bluuebunny/crossref_metadata_2025 huggingface dataset:
CHANGES IN THE PROTEIN COMPOSITION OF MOUSE BRAIN MYELIN DURING DEVELOPMENT
Authors: Morell P. , Greenfield S. , Costantino‐Ceccarini E. , Wisniewski H.
Published: October 2006

Abstract— Myelin was isolated from the brains of mice at various ages by a procedure involving a final purification on a continuous CsCl gradient. Myelin protein accumulated throughout development, increasing from 0.25 mg of protein/brain at 8 days of postnatal age to 3.5 mg of protein/brain at 300 days, although the rate of accumulation was greatest at about 21 days of age. Quantitative studies of the protein composition of these samples were carried out, utilizing discontinuous polyacrylamide gel electrophoresis in buffers containing sodium lauryl sulphate. Mouse brain myelin, contained (in order of increasing molecular weight) two basic proteins, an uncharacterized doublet, proteolipid protein, and a group of high molecular weight proteins. There were marked changes in the quantitative distribution of these proteins with increasing postnatal age. The basic protein fraction of total myelin protein increased from about 18 per cent at 8 days to 30 per cent at 300 days of age. Proteolipid protein increased even more dramatically, from 7 to 27 per cent in the same time interval. These chemical studies were correlated with ultrastructural investigations, both of the developing myelin sheath in situ and the isolated myelin obtained from mice of various ages. A hypothesis, relating the observed changes in protein composition of myelin during development to its mode of formation, is developed. Another subcellular fraction, separated from myelin, by virtue of its greater density in a CsCl gradient, was also studied. It was a vesicular, membranous fraction present at a level of 0.35 mg of protein/brain at all ages and was related to myelin in terms of protein composition.
THE ACTION OF CALF BRAIN SIALIDASE ON GANGLIOSIDES, SIALOGLYCOPROTEINS AND SIALOGLYCOPEPTIDES
Authors: Heijlman J. , Roukema P. A.
Published: October 2006

Abstract— In agreement with other investigators it has been shown that endogenous as well as added gangliosides are a substrate for brain sialidase. The release of sialic acid was enhanced in the presence of Triton X‐100; this might be due to the action of the detergent on the ganglioside micelles. The sialic acid release from endogenous gangliosides was observed over 48 h and compared with the effect of the sialidase on the endogenous glycoproteins. Though the hydrolysis of sialic acid from gangliosides is much faster in the first hours, after 48 h 40 per cent of the total bound sialic was released from both substrates at pH 4.0 and 37°C.

Sialoglycopeptides obtained from brain glycoproteins are also metabolized by the sialidase. No effect of Triton X‐100 on this substrate has been observed. From sialoglycopeptides, fractions can be obtained by DEAE‐Sephadex A‐50 column chromatography with a sialic acid content from 8 to 26 per cent. The fractions with a high sialic acid content were about equally active towards brain sialidase as gangliosides. The results agree with the similar turnover rate observed for the carbohydrate chains from gangliosides and glycoproteins, but are in contrast to the observations of other investigators who have stated that glycoproteins are a poor substrate for brain sialidase. In our experiments bovine and ovine submaxillary mucins and sialyl‐lactoses showed only slight activity compared to gangliosides and selected brain sialoglycopeptides.
METABOLISM OF GLUCOSE AND FREE AMINO ACIDS IN BRAIN, STUDIED WITH 14C‐LABELLED GLUCOSE AND BUTYRATE IN RATS INTOXICATED WITH CARBON DISULPHIDE
Authors: Tarkowski S. , Cremer Jill E.
Published: October 2006

Abstract— The effect of 15 h continuous exposure to CS2 on the metaboliam of glucose and free amino acids in the brain of rats was studied. CS2 caused a moderate hypoglycaemia. There were also changes in the amounts of some amino acids in the brain. Glutamate and γ‐aminobutyrate were lower whereas glutamine was markedly increased. Comparative studies in vivo of the metabolism of [2‐14C]glucose and [1‐14C]butyrate indicated that CS2 did not affect glycolysis or the incorporation of 14C from glucose into amino acids except into γ‐aminobutyrate which was reduced. Contrary to the findings with [14C]glucose, CS2 provoked distinct changes in the labelling of amino acids when [14C]butyrate was the precursor. The most notable change was a markedly increased incorporation of 14C into glutamine. Based on the two‐compartment model of brain glutamate the experimental findings indicated that CS2 affected metabolism associated with the ‘small’ pool of glutamate but had a minimal effect on metabolism associated with the ‘large’ glutamate pool. The possibility is suggested that the changes observed involved an increased rate of ammonia removal. The low incorporation of 14C into γ‐aminobutyrate from either precursor is consistent with other evidence showing that CS2 interferes with pyridoxal phosphate‐dependent enzymes.
CITRATE OXIDATION IN THE CYTOPLASMIC FRACTION OF RAT BRAIN
Authors: Gromek A. , Rafałowska Urszula
Published: October 2006

Abstract— The cytoplasmic fraction derived from rat brain was shown to possess the ability to oxidize citrate in the presence of NADP, but not in that of NAD. The rate of citrate oxidation is limited by the rate of the aconitase‐catalysed isomerization. The dependence of the reaction rate on the protein, citrate and NADP concentrations, and on reaction time, was determined. It was found that 2‐oxoglutarate and NADPH, both formed in the citrate oxidation reaction, do not appear in amounts equivalent to the losses of citrate. The possible ways of utilization of the above products in the rat brain cytoplasmic fraction are discussed.

It is suggested that the oxidation of citrate in rat brain cytoplasm may proceed–among other metabolic routes–through its conversion into isocitrate (aconitase) and then 2‐oxoglutarate (NADP dehydrogenase) and oxaloacetate (aspartate aminotransferase). In addition it has been shown that hypoxia may markedly effect the activity of the cytoplasmic citrateoxidizing system.
THE USE OF PHOSPHOLIPASE C IN THE STUDY OF RECEPTORS FOR NEUROMUSCULAR BLOCKING AGENTS
Authors: Simpson L. L.
Published: October 2006

Abstract— Segments of diaphragmatic muscle and cerebral nerve‐ending particles from the rat were treated exhaustively (180 min) with high concentrations of phospholipase C (300 μg/ml) (EC 3.1.4.3). This enzyme caused loss of approx. 50 per cent of muscle membrane P and 70 per cent of nerve‐ending membrane P. At lower concentrations (3 μg/ml; 180 min), phospholipase C released 25 per cent muscle membrane P and 55 per cent of nerve‐ending membrane P. At the lower concentration (3 μg/ml; 180 min), the enzyme caused a slow but progressive loss (90 per cent) of muscle twitch amplitude evoked by nerve stimulation (phrenic nerve‐hemidiaphragm preparation). Loss of muscle twitch amplitude was notably slowed by removal of the enzyme. Phospholipase C‐treated neuromuscular junctions developed no resistance to hemicholinium, botulinum toxin, or d‐tubocurarine. Such preparations were unusually sensitive to the neuromuscular blocking action of di‐isopropylfluorophosphate. The data do not encourage a belief that phospholipids which are substrates for phospholipase C are receptors for hemicholinium, botulinum toxin, d‐tubocurarine or di‐isopropylfluorophosphate.
SOME EFFECTS OF DIETARY VITAMIN B6 DEFICIENCY AND 4‐DEOXYPYRIDOXINE ON γ‐AMINOBUTYRIC ACID METABOLISM IN RAT BRAIN
Authors: Bayoumi R. A. , Kirwan J. R. , Smith W. R. D.
Published: October 2006

Abstract— Investigations of the respective effects of dietary vitamin B6 deficiency and 4‐deoxypyridoxine (a vitamin B6 antagonist) on GABA metabolism in rat brain have been carried out. No convulsions were observed in rats subjected to either treatment. GABA levels were lowered by both treatments, the greatest diminutions being found with the dietary deficiency. Glutamic acid decarboxylase activity was reduced under both conditions, but the loss of activity in the B6 deficiency experiments could be attributed to cofactor depletion, whereas in the deoxypyridoxine experiments the loss of activity appears to be due to lower levels of available apoenzyme. The activity of GABA‐transaminase was not affected by deoxypyridoxine treatment and only moderately reduced in the B.5 deficient animals.
SAXITOXIN TETRODOTOXIN AND THE METABOLISM AND CATION FLUXES IN ISOLATED CEREBRAL TISSUES
Authors: Bull R. J. , Trevor A. J.
Published: October 2006

Abstract—Saxitoxin and tetrodotoxin at low concentrations (10−7‐10−8M) exerted similar inhibitory effects on the increase in lactate production and the redistrjbution of Na+and K+that normally accompany electrical stimulation of rat cerebral cortical slices. In contrast, the toxins exerted dissimilar effects on the production of lactate in response to low concentrations of Ca2+in the medium. Inhibition by tetrodotoxin occurred at a higher concentration of Ca2+and was significantly greater than that produced by saxitoxin at concentrations of Ca2+below 0.75 mM. These differences were not related to differential effects on the redistribution of Na+and K+under such conditions. The toxins had different effects on Ca2+influx. Tetrodotoxin, but not saxitoxin, inhibited the influx of Ca2+in the absence of electrical stimulation. The influx of Ca2+increased when electrical pulses were applied and tetrodotoxin inhibited this increase, whereas saxitoxin potentiated influx of Ca2+during stimulation. Our results suggest that metabolic responses to conditions that increase excitability are not governed solely by changes in the distribution of Na+and K+. The differential effects of the toxins on Ca2+fluxes suggest that one site of Ca2+entry during electrical stimulation may be functionally independent of Na+entry.
POTENTIOMETRIC AND COLORIMETRIC METHODS FOR THE ASSAY OF 2′,3′‐CYCLIC NUCLEOTIDE 3′‐PHOSPHOHYDROLASE1
Authors: Kurihara T. , Takahashi Y.
Published: October 2006

Abstract— A potentiometric titration method for the assay of 2′,3′‐cyclic nucleotide 3′‐phosphohydrolase is presented. Progress curves of the reaction were recorded automatically by pH‐stat. 2‐Mercaptoethanol was added to the reaction mixture to maintain a linear rate of reaction. The method is suitable for obtaining kinetic parameters and can be used for the rapid assay of 2′,3′‐cyclic nucleotide 3′‐phosphohydrolase in nervous tissues. An improved colorimetric method for estimation of 2′,3′‐cyclic nucleotide 3′‐phosphohydrolase activity at the optimum pH is described. This method employs the two‐step procedure in which decyclization by 2′,3′‐cyclic nucleotide 3′‐phosphohydrolase and dephosphorylation by Escherichia coli alkaline phosphatase (EC 3.1.3.1) are carried out separately under the optimum conditions for each enzyme. The method is sensitive and most convenient for routine assays.
ANALYSE ELECTROPHORETIQUE COMPAREE DES PROTEINES CEREBRALES TOTALES, SOLUBLES ET PARTICULAIRES, CHEZ CINQ SOUCHES DE SOURIS
Authors: Bobillier P. , Seguin S. , Renaud B. , Valatx J. L.
Published: October 2006

Résumé

Nous avons compareé chez cinq souches de souris adultes Quaking (Qk), C57BL/6, CBA, DBA/2 et CS7BR la distribution des protéines cérébrales totales (solubles en milieu salin ou détergent, acides à pH 8,9 ou basiques à pH 4,3) de fractions subcellulaires obtenues par séparation électrophorétique sur gel de polyacrylamide en gradient discontinu de pH.

Chez le mutant Qk compareéà son témoin des différences quantitatives significatives et une mobilityéélectrophorétique anormale sont mises en évidence respectivement au niveau des protéines acides à poids moléulaire élevé de la myéline et au niveau des protéines solubles à poids moléulaire faible de la myéline et des synaptosomes. Entre Qk et témoin, aucune différence n'est déelable parmi les protéines des fractions nucléires, mitochond‐riales ou microsomales.

Les incubations in vivo d'acides aminés tritiés réalisées chez la souris Qk révélent une augmentation de I'incorporation du préurseur dans deux fractions des protéines solubles, acides de la fraction cytoplasmique non particulaire.

Les profils électrophorétiques des protéines cérébrales étudiéés chez trois autres souches consanguines (CBA, DBA/2 et C57BR) sont identiques à I'exception de DBA/2 dont les protéines solubles et acides du surnageant cytoplasmique sont caractérisées par deux bandes mineures additionnelles. Les anomalies protéiques observées sont discutées en fonction des troubles de la myélinisation du systéme nerveux central et de la possibilityé d'une induction cellulaire multienzymatique d'origine génétique.
THE RELEASE AND MOLECULAR STATE OF MAMMALIAN BRAIN ACETYLCHOLINESTERASE
Authors: Hollunger E. G. , Niklasson B. H.
Published: October 2006

Abstract—By incubating the particulate fraction of caudate nucleus from calf brain in ion‐free media, about 90 per cent of the AChE activity was brought into solution. The effects of different salts, EDTA and tetracaine on the release were studied. The mol. wt. of the enzyme was determined by gel filtration. About 90 per cent of the activity in a fresh preparation appeared in a form with mol. wt. 80,000. During storage this form was gradually transformed into forms with higher mol. wts. The effects of changes in the ionic environment on the aggregation were investigated. Purification attempts always resulted in the transformation of the enzyme into high mol. wt. forms. If the release was performed in the presence of DEAE‐Sephadex‐A25, the enzyme no longer aggregated. The cytosol fraction always contained some AChE activity; the significance of the presence of AChE in this fraction is discussed.
RATES OF CEREBRAL GLUCOSE UTILIZATION IN RATS ANAESTHETIZED WITH PHENOBARBITONE
Authors: Strang R. H. C. , Bachelard H. S.
Published: October 2006

Abstract—

Intraperitoneal injection of phenobarbitone (250 mg/kg body wt.) into rats caused increased brain concentrations of glucose (100 per cent), glucose 6‐phosphate (16 per cent) and ATP (12 per cent) and decreased concentrations of lactate (33 per cent) and ADP (15 per cent). A 31 per cent decrease in glutamate content was not statistically significant. No significant change occurred in the cerebral contents of glycogen or creatine phosphate.

The rates of increase in the brain of specific activities, in the first few minutes after systemic injection of [U‐14C]glucose, of glucose, lactate, glutamate and glycogen were all halved by phenobarbitone. Calculated flux rates of 14C from glucose into metabolic intermediates and from lactate to glutamate were also decreased by 27–47 per cent; the effects on rate constants showed inconsistencies. The rate constants for conversion of glucose to lactate and to glutamate were decreased by 60–70 per cent, but that from lactate to glutamate was virtually unchanged. The rate constant for the flux from glucose to glycogen was reduced by 39 per cent, but the accumulation of glucose meant that the actual flux into glycogen increased by 20 per cent.

The results are interpreted in terms of an effect of the barbiturate not only on glucose transport, but also at an enzymic stage in glycolysis, possibly hexokinase or phosphofructokinase.
PROPERTIES AND METABOLISM OF SOLUBLE LIPOPROTEINS CONTAINING CHOLINE AND ETHANOLAMINE PHOSPHOLIPIDS IN RAT BRAIN
Authors: Benjamins Joyce A. , McKhann G. M.
Published: October 2006

Abstract— Choline and ethanolamine phospholipids in the 105,000 g supernatant fraction of rat brain exhibited density and electrophoretic properties consistent with their binding to protein. About 40% of these two phospholipids were bound to soluble lipoproteins, whereas the remainder appeared to be associated with particulate complexes. Following intracranial injection of [2‐3H]glycerol, the specific radioactivities of the choline and ethanolamine phospholipids in the supernatant fraction were higher than those in the microsomal fraction at all time points examined, from 15 min to 12 h after injection. The properties of cytoplasmic lipoproteins containing choline and ethanolamine phospholipids have been compared with those which we have previously described containing sulphatide.
EFFECT OF UNDERNUTRITION ON CELL FORMATION IN THE RAT BRAIN
Authors: Patel A. J. , Balázs R. , Johnson A. L.
Published: October 2006

Abstract—Rats were undernourished by approximately halving the normal food given from the 6th day of gestation throughout lactation. Growth of the foetuses was nearly normal, in marked contrast to the severe retardation caused by undernutrition during the suckling period. In comparison with controls the size and the DNA content of the brain were permanently reduced by undernutrition during the suckling period: this effect was relatively small, approx. 15 per cent decrease at 21 and 35 days. The rate of14C incorporation into brain DNA at 30 min after administration of [2‐14C] thymidine was taken as an index of mitotic activity; compared with controls there was severe reduction in mitotic activity (maximal decrease by about 80 per cent at 6 days in the cerebrum and by 70 per cent at 10 days in the cerebellum). The rate of acquisition of cells was calculated from the slopes of the logistic curves fitted to the estimated DNA contents. In normal animals the maximal slope was attained at 2·7 days and at 12·8 days after birth in cerebrum and cerebellum respectively; the daily acquisition of cells at these times was 4·8 × 106and 18 × 106cells respectively. The fractional increase in cell number at the maximum was 5·4 percent per day in the cerebrum and 15·2 per cent per day in the cerebellum. The rate of acquisition of cells relative to the rate of mitotic activity was higher in the brains of undernourished animals than in controls. One of the compensatory mechanisms for the severe depression of mitotic activity in the brain of undernourished animals Seems to involve a reduction in the normal rate of cell loss.
THE UPTAKE OF AMINO ACIDS BY THE INTACT OLFACTORY BULB OF THE MOUSE: A COMPARISON WITH TISSUE SLICE PREPARATIONS
Authors: Neidle A. , Kandera J. , Lajtha A.
Published: October 2006

Abstract— Intact olfactory bulbs from 8‐ to 15‐day‐old mice were compared to slices of olfactory bulb and cerebral hemisphere with respect to uptake of amino acids, respiratory rate, levels of ATP, retention of sodium and potassium, and extracellular space. The uptake of amino acids was lower in intact bulbs than in slice preparations, both in regard to initial rates of uptake and to final steady state levels, at external amino acid concentrations from 0·2 to 2·0mM. Uptake was lower in bulbs attached to brain than in those separated from it and somewhat higher in the half of the bulb closer to the cut surface. In all preparations the uptake of glutamic acid and glycine was highest, uptake of histidine and valine was intermediate, and uptake of lysine was lowest. These differences between intact bulbs and slices could not be correlated with differences in respiratory rate, levels of ATP, or changes in levels of Na+ or K+ ions. Increases in dextran and inulin spaces, however, were greatest in preparations having the highest rates of amino acid uptake. Although for several amino acids the maximal velocity of uptake (Vmax) was 4‐fold higher in slices of bulb than in intact bulbs, the affinity of amino acids to their carrier systems (Km) was similar, an indication that the same transport process was operative in both cases. On the basis of these results we propose that intact olfactory bulbs incubated in vitro possess a regulatory mechanism for the limitation of amino acid uptake that is absent or diminished in slices.
Turnover of brain adrenergic transmitters in Quaking mice
Authors: Kempf E. , Greilsamer J. , Mack G. , Mandel P.
Published: October 2006

Quaking mice, neurological mutants of the C57 BL/6J strain have a markedly deficient myelination of the CNS(Sidman, Dickie and Appel, 1964). Many studies have been carried out on their lipids (Jacque, Harpin and Baumann, 1969; Neskovic, Nussbaum and Mandel, 1969, 1970; Kurihara, Nussbaum and Mandel, 1970; Sarlieve, Neskovic and Mandel, 1971; Singh, Spritz and Geyer, 1971) for this reason, but little attention has been paid to other aspects of their aminergic transmitters metabolism. During the course of our work, Tillement, Debarle, Simon and Boissier (1970) reported on the transmitter levels in Quaking mice. The reasons for thinking that the monoamine metabolism of these mice might be altered are as follows. The trembling might be associated with a change in the activity and therefore metabolism of dopaminergic structures. Chronic stress due to permanent tremor might induce changes in norepinephrine metabolism. Since there are changes in the sleep patterns of Quaking mice (Valatx and Jouvet, 1971), there might be changes in brain serotonin metabolism. This study of the turnover of norepinephrine, dopamine and serotonin in the whole brains of control and Quaking mice is the preliminary to detailed examination of the turnover of the transmitters in well‐defined brain regions.
ADENOSYLMETHIONINE DECARBOXYLASE IN DEVELOPING RAT BRAIN
Authors: Schmidt G. L. , Cantoni G. L.
Published: October 2006

Adenosylmethionine decarboxylase from rat brain has been found to be similar to the same enzyme isolated from other rat tissues in regard to kinetic parameters, pH optimum, putrescine requirement, and subcellular location. Evidence is presented that pyridoxal phosphate is not the functional cofactor in enzymatic decarboxylation by the rat brain preparation. The capacity for spermidine synthesis in developing rat brain was determined by measurement of the activity of adenosylmethionine decarboxylase. The activity increased dramatically after 10 days of postnatal age. This increase occurred after the period of maximum nucleic acid synthesis, an observation which suggests that spermidine may have a role in the functional development of the brain.
ON THE MECHANISM OF TAURINE TRANSPORT AT BRAIN CELL MEMBRANES
Authors: Lähdesmäkt P. , Oja S. S.
Published: October 2006

One non‐saturable and two saturable transport systems were demonstrated for taurine in rat brain slices. One of the saturable systems, designated β, is characterized by a high asnity for taurine and a low transport capacity, while the other, designated ω, by a low affinity and a high transport capacity. 2,4‐Dinitrophenol inhibited the saturable transport of taurine non‐competitively, while hypotaurine. β‐alanine, γ‐aminobutyric acid, N‐methyl‐taurine and L‐cysteic acid inhibited transport competitively. It is thus inferred that the hypothetical carrier sites of taurine at cell membrane recognize to an equal degree strongly ionized electropositive and electronegative ends of an acceptable molecule separated by two or three carbon atoms. Two is the minimal and also the optimal carbon chain length in an acceptable molecule.
THE RELATIONSHIP BETWEEN DNA SYNTHESIS AND NUCLEAR PROTEINS IN THE CEREBRUM AND CEREBELLUM OF 8‐DAY‐OLD RATS
Authors: Burdman J. A. , Szijan I. , Franzoni L. , Argiz C. A. Garcia
Published: October 2006

In‐8‐day‐old rats the higher rate of DNA replication in cerebellum than in cerebrum is accompanied by an enhanced synthesis of nuclear proteins. The greatest difference between the incorporation of tritiated leucine into proteins of cerebral and cerebellar cell nuclei occurs in the acid‐soluble deoxyribonucleoproteins. However, the specific radioactivity of the acidic deoxyribonucleoproteins is similar in both tissues. The relative content of these proteins and the activity of the RNA polymerase is higher in cerebrum than in cerebellum. The results suggest that in the cerebrum of young rats these proteins are mainly concerned with the regulation of RNA synthesis.
BIOGENIC AMINES AND THEIR METABOLITES AS SUBSTRATES FOR PHENOL SULPHOTRANSFERASE (EC 2.8.2.1) OF BRAIN AND LIVER
Authors: Meek J. L. , Neff N. H.
Published: October 2006

Phenol sulphotransferase activity in homogenates of rat liver and brain was determined spectrophotometrically. Rat liver had about 100‐fold more phenol sulphotransferase activity than brain; however, both tissues showed about the same spectrum of activity towards the phenolic compounds tested. Dopamine and its acidic and neutral metabolites and the neutral metabolites of norepinephrine were the compounds most readily sulphury‐lated in vitro. They were also the compounds most readily sulphurylated in vivo when they were injected intraventricularly together with labelled Na2SO4. When labelled Na2SO4 was injected alone, we detected conjugation of endogenous phenols. One of the compounds formed was identified by its chromatographic characteristics as 3‐methoxy‐4‐hydroxy‐phenylethyleneglycol sulphate. We detected other conjugates which appeared to be the sulphate esters of 3,4‐dihydroxyphenylethyleneglycol; 3,4‐dihydroxyphenylacetic acid; and homovanillic acid. In brain, sulphate conjugation may be a major route of metabolism for many of the phenolic compounds related to the biogenic amines and possibly for phenolic drugs which enter the brain.
CATECHOLAMINES IN FETAL AND NEWBORN RAT BRAIN
Authors: Coyle J. T. , Henry D.
Published: October 2006

The levels of dopamine and norepinephrine were determined in the brains of fetal and newborn rats by means of a sensitive, radiometric‐enzymatic assay. Catecholamines were converted to their 3‐O‐methylated derivatives in the presence of catechol‐O‐methyl transferase (EC 2.1.1.1) and [3 H‐methyl]S‐adenosylmethionine; and the [3H]‐derivatives were isolated by selective extraction. The assay had a sensitivity for dopamine and norepinephrine of 100 picograms and was linear to at least 30 nanograms of catecholamines. Both amines were present at 15 days of gestation and increased 15‐fold in content during the last week of gestation. The regional distribution of these neurotransmitters in the brain of the newborn rat correlated with the distribution of their biosynthetic enzymes. An investigation of the effects of reserpine, pheniprazine, α‐methyl‐para‐tyrosine, diethyldithiocarbamate and l ‐DOPA on the levels of dopamine and norepinephrine in the brains of the 18‐day gestational fetus indicated that the levels of these neurotransmitters are under controls similar to those known to occur in the brain of the adult rat.
THE DISTRIBUTION OF SEVERAL AMINO ACIDS IN SPECIFIC GANGLIA AND NERVE BUNDLES OF THE LOBSTER1
Authors: Aprison M. H. , Mcbride W. J. , Freeman A. R.
Published: October 2006

Using the technique of measuring DNP‐amino acid methyl esters by gas‐liquid chromatography, the distribution of alanine, proline, glycine, GABA, glutamate and aspartate was determined in individual ganglia and the associated nerve bundles between these ganglia after isolation from the nervous system of the lobster, Homarus americanus. The brain or supraesophageal ganglion (27.2 mg) and the next 5 thoracic ganglia (varying from 24 to 10 mg in a rostral–caudal direction) as well as the nerve bundles connecting these ganglia were used. GABA and aspartate values varied the most among the individual ganglia; highest values were found in the second and third thoracic ganglia. The levels of alanine, proline, glycine and glutamate varied very little from ganglion to ganglion; however, the values for these amino acids did exhibit some variability among the individual connectives. The highest value for each was in the nerve bundle between the first and second thoracic ganglion. Glycine was present at the highest level of any of the amino acids whereas GABA was at the lowest level in the individual structures assayed.
A SENSITIVE SPECIFIC ENZYMATIC‐FLUOROMETRIC ASSAY FOR HOMOCARNOSINE1
Authors: Young Anne B. , Snyder S. H.
Published: October 2006

We have developed a sensitive and specific assay for homocarnosine in tissues. Homocarnosine is separated from GABA by ion exchange chromatography. After hydrolysis of homocarnosine with swine kidney carnosinase, the evolved GABA is measured by an enzymatic‐fluorometric procedure. As little as 0.1 nmol of tissue homocarnosine can be detected by this procedure. Homoanserine, which would be detected by this assay, can be separated from homocarnosine by thin layer chromatography. No homoanserine could be detected in any tissues examined. There are marked regional variations in levels of homocarnosine in guinea‐pig brain that do not correspond to regional differences in GABA levels.
NOREPINEPHRINE METABOLISM IN THE CENTRAL NERVOUS SYSTEM OF MAN: STUDIES USING 3‐METHOXY‐4‐HYDROXYPHENYLETHYLENE GLYCOL LEVELS IN CEREBROSPINAL FLUID
Authors: Chase T. N. , Gordon Edna K. , Ng L. K. Y.
Published: October 2006

—Levels of 3‐methoxy‐4‐hydroxyphenylethylene glycol (MHPG), a major metabolite of norepinephrine, were measured in human CSF by gas‐liquid chromatography. MHPG concentrations were similar in both ventricular and lumbar CSF samples; about 30 per cent of the MHPG from either source occurred as the sulphate conjugate. There was relatively little entry of intravenously infused [14C]MHPG into lumbar spinal fluid. Both α‐methylparatyrosine, an inhibitor of tyrosine hydroxylase, and fusaric acid, an inhibitor of dopamine‐β‐hydroxylase, significantly diminished MHPG values. On the other hand, doses of l‐DOPA or probenecid, sufficient to substantially elevate CSF levels of the dopamine metabolite, homovanillic acid, failed to alter the spinal fluid content of MHPG. CSF concentrations of MHPG in patients with Parkinson's disease or the other central nervous system disorders studied did not differ significantly from control levels. The results suggest that MHPG values in CSF may provide an index to norepinephrine metabolism in the central nervous system of man.
REGIONAL DISTRIBUTION OF GLUTAMIC ACID DECARBOXYLASE IN THE DEVELOPING BRAIN OF THE PYRIDOXINE‐DEFICIENT RAT
Authors: Bayoumi R. A. , Smith W. R. D.
Published: October 2006

—Glutamic acid decarboxylase was determined in seven brain regions: hypo‐thalamus; midbrain; thalamus; corpus striatum; cerebral cortex‐hippocampus; medulla‐pons; and cerebellum, of suckling rats subjected to Vitamin B6 deficiency for 2 weeks from birth; of adult rats subjected to the deficiency for 5 weeks and of their respective controls. Large regional variations in the enzyme activity were found in brains of both adult and suckling control rats. The activity of the enzyme (assayed without pyridoxal phosphate) and its saturation with endogenous cofactor were markedly reduced in all brain regions of both suckling and adult pyridoxine‐deficient rats. The apoenzyme (activity assayed with pyridoxal phosphate), in adult rat brain, showed no change with the deficiency in all regions except in the cerebellum where it increased slightly. In pyridoxine‐deficient suckling rat brain, the apoenzyme increased substantially in all regions suggesting a process of enzyme induction. The increase in apoenzyme varied from region to region.
REGIONAL AND SUBCELLULAR DISTRIBUTION OF CHOLINE ACETYLTRANSFERASE IN THE BRAIN OF RATS1
Authors: Wajda I. J. , Manigault I. , Hudick J. P. , Lajtha A.
Published: October 2006

—Homogenates of corpus striatum, cerebral cortex and hypothalamus excised from rat brain were fractionated on discontinuous Ficoll and sucrose density gradients, and the distribution of choline acetyltransferase (ChAc) in the mitochondrial and synaptosomal fractions was determined. In the hypothalamic and cortical regions the fractions enriched in synaptosomes showed much higher activity of ChAc than those containing mainly mitochondria. On the other hand, the corpus striatum showed an equal distribution of ChAc activity in those two fractions. The localization of ChAc was also studied in the postnuclear supernatants obtained from three brain regions, using continuous sucrose density gradients. The distribution of ChAc was compared to that of monoamine oxidase (MAO), potassium and protein. When the pellets obtained from the fractions collected from the gradient were suspended in sucrose, the peak of ChAc activity was close to that of MAO in all three brain regions. When 0.1 mm EDTA +1% butanol was used in order to liberate the occluded form of ChAc, the maximum liberation occurred in lighter fractions, resulting in a shift of the activity peak toward the top of the gradient. This was found with fractions from hypothalamic and cortical regions. In the striatum, the liberated ChAc remained in the same fractions as the occluded enzyme. The results indicate that ChAc is liberated only in those fractions where it is present in synaptosomes. In agreement with the results on the discontinuous gradients this occurs in particles of lower density than mitochondria in cortex and hypo‐thalamus, but in particles of similar density to mitochondria in the corpus striatum, indicating regional differences in the distribution of ChAc in the brain. K+ containing particles centrifuged in less dense fractions than those containing ChAc, indicating that synaptosomes are heterogeneous with respect to these two marker substances.
DDT EFFECT ON 32P INCORPORATION FROM γ‐LABELLED ATP INTO PROTEINS FROM LOBSTER NERVE
Authors: Doherty J. D. , Matsumura F.
Published: October 2006

The insecticide DDT (1,1,1 trichloro‐2,2‐bis‐(p‐chlorophenyl) ethane) was found to affect the amount of 32P from [γ‐32P] ATP incorporated into proteins derived from lobster peripheral nerves in a variety of ways depending upon the relative concentrations of ATP, Na+, K+, Mg2+, and Ca2+. When a high concentration of ATP (2.5 ± 10−5m) was used DDT (10−5m) inhibited the incorporation and reversed the increased incorporation caused by ouabain. At low concentration of ATP (8.6 ± 10 −8m), DDT inhibited the incorporation when the buffer contained Mg2+ and Na+ or K+ alone, but when the buffer contained Mg2+ and both Na+ and K+ together, DDT consistently caused an increased amount of 32P to be incorporated. The ability of DDT to cause increases in incorporation of 32P into the lobster nerve proteins was found to parallel many of the properties that this compound shows when allowed to poison crustacean nerves. For example: the effect was negatively temperature dependent, Ca2+ lowered the incorporation in the presence of DDT, and DDT consistently caused greater amounts of 32P to be incorporated than its less potent analog DDE (1,1‐dichloro‐2,2‐bis‐(p‐chlorophenyl)ethylene). The proteins that were affected by DDT were microsomal in nature and could be centrifuged from supernatant by recentrifuging at 149,000 g. The possibility that this system may be the actual target through which DDT causes its characteristic interferences of the ionic conductance changes associated with the action potential are discussed.
THE UPTAKE OF GABA INTO RAT SPINAL ROOTS
Authors: Davies J. , Johnston G. A. R.
Published: October 2006

—Dorsal and ventral roots, dissected from rats anaesthetized with sodium pentobarbitone, accumulated three to four times more GABA than l‐glutamate, 1‐aspartate or glycine during 30 min incubation at 37°C. GABA was taken up into spinal roots by a structurally specific, sodium‐dependent process with an apparent Km of approx. 3 × 10−5m. This uptake process appears to be very similar to that described in rat brain, spinal cord and dorsal root ganglia.
TIME‐DEPENDENT CHANGES IN BRAIN BIOGENIC AMINE DYNAMICS FOLLOWING CASTRATION IN MALE RATS1
Authors: Bernard B. K. , Paolino R. M.
Published: October 2006

—Alterations in whole‐brain and hypothalamic levels of serotonin (5‐HT), 5‐hydroxyindoleacetic acid (5‐HIAA), norepinephrine (NE), dopamine (DA) as well as the turnover rates of NE and DA of adult male rats were analysed fluorometrically at either 3 weeks or 6 weeks following castration. Significant increases were observed in whole‐brain (minus hypothalamus) 5‐HIAA levels and hypothalamic DA levels, fractional rate constants and utilization rates at the 3 but not the 6 week intervals. Elevated levels of 5‐HT were observed at both time intervals while an increase in whole‐brain DA was seen only at the 6 week interval. Whole brain NE turnover rates of castrated animals did not differ significantly from those of sham‐castrate control animals at either test interval. However, a tendency toward increased hypothalamic NE turnover rates was seen in the castrated animals. These biochemical changes resulted in decreased NE/5‐HT and DA/5‐HT ratios for the castrate rats as compared to controls.

The results are discussed in relation to emotional and aggressive behavior and are interpreted as being consistent with the hypothesis purporting an inhibitory role for 5‐HT and excitatory role for NE and DA in sex‐specific behavior patterns including aggression.
AXONAL TRANSPORT OF PHENYLETHANOLAMINE‐N‐METHYLTRANSFERASE IN TOAD SCIATIC NERVE
Authors: Wooten G. F. , Saavedra J. M.
Published: October 2006

—The presence of phenylethanolamine‐N‐methyltransferase (EC 2.1.1.‐) and dopamine‐β‐hydroxylase (EC 1.14.2.1) activities was demonstrated in the sciatic nerve of the toad, Bufo marinus. The rates of accumulation of phenylethanolamine‐N‐methyltransferase (PNMT) and dopamine‐β‐hydroxylase (DBH) proximal to a ligation of the sciatic nerve were studied. DBH accumulated proximal to the ligation at a more than 10‐fold faster rate than PNMT. By measuring the rate of loss of enzyme activity distal to a ligation, an estimate of per cent clearance of each enzyme was made. Based on the per cent of enzyme activity free to move, the absolute transport rates for each enzyme were estimated to be: PNMT, 3.6 mm/24 h; DBH, 102 mm/24 h. PNMT activity (89 per cent) was recovered in the soluble fraction of sciatic nerve homogenates with no change occurring in the subcellular distribution of the enzyme proximal to ligations. In contrast, 43 per cent of DBH activity was found in the soluble fraction of sciatic nerve homogenates; but a disproportionate increase in paniculate DBH activity was found proximal to sciatic nerve ligations. Reduction of toad body temperature to 4°C resulted in a complete but totally reversible block of the axonal transport of both PNMT and DBH.
EFFECT OF LIGHT ON GANGLIOSIDES FROM CALF RETINA AND PHOTORECEPTORS
Authors: Dreyfus H. , Urban P. F. , Bosch P. , Edel‐Harth S. , Rebel G. , Mandel P.
Published: October 2006

—The gangliosides of the whole calf retina and the rod outer segments have been analysed. This has been done in two functional states: before and after stimulation by light. After exposure to light no statistically significant change in the gangliosides of the whole retina was observed, but a 40 per cent increase in concentration was found in the rod outer segments. This difference was apparent only when using the same batch of rod outer segments. The major ganglioside in the whole calf retina is GD3 which accounts for 46 per cent of the total. Three other gangliosides GD1a, GD1b and GT1 are quantitatively important, each being between 12 and 16 per cent. GQ1, GM1, and GM3 are minor constituents. In contrast to the chicken retina, GM2 was not detected. The ganglioside N‐acetylneuraminic acid of the rod outer segments accounts for only 1 per cent of the gangliosides of the whole retina. The composition of the gangliosides in the rod outer segments is essentially the same as that of the whole retina. No difference in the relative proportion of the gangliosides of either the rod outer segments or the whole retina was observed after exposure to light.
OCCURRENCE AND LOCALIZATION OF BRAIN PHENOLSULPHOTRANSFERASE
Authors: Foldes A. , Meek J. L.
Published: October 2006

—Rat brain contains the enzyme which forms sulphate conjugates of phenols, phenolsulphotransferase (EC 2.8.2.1), but the physiological role of the enzyme is unclear. The enzyme is unevenly distributed in rat brain, with the activity 13 times higher in the hypothalamus than in the cerebellum. Phenolsulphotransferase does not seem to be primarily located in glial cells. Cultured cells (type C6 astrocytoma) derived from rat glia had less than 1 per cent of the phenolsulphotransferase activity of whole rat brain. Sulphate conjugation of neutral compounds may be important in their removal from brain. The pineal and pituitary glands, areas outside the blood‐brain barrier had very low phenolsulphotransferase activity. The activity of the enzyme in brain varied widely among different species: rabbit and rat had much higher levels of activity than mouse or frog; the activity in human brain was intermediate. Phenolsulphotransferase also occurred in other organs, including liver, heart, testes, lung, spleen, salivary glands, and intact or decentralized superior cervical ganglion. There was no correlation of enzyme activity with adrenergic or cholinergic innervation, or with the known roles of various tissues in drug metabolism or detoxification. The enzyme activity does not seem to be under neuronal control since ganglionectomy did not affect the phenolsulphotransferase activity of salivary glands. The precise localization of phenolsulphotransferase remains to be established, as well as the physiological importance of sulphate conjugation of phenols in brain and other organs.
INTRACELLULAR LOCALIZATION OF PHENOL SULPHOTRANSFERASE IN RAT BRAIN
Authors: Jansen G. S. I. M. , Vrensen G. F. J. M. , Van Kempen G. M. J.
Published: October 2006

—The intracellular localization of phenol sulphotransferase in rat brain was studied The distribution pattern found after differential centrifugation closely resembles that of lactate dehydrogenase and does not change during postnatal development. The distribution of the enzyme in discontinuous and continuous sucrose gradients, however, shows a deviation from the lactate dehydrogenase pattern and a shift towards a higher sucrose concentration during development. In the adult the phenol sulphotransferase coincides with monoamine oxidase, succinate dehydrogenase and β‐glucuronidase. Disruption experiments, purification of mitochondria and electron microscopy exclude localization of phenol sulphotransferase in mitochondria. These studies support the idea of phenol sulphotransferase as a cytoplasmic enzyme with a preferential binding to or localization in oligodendroglial cells or, more probably, a specific type of synaptosomes.
INTERRELATIONSHIPS AMONG THE LEVELS OF ATP, ADENOSINE AND CYCLIC AMP IN INCUBATED SLICES OF GUINEA‐PIG CEREBRAL CORTEX: EFFECTS OF DEPOLARIZING AGENTS, PSYCHOTROPIC DRUGS AND METABOLIC INHIBITORS
Authors: Huang M. , Daly J. W.
Published: October 2006

—Adenine nucleotides of guinea‐pig cerebral cortical slices were labelled during a 40 min incubation with [14C]adenine. Subsequent incubation of cortical slices with depolarizing agents, such as veratridine, ouabain, batrachotoxin and high concentrations of potassium ions, or with certain psychotropic drugs such as chlorpromazine, chlorimipramine or prenylamine resulted in a reduction in both endogenous and radioactive ATP, accompanied by a marked increase in levels of both endogenous and radioactive cyclic AMP. Reduction of ATP levels during incubation with depolarizing agents, such as veratridine, is probably associated with increased activity of membranal Na+‐K+‐activated ATPase, while the reduction elicited by psychotropic drugs is proposed to be due to inhibition of mitochondrial synthesis of ATP. With both classes of compounds reduction of ATP levels results in enhanced formation and efflux of adenosine which stimulates formation of cyclic AMP from intracellular ATP in the compartments of brain slices which contain the cyclic AMP‐generating systems. Certain classical metabolic inhibitors such as 2,4‐dinitrophenol, azide, 1,2‐naphthoquinone‐8‐sulfonate and cyanide also reduce ATP levels and in the case of 2,4‐dinitrophenol, cyanide, and azide elicit small but significant accumulations of cyclic AMP. With certain metabolic inhibitors reduction of ATP within the cyclic AMP generating compartments would appear to prevent or reduce the accumulation of cyclic AMP elicited by amines, adenosine or veratridine.
ELECTROPHORETIC STUDY OF 5‐HYDROXYTRYPTOPHAN DECARBOXYLASE FROM BRAIN AND LIVER IN SEVERAL SPECIES
Authors: Cavalli‐Sforza L. L. , Santachiara S. A. , Wang L. , Erdelyi E. , Barchas J.
Published: October 2006

—An electrophoretic investigation in acrylamide gels of 5‐hydroxytryptophan decarboxylase, obtained mostly from mouse, rat, and beef brain and also from beef and human liver, showed electrophoretic differences between species. With the exception of the rat, only one molecular species was found (the same in beef brain and liver). In the rat, polymers form spontaneously and are, at least in part, disaggregated by urea and by triton. Mouse‐rat or beef‐rat molecular hybrids form in the admixtures. No electrophoretic differences were found in five mice strains that were investigated. Techniques of electrophoretic analysis and of assay of 5‐hydroxytryptophan decarboxylase are described, which can be easily applied to other enzymes, provided a substrate is available in radioactive form.
METABOLIC ACTIVITY OF CNS PROTEINS IN RATS AND MONKEYS WITH EXPERIMENTAL ALLERGIC ENCEPHALOMYELITIS (EAE)
Authors: Smith Marion Edmonds , Rauch Helene C.
Published: October 2006

—The metabolic activity of proteins from myelin and non‐myelin fractions of slices of lesions in monkey brains and in spinal cords of Lewis rats with acute experimental allergic encephalomyelitis was investigated using [1‐14C]leucine as a protein precursor. The uptake in vitro of [1‐14C]leucine into the monkey EAE lesions was greatly increased in both the myelin and non‐myelin fractions. Similar findings were made in spinal cord slices of the EAE rat with an average specific activity 341 per cent of control measured in proteins of purified myelin and 415 per cent of control in the non‐myelin protein. The increased uptake appeared with the onset of paralytic symptoms 10–14 days after injection. The increased uptake did not appear to be a result of an increased amino acid pool size as measured with uniformly labelled l‐leucine, valine, arginine and phenylalanine. The increase in specific activity of the myelin protein of the EAE rats was shown to be associated with the peaks characteristic of myelin protein when separated on polyacrylamide gels and the serial slices counted. Most of the radioactivity of both the control and EAE myelin protein migrated with the high molecular weight fraction, and the largest increase in radioactivity in myelin protein appeared in this fraction. Some increase in specific activity was also found in the basic and proteolipid proteins. Four different guinea‐pig antigens were used to induce EAE: whole spinal cord, purified basic protein, purified myelin and basic protein + cerebroside. All caused paralytic symptoms and greatly increased incorporation in vitro of [1‐14C]leucine into spinal cord proteins. The incorporation of [1‐14C]leucine into slices of the inguinal and popliteal lymph nodes of the EAE and Freund's adjuvant control rats were measured and compared with the incorporation into the spinal cord non‐myelin fractions. The specific activity of lymph node proteins was of the order of 10 × that of the non‐myelin protein of the control spinal cord. Invasion of a moderate number of cells of the order of activity of these lymph nodes could account for the large increase in rate of protein synthesis in the EAE nervous tissue. It is concluded that much of the increased protein synthesis could be due to the inflammatory cells, although a small amount of the total increase appears to be associated with myelin protein. Other changes in metabolism of the CNS tissue of the EAE rat include a lower rate of lipid synthesis and a decreased activity of the tricarboxylic acid cycle.