nonhistone chromosomal proteins soluble in 0‐35 M NaCl to DNA. This ratio is 0‐52 in the cortex. 0‐38 in the mixture of noncortical and noncerebel‐lar regions and only 0‐18 in the cerebellum. The amount of the three fractions of nonhistone nuclear proteins in the nuclei of individual brain sections is proportional to the activity of the genome in these nuclei. The only exception are the nonhistone chromosomal proteins which are not soluble in 0‐35 M NaCl. These proteins and the histones are present in the same amounts in nuclei isolated from all three studied sections of the brain. The results support a proposal that the nonhistone nuclear proteins are involved in the expression of the genetic activity of the cell, without the majority of the proteins in any of the four fractions being the specific regulatory molecules.
CHANGES IN THE NEURONAL PROTEIN LABELLING INDUCED BY POTASSIUM IONS IN VIVO(SPREADING DEPRESSION)
Authors: KŘIVÁNEK J.
Published: December 2006

Abstract— Inhibition of incorporation of labelled leucine into the protein of the cerebral cortex induced by potassium ions in vivo (spreading depression) was analysed in isolated neuronal perikarya and compared with that in the whole cortex. Partition of proteins and amino acids and their radioactivities between tissue (cells) and incubation and disintegration media were checked at various steps of the separation procedure. The effect of potassium ions elicited in vivo persisted through all the steps of separation through to the neuronal perikarya pellets. The inhibition of amino acid incorporation was found to be less pronounced in perikarya than in the whole cortex. The validity of the separation method for the study of metabolic changes induced in vivo and possible participation of the glial cells in cerebral cortical responses to enhanced extracellular potassium are discussed.
EFFECTS OF DIFFERENT DIETARY LEVELS OF ESSENTIAL FATTY ACIDS ON THE FATTY ACID COMPOSITION OF ETHANOLAMINE PHOSPHOGLYCERIDES IN MYELIN AND SYNAPTOSOMAL PLASMA MEMBRANES
Authors: Karlsson I.
Published: December 2006

Abstract— Three dietary levels of essential fatty acids (EFA), 3 0, 0 75 and 0 07 calorie‐% were fed to rats for two generations or more. Myelin was isolated at the ages of 18, 30, 45 and 120 days and synaptosomal plasma membranes at 18, 30 and 45 days. No difference was found in the lipid composition between the dietary groups in either subcellular fraction. The fatty acid patterns of ethanolamine phosphoglycerides (EPG) were analysed. In myelin the proportions of 18:1 and 20:1 increased with age, while those of 20:4 (n‐6) and 22:6 (n‐3) decreased, in synaptosomal plasma membranes the proportions of 20:4 (n‐6) decreased with age, but 22:6 (n‐3) increased and the sum of the polyunsaturated fatty acids was constant. At no age were significant differences found between the proportions of saturated and monounsaturated fatty acids, in either myelin or the synaptosomal plasma membrane fraction, when the different dietary groups were compared. In myelin from rats fed 007 calorie‐% EFA the proportions of 20:4 (n‐6) were slightly lower than in the two other groups, while those of 22 6 (n‐3) were considerably lower. The synaptosomal plasma membranes fraction of rats fed O‐07 calorie‐% EFA had equal or slightly larger amounts of 20:4 (n‐6) than in the two other groups, while 22:6 (n‐3) was considerably smaller. In both subcellular fractions the decreased proportion of fatty acids of linoleic and linolenic acid series was compensated for by an increase in 20:3 (n‐9) and 22:3 (n‐9). The sum of these two fatty acids was equal in the EPG of myelin and synaptosomal plasma membranes at 18 days of age. At 30 and 45 days of age a lower value was found in the synaptosomal plasma membranes, while in the myelin fraction a slight decrease was found only at 120 days of age.
RNA‐DNA HYBRIDIZATION STUDIES WITH UNIQUE MOUSE DNA SEQUENCES1
Authors: Wintzerith M. , Mori K. , Mandel P.
Published: December 2006

Abstract— Unique mouse DNA sequences (not reassociated at cot 200) were prepared and hybridized with RNA fractions extracted at different temperatures with phenol from brain, liver and plasmocytoma cells. The hybridizations were carried out in liquid media, and the RNA‐DNA hybrids formed were separated on hydroxyapatite columns. The stringency of hybridization was measured by the sensitivity of the hybrids towards nuclease St, and by the Tm's of the RNA‐DNA hybrids.

A tissue specificity of RNA transcription has been found. Brain RNA's seemed to be more complex than those of liver. Brain RNA fraction I (primarily of cytoplasmic origin) hybridized to unique DNA sequences more efficiently than RNA fractions II + III (enriched in nuclear messenger RNA's) whereas the reverse was true for liver and plasmocytoma cell RNA.
POLYADENYLIC ACID‐CONTAINING RNA FROM RAT BRAIN SYNAPTOSOMES
Authors: DeLarco J. , Nakagawa S. , Abramowitz A. , Bromwell Katherine , Guroff G.
Published: December 2006

Abstract— Synaptosomal RNA of rat brain was labelled in vivo by intracranial injection of tritiated uridine. The change in the specific activity of this material with time was similar to that of polysomal RNA. The percent of the radioactive synaptosomal RNA which bound to oligo(dT)‐cellulose columns decreased with time after intracranial labelling. The percent of the total synaptosomal RNA which bound to oligo(dT)‐cellulose was greater than that of polysomes. The length of the polyadenylate (poly(A)) sequence of synaptosomal RNA was approximately one‐half that of polysomal RNA, and about the same as that from mitochondria. Investigation of synaptosomal RNA using sucrose gradients and polyacrylamide gel electrophoresis indicated that there were several distinct species present, and that they were similar to those from the mitochondria. The poly(A)‐containing RNA isolated from synaptosomes stimulated the incorporation of radioactive leucine into TCA‐precipitable material in a cell‐free protein synthesis system. Isolation of RNA from subsynaptosomal components indicated that most, if not all, of the synaptosomal messenger activity was localized in the synaptic mitochondria.
EFFECT OF AMANTADINE ON THE RATE OF DOPAMINE SYNTHESIS IN RAT CORPUS STRIATUM1
Authors: Bariletto S. , Dollar Elizabeth , Leitz F.
Published: December 2006

Abstract— The effect of amantadine on the rate of dopamine synthesis in rat corpus striatum was determined by three methods. (1) Measuring the rate of decline of endogenous dopamine following inhibition of synthesis with a‐methyltyrosine (α‐MT); (2) Measuring the rate of conversion of [3,5‐3H]tyrosine to 3H‐labelled catechols under conditions of an initial rate; and (3) measuring the levels of homovanillic acid (HVA), the principal metabolite of brain dopamine. Endogenous dopamine levels were 68‐1 n‐mole/g with a control synthesis rate of about 21 n‐mole/g/h as determined using either α‐MT or [3,5‐3H]tyrosine. Amantadine had no effect on synthesis at doses up to 100 mg/kg using α‐MT and [3,5‐3H]tyrosine. HVA levels were unaffected after 30 mg/kg drug, but were elevated 48%(P < 005) after 100 mg/kg of drug. By contrast apomorphine reduced and haloperidol increased synthesis as determined by all three methods. It is concluded that amantadine has no marked effect on dopamine synthesis in rat corpus striatum.
BIPHASIC MYELINATION AND THE FATTY ACID COMPOSITION OF CEREBROSIDES AND CHOLESTEROL ESTERS IN THE DEVELOPING CENTRAL NERVOUS SYSTEM OF THE DOMESTIC PIG
Authors: Sweasey D. , Patterson D. S. P. , GLANCY E. M.
Published: December 2006

Abstract— The chemical composition of four parts of the CNS (cerebrum, cerebellum, brain stem and spinal cord) was determined in 107 pigs at 11 stages of fetal and postnatal development and also in 6 adults. In cerebrum, cerebellum and brain stem, but not in spinal cord, the rate of increase in weight and the rates of change in lipid content slowed down for a period of about 10 days before and after birth. Cholesterol esters and desmosterol were only found in progressively decreasing amounts during the fetal stages of development and together with DNA these were exceptions to the general increases in the tissue concentrations and total amounts of other components during the period studied.

The onset of myelination, as measured by calculated daily increases in tissue contents of cerebroside took place between 70 and 80 days conceptual age and there were two peaks of activity, the first occurring 2 weeks before and the second 3 weeks after birth. Unlike the rate curve for total spinal cord weight the biphasic accumulation of DNA was not synchronous with myelin lipid accretion and the earlier prenatal DNA peak probably denotes proliferation of oligodendrocytes. The two phases of myelination are discussed in relation to an observed generalized pause in development immediately before and after birth.

Fatty acid analysis of cerebrosides indicated that, in spinal cord, chain elongation and desaturation are associated with myelination and continue with increasing activity until maturity. Consequently there was a progressive decrease in the proportion of saturated fatty acids. The fatty acid components of cholesterol esters in the developing pig were shown to be similar to those found during development in the CNS of other species but different from those found in demyelinating conditions.
CEREBRAL PROTEIN PATTERNS FROM TRAINED AND NAIVE PIGEONS
Authors: Barraco R. A. , Irwin L. N.
Published: December 2006

Abstract— Cerebral protein patterns resolved into 12 soluble fractions by ion exchange and 18 particulate fractions by gel electrophoresis were quantitatively analyzed from the cerebra of naive and trained pigeons. Behavioral treatment affected protein distribution significantly (P < 0.01) in 2 soluble and 2 particulate fractions, and marginally (P < 0.05) in a third fraction. The magnitude of the observed changes ranged from 12 to 57% of control values for a given fraction, but involved very small (< 1 mg/g brain) shifts in absolute protein concentration. These results support the view that protein patterns are basically stable to non‐traumatic behavioral stimulation, but that small changes in specific fractions can occur.
RAT BRAIN FOLATE IDENTIFICATION
Authors: Brody T. , Shin Y. S. , Stokstad E. L. R.
Published: December 2006

Abstract— Endogenous rat brain folates were identified using column chromatography for folate separation, authentic folate standards, and microbiological assay. The total folate content of rat brain was 360 ng per gram brain (wet wt) and consisted of tetrahydropteroylpentaglutamate (H4 PteGlu5, 29%), H4 PteGlu6 (14%), H4PteGlu7 (7%), 5‐CH3‐H4PteGlu4 (7%), 5‐CH3‐H4PteGlu5 (13%), and small amounts of formyl‐, methyl‐, and H4PteGlu1‐6 (~25%) and non‐methylated folates having a glutamate chain over seven glutamates long (4%). Overall folate oxidation state and one carbon forms were H4PteGlun (58%), 5‐CH3‐H4PteGlun (18%), 5‐ and 10‐CHO‐H4PteGlun (16%), and H2 PteGlun (8%). No PteGlun was detected.
CARBOXYLESTERASES WITH DIFFERENT SUBSTRATE SPECIFICITY IN HUMAN BRAIN EXTRACTS
Authors: Hojring Nina , Svensmark O.
Published: December 2006

Abstract— Methods for the determination of carboxylesterase activity in soluble as well as in particulate samples with p‐mtrophenylacetate and ‐butyrate and α‐naphthylacetate and ‐butyrate as substrates are described. Of the carboxylesterase activity of human brain, 8‐20% was present in aqueous extracts. Particle‐bound carboxylesterases could not be solubilized. By DEAE‐cellulose chromatography the carboxylesterases were separated into 6 more or less inhomogeneous fractions. One of these was further resolved into 2 fractions by chromatography on CM‐cellulose. Fractions obtained by ion exchange chromatography were resolved into several fractions by isoelectric focusing. Gel chromatography on Sephadex G‐200 resolved the carboxylesterases of brain extract into two fractions (molecular weights about 60.000 and 300,000). At least 4 different types of carboxylesterases could be distinguished on the basis of different substrate specificity.
CEREBRAL ANOXIA: EFFECT ON NEURON‐GLIA FRACTIONS AND POLYSOMAL PROTEIN SYNTHESIS
Authors: YANAGIHARA T.
Published: December 2006

Abstract— The incorporation of [3H]leucine into proteins of neuron‐enriched and glia‐enriched fractions was studied after various periods of anoxia produced in vitro in rabbit brain. Protein synthesis was carried out with brain slices, and the cellular fractions were subsequently separated with Ficoll density gradient ultracentrifugation. Leucine incorporation decreased promptly even at the early stage of cerebral anoxia (less than 10 min) and the incorporation in the glial fraction declined at least as much as the incorporation in the neuronal fraction. To substantiate that these changes were based on functional alteration of post‐transcriptional or translational mechanism at the polysomal level, polysomes were isolated from anoxic brain slices and polypeptide synthesis was carried out in vitro. The decrease of polypeptide synthesis correlated well with the decline of leucine incorporation in brain slices. Polypeptide synthesis decreased sharply between the 10‐min and the 20‐min anoxic period and a corresponding decrease of the polysomal peak was observed on the polysomal aggregation profile. This study indicated rapid and diffuse inhibition of protein synthesis in cerebral anoxia both in the neuronal and glial elements, the inhibition being based on the alteration of the mechanism for polypeptide synthesis at the polysomal level.
STUDIES ON THE INHIBITION OF BRAIN PHOSPHO‐FRUCTOKINASE BY OLEATE AND THE DETERMINATION OF FATTY ACIDS IN NORMAL AND HYPOXIC BRAIN
Authors: Broniszewska‐Ardelt B. , DA̧abrowiecki Z.
Published: December 2006

Abstract— Oleate inhibited phosphofructokinase activity in the brain in a way which was similar to known surface‐active protein denaturants. Experimental hypoxia produced an increase in the level of fatty acids in the microsomal, but not in the cytosol fraction of the brain. It is suggested that under hypoxic conditions the influence of fatty acids on the activity of phosphofructokinase (if any) is of non‐specific character.
ON THE RELEVANCE OF PREFERENTIAL INCREASES OF MESOLIMBIC VERSUS STRIATAL DOPAMINE TURNOVER FOR THE PREDICTION OF ANTIPSYCHOTIC ACTIVITY OF PSYCHOTROPIC DRUGS
Authors: Waldmeier P. C. , Maítre L.
Published: December 2006

Abstract— Drugs possessing (chlorpromazine, haloperidol, clozapine, thioridazine and sulpiride) or lacking (benzoctamine and perlapine) antipsychotic activity were compared with respect to their ability to enhance x‐methyl‐p‐tyrosine‐induced dopamine disappearance from the mesolimbic area and corpus striutum of rat brain. In addition, their effects on the endogenous concentrations of homovanillic (HVA) and 3.4‐dihydroxyphenylacetic (DOPAC) acids in these two brain areas were determined.

Some of the drugs enhanced dopamine disappearance in the mesolimbic area more than in the striatum. The most active in this respect were sulpiride. perlapine and chlorpromazine. By contrast, haloperidol was slightly more active in the striatum than in the mesolimbic area.

None of the drugs was more efficient in elevating HVA levels in the mesolimbic area than in the striatum. However, there were large differences in the relative extent of the HVA increases in the two regions. Benzoctamine, perlapine and chlorpromazine increased HVA concentrations in the mesolimbic area nearly as much as in the striatum. Thioridazine and haloperidol, however, elevated striatal HVA much more effectively.

Haloperidol and clozapine increased the DOPAC concentration in both areas to about the same extent. The other drugs were more active in the striatum. The largest difference between both regions was shown by chlorpromazine.

Perlapine and benzoctamine, both lacking antipsychotic activity, produced much larger increases of HVA than of DOPAC. This is in contrast to the results obtained with true neuroleptics and may reflect an involvement of release phenomena in the action of these two drugs on dopamine metabolism.

These results suggest that a preferential increase of dopamine turnover in the mesolimbic area is not necessarily linked to a better ratio of antipsychotic activity vs. extrapyramidal side effects. Moreover, an antiacetylcholine component of dopamine receptor blocking drugs does not seem to be a prerequisite for preferential activity on dopamine turnover in the mesolimbic system.
PURIFICATION OF PROTEIN CARBOXYMETHYLASE FROM OX BRAIN
Authors: Iqbal M. , Steenson T.
Published: December 2006

Abstract— The enzyme protein carboxymethylase from the soluble fraction of ox brain was purified to electrophoretic homogeneity. Brain protein carboxymethylase activity was also detected in a membrane‐bound form which could only be solubilized by treatment with detergent. The solubilized membrane‐bound form differed from the ‘native’ soluble form in that the former irreversibly lost activity on removal of the detergent. The two forms, however, have several similarities, having a molecular weight of 35,000, a Km of 2.7 × 10−6 M for S‐adenosyl‐L‐methionine, and a pH optimum of 6.2 when ovalbumin was used as the methyl acceptor.
EFFECTS OF PSYCHOTROPIC DRUGS ON NEUROTUBULE ASSEMBLY
Authors: Poffenbarger M. , Fuller G. M.
Published: December 2006

Abstract— The interaction of psychotropic drugs with brain microtubules was assessed by viscometry, [3H]colchicine binding studies and neurite growth in neuroblastoma cells in tissue culture. Of the thirteen drug‐ tested, only d‐amphetamine, chlorpromazine and reserpine inhibited the in vitro repoly‐merization of microtubules. However, the maximal drug effects observed in these studies occurred at concentrations in excess of the pharmacologically theraputic range. These results suggest: (1) the affinity of these drugs for tubulin appears to be similar to, but clearly less than, that observed for colchicine; (2) the toxic side effects of these drugs may be mediated, in part, by the microtubule system; (3) these drugs may inhibit microtubule assembly by disrupting secondary processes rather than by a direct interaction with tubulin.
EFFECT OF NGF AND DEXAMETHASONE ON PHENYL‐ETHANOLAMINE‐N‐METHYL TRANSFERASE (PNMT) ACTIVITY IN NEONATAL RAT SUPERIOR CERVICAL GANGLIA
Authors: Liuzzi. A. , Foppen F. H. , Saavfdra J. M. , Jacobowitz D. , Kopin I. J.
Published: December 2006

Abstract— Nerve‐growth factor (NGF) or dexamethasone administered to newborn rats result in increased levels of phenylethanolamine‐N‐methyl transferase (PNMT) activity in the superior cervical ganglia. Treatment with dexamethasone, but not NGF, also results in increased levels of epinephrine which parallel the increased PNMT in the ganglia. Dexamethasone slows the decrease in PNMT levels after cessation of NGF treatment, suggesting that dexamethasone decreases the rate of PNMT destruction. Examination of the ganglia by histofluorescence indicates that NGF increases the bundles of fibres while dexamethasone increases the number of small intensely fluorescent cells.
IN VIVO RNA SYNTHESIS WITHIN THE RAT NODOSE GANGLIA
Authors: Gunning P. W. , Kaye P. L. , Austin L.
Published: December 2006

Abstract— The in vivo synthesis of RNA in the rat nodose ganglia has been studied following the intravenous introduction of ortho‐[32P]phosphate. Analysis of the labelled RNA upon 2.2% polyacrylamide gels was performed. Rapidly‐labelled heterodisperse RNA. with a size range of 10S‐30S was detected after 3 h exposure to the isotope. Two peaks, of size 28S and 12S‐14S. were also observed. The former is thought to be processed 28S rRNA whereas the latter is consistent with its designation as ‘message‐like’ RNA (mlRNA). A rapidly turning‐over phosphorylated non‐nucleic acid contaminant prevented clear interpretation of the 4S region of the gel at short labelling times. However, this material was not present when the exposure time was increased to 24 h. At this time, only the stable RNA species 28S and 18S rRNA and 4S tRNA, were detected.
DIFFERENTIAL EFFECTS OF THREE DOPAMINE AGONISTS: APOMORPHINE, BROMOCRIPTINE AND LERGOTRILE
Authors: Silbergeld Ellen K. , Pfeiffer R. F.
Published: December 2006

Abstract— The ergolines are a new class of proposed dopamine receptor agonists, whose efficacy in treatment of Parkinsonism is under investigation. In order to explore the mechanisms of their action. two ergolines (bromocriptine and lergotrile) were compared to apomorphine for in vivo effects on behavior and in vitro effects on uptake and release of [3H]dopamine by brain minces. Inhibition of dopamine synthesis in vivo significantly interfered with both bromocriptine‐ and lergotrile‐induced stereotypy, while apomorphine‐induced stereotypy was not affected. Significant differences among the compounds were also seen neurochemically: bromocriptine inhibited the release of [3H]dopamine. while lergotrile increased release. Apomorphine did not affect uptake or release of [3H]dopamine. The results, of both behavioral and neurochemical experiments, suggest that two ergolines enhance dopaminergic function by action on presynaptic dopaminergic sites in addition to receptor agonism.
THE EFFECT OF EXTRACELLULAR POTASSIUM CONCENTRATION ON PROTEIN SYNTHESIS IN GUINEA‐PIG HIPPOCAMPAL SLICES1,2
Authors: Lipton P. , Heimbach Catherine J.
Published: December 2006

Abstract— We have measured the effect of small variations in extracellular potassium concentrations ([K+]) upon the incorporation of radioactively labelled amino acid into the protein of the isolated guinea‐pig hippocampal slice. The slice is super‐perfused with glucose fortified buffer and maintains an ATP concentration of 33–36 nmol/mg protein and incorporates lysine into protein at a rate of 0.82 pmol/(ig protein/h. Within the range of extracellular K+ from 1.3 to 8.1 mil the change in the rate of lysine incorporation into protein is proportional to the logarithm of the extracellular K+ concentration. Incorporation increases by about 100% over this range. Measurements of the specific activity of the presumed intracellular amino acid pool indicate that the effect of changes in extracellular [K+] is to alter the rate of protein synthesis rather than alter the availability of radioactively labelled precursor. Altering extracellular [K+] does not affect tissue levels of ATP or creatine phosphate, indicating that the effect on amino acid incorporation does not result from an effect upon energy metabolism. It is suggested that this effect of extracellular [K.+] may be a means by which changes in cerebral electrical activity lead to changes in the rate of protein synthesis in brain.
REGULATION OF ACETYLCHOLINE SYNTHESIS: CONTROL OF CHOLINE TRANSPORT AND ACETYLATION IN SYNAPTOSOMES
Authors: Jope R. S. , Weiler M. H. , Jenden D. J.
Published: December 2006

Abstract— The high affinity transport of choline (Ch) and the synthesis of acetylcholine (ACh) were measured in synaptosomes by measuring the utilization of [2H4]Ch. The synthesis of ACh was reduced under several conditions which reduce the availability of acetyl coenzyme A (AcCoA) including no glucose added, replacement of glucose with succinate or impairment of glucose utilization by bromopyr‐uvate, NaCN, or pentobarbital. These conditions did not reduce the amount of unacetylated [2H4]Ch in the synaptosomes indicating that the high affinity transport of Ch is not directly coupled to the synthesis of ACh.
AMINO ACID METABOLISM IN GLIAL CELLS: HOMEOSTATIC REGULATION OF INTRA‐ and EXTRACELLULAR MILIEU BY C‐6 GLIOMA CELLS
Authors: Nicklas William J. , Browning Edward T.
Published: December 2006

Abstract— The amino acid and carbohydrate metabolism of confluent cultures of C‐6 glioma cells has been investigated. It was observed that the presence of glutamine in the incubation fluid was essential to maintain high glutamine levels in the cells during a 2 h incubation. When cells were incubated in a cerebrospinal fluid‐like medium glutamate, glutamine, aspartate and γ‐aminobutyrate (GABA) levels were comparable to those occurring in whole forebrain of adult rat in vivo. Glucose uptake was high, approx 1 μmol/mg protein/2 h, 50% of which was accounted for by lactate production. Of the remaining glucose uptake a substantial proportion was unaccounted for by known oxygen‐coupled citric acid cycle flux, or glycogen or amino acid synthesis. Interestingly, the cells released into the medium significant amounts of the neuroinhibitory amino acids, GABA and glycine, and rapidly cleared the medium of the neuroexcitatory amino acids glutamate and aspartate. Metabolism of [2‐14C]glucose and [3H]acetate by the cells indicated rapid labelling of the glutamate and aspartate pools of the cells by glucose in 1 h, but the relative specific activities of glutamine and GABA were much lower. The metabolism of tracer concentrations of [3H]acetate to glutamate by the cells indicated greater dilution of this isotope compared to that of labelled glucose. However, the ratio of 3H to 14C radioactivity in glutamate and other amino acids was similar to that in the mixture of glucose and acetate added to the medium. Therefore, some active route of acetate metabolism which communicates metabolically with the route of glucose metabolism to glutamate appears to exist in the cells. Significant acetate activation and fatty acid turnover would explain the present results. Some of the amino acid labelling patterns observed in these studies are not consistent with these glial‐like cells behaving as models for the small compartment of amino acid metabolism in brain. Enzyme measurements corroborated the metabolic studies. Glutamate decarboxylase activity was 3–10% of the level found in whole brain. GABA transaminase was also low compared to brain as was glutamine synthetase. Glutamate dehydrogenase was present at levels equal to or higher than those of whole brain.
OCTOPAMINE: A HIGH‐AFFINITY UPTAKE MECHANISM IN THE NERVOUS SYSTEM OF THE COCKROACH
Authors: Evans P. D.
Published: December 2006

Abstract— In the CNS of the cockroach, Periplaneta americana, the uptake of the biogenic amine, octopamine, can be divided into three components. High and low affinity Na+‐sensitive components (Km's 0.5 μ and 19.8 UM respectively) are present, together with a Na+‐insensitive component which shows no saturation kinetics between 0.07 and 100 μ The structure‐specificity dependence of the components and their drug sensitivity have been examined. The significance of the high‐affinity uptake component is discussed in terms of amine inactivation, and its parallels with noradrenaline uptake in the vertebrate nervous system are considered.
THE GAUCHER MOUSE: DIFFERENTIAL ACTION OF CONDURITOL B EPOXIDE AND REVERSIBILITY OF ITS EFFECTS
Authors: Stephens M. C. , Bernatsky A. , Burachinsky V. , Legler G. , Kanfer J. N.
Published: December 2006

Abstract— Conduritol B epoxide is an inhibitor of non‐mammalian and mammalian β‐glucosidase. When injected in mice it produces the biochemical and certain clinical and pathological characteristics of Gaucher disease. An evaluation of the amount required to produce the Gaucher mouse revealed that (1) daily administration of the inhibitor was necessary and (2) lower doses were required to produce accumulation of glucosylceramide in brain than in liver or spleen. It is also demonstrated that reversibility of the effect of conduritol B epoxide can be achieved after it has been injected for a period of 3–4 weeks.
EFFECTS OF HISTIDINE ON THE TRANSPORT OF L‐DOPA BY SLICES OF BRAIN CORTEX AND STRIATUM OF THE RAT
Authors: Herreros B. , Garcia‐Sancho J. , Barbosa E.
Published: December 2006

Abstract—L‐Histidine inhibits the uptake of L‐DOPA by brain cortex or striatum slices in short‐term experiments, but increases it in long‐term experiments. The potentiation of the steady‐state accumulation of L‐DOPA by histidine is a result of thecis‐andtrans‐effects of histidine on the transport of L‐DOPA at both sides of the cell membrane. The results demonstrate the importance of hetero‐exchange phenomena in determining the cellular level attained for a given amino acid at the steady‐state.
BIOSYNTHESIS OF PROSTAGLANDIN E BY RAT SUPERIOR CERVICAL GANGLIA1
Authors: Webb J. G. , Saelens D. A. , Halushka P. V.
Published: December 2006

Abstract— —The biosynthesis of immunoreactive prostaglandin E (iPGE) was examined in homogenates of rat superior cervical ganglia and in isolated intact ganglia incubated in vitro. Ganglia homogenates produced iPGE from exogenous arachidonic acid. Prostaglandin synthesis by the homogenates was inhibited by the prostaglandin synthetase inhibitors, eicosatetraynoic acid, indomethacin and sodium meclofenamate and was stimulated by norepinephrine and dopamine. Whole ganglia incubated in Krebs‐bicarbonate solution also synthesized iPGE which was released into the incubation bath in a time‐dependent manner. As observed in the homogenates, norepinephrine and dopamine enhanced iPGE formation by the intact tissue. Phospholipase A also stimulated iPGE synthesis by the whole ganglia. The effect of phospholipase A was antagonized by dibutyryl cyclic AMP but not by dibutyryl cyclic GMP. The results suggest that neuronally synthesized prostaglandins may be available for modulating adrenergic neuron function and that endogenous neuronal constituents such as catecholamines and cyclic AMP may influence the activity of the prostaglandin synthetase system.
RADIOIMMUNOASSAY OF METHIONINE‐AND LEUCINE‐ENKEPHALINS IN REGIONS OF RAT BRAIN AND COMPARISON WITH ENDORPHINS ESTIMATED BY A RADIORECEPTOR ASSAY
Authors: Gros C. , Pradelles P. , Rouget C. , Bepoldin O. , Dray F. , Fournie‐Zaluski M. C. , Roques B. P. , Pollard H. , Llorens‐Cortes C. , Schwartz J. C.
Published: December 2006

Abstract— Radioimmunoassays (RIAs) selective for methionine‐enkephalin (Met‐ENK) and leucineenkephalin (Leu‐ENK) have been developed using competition towards binding of 10 pM 125I‐enkephalins to antibodies raised in rabbits against ENKs coupled to ovalbumin with carbodiimide. The high sensitivity of the RIAs (IC50 0.57 nm and 0.55 nm for Met‐ and Leu‐ENK, respectively) allowed estimation of the enkephalin content in extracts of all rat brain regions. Regional levels are compared with those determined on the same extracts by a radioreceptor assay (RRA) using competition towards binding of 5 nm [3H]Leu‐ENK to rat striatal membranes. Optimal conditions for killing the animals and extracting the endorphins have been carefully investigated: killing by rapid microwave irradiation was not found necessary as long as brain regions were homogenized into 0.1 n‐HCl before deproteinization.

Marked differences both in total endorphins (RRA) and ENKs (RIA) between regions are observed with similar ranking of the various regions: highest levels are found in striatum and hypothalamus and lowest in cerebellum and hippocampus. In each region the total ENK levels (RIA) represent only 2–13% of the total endorphins (RRA) suggesting the presence of large amounts of endorphins other than the ENKs.