bluuebunny/crossref_metadata_2025 huggingface dataset:
SEDIMENTATION ANALYSIS OF RIBONUCLEIC ACID EXTRACTED FROM ISOLATED MAUTHNER NERVE FIBRE COMPONENTS
Authors: Edström A. , Edström J.‐E. , Hökfelt T.
Published: October 2006

Abstract— Segments of spinal cords from goldfish or from carp were incubated in vitro in the presence of RNA precursors for varying periods of time. Mauthner nerve fibres were isolated from the fresh unfixed tissue, or, for the separate analyses of axon and myelin sheath, from the fixed spinal cord.

The myelinated Mauthner fibre isolated from the incubated spinal cord showed RNA synthesis. A considerable part of the material sedimented at 4S, but part of the nucleic acid was recovered at higher sedimentation values, up to 30S. Newly synthesized RNA was extracted from the isolated myelin sheath as well as from the axon. Isolated myelinated Mauthner fibres were also incubated in vitro with RNA precursors. In this case incorporation occurred exclusively in material sedimenting at 4S or lower. The turnover rate for RNA from the fibre was of a higher order than that of the bulk of RNA from the spinal cord. The findings of RNA synthesis in these tissue components lacking nuclei could possibly be explained as owing to mitochondria.

Studies by electron microscopy demonstrated the extent of purity of the isolated components and it was found that contamination was so small as to make it unlikely that the RNA investigated originated in contaminating tissue.
UPTAKE OF CALCIUM BY SUBCELLULAR FRACTIONS ISOLATED FROM OUABAIN‐TREATED CEREBRAL TISSUES
Authors: Stahl W. L. , Swanson P. D.
Published: October 2006

Abstract— Slices of cerebral cortex were incubated in medium containing 0·75 or 2·8 mM 45CaCl2, in the presence or absence of 0·01–0·1 mm‐ouabain. Ouabain induced accumulation of calcium by slices to a maximum of 4 μmoles/g of tissue/hr (0·75 mm‐CaCl2 in the medium) and to 8 μmoles/g of tissue/hr (2·8 mm‐CaCl2 in the medium). Accumulation of Ca2+ occurred more slowly than loss of K+ from the slices and more closely resembled the pattern of Na+ uptake.

Mitochondrial fractions isolated from ouabain‐treated slices contained significantly more calcium than controls. Inclusion of EDTA in the homogenization medium resulted in decreased amounts of particulate‐bound calcium.

The effect of ouabain on accumulation of calcium is discussed with regard to possible relationships to processes of active and passive transport.
FUCOSE INCORPORATION INTO GLYCOPROTEINS OF MOUSE BRAIN
Authors: Zatz M. , Barondes S. H.
Published: October 2006

—Radioactive fucose was incorporated into glycoproteins of brain in vivo. After intracerebral administration of this precursor, radioactive glycoproteins were the sole detectable product. The glycoproteins formed appeared to have a slow turnover but this was due, at least in part, to re‐utilization of fucose released from degraded glycoproteins. Incorporation of fucose into glycoproteins differed from that of glucosamine, since a much smaller proportion of the radioactive fucose was incorporated into soluble glycoproteins. Fucose was rapidly incorporated into glycoproteins of nerve endings, although there was relatively little incorporation into glycoproteins associated with the soluble component of the nerve‐ending fraction. As found in previous studies with glucosamine, soluble glycoproteins of nerve endings turned over relatively rapidly. Pretreatment with acetoxycycloheximide markedly inhibited incorporation of fucose into glycoproteins of brain. In contrast to the results with glucosamine, comparable inhibition was observed for fucose in all subcellular fractions of brain including the particulate and soluble components derived from the nerve‐ending fraction.
SYNTHESIS OF NUCLEAR RNA IN NERVE AND GLIAL CELLS
Authors: Løsvtrup‐Rein Huguette
Published: October 2006

—Tritium‐labelled RNA precursors were injected at 30 min intervals into the fourth ventricle of rats or rabbits. After 4 h the nuclei from neurones, astrocytes, and other glial cells were isolated and RNA extracted. Investigations were performed in order to establish optimum conditions for RNA extraction from this particular material.

The sedimentation patterns obtained in sucrose gradients were similar to those of nuclear RNA from other mammalian tissues and showed the presence of RNA species with high specific activities in the region of the gradient between 10S and 16S and above 28S. All three types of nuclei contained a 45S and a 38S RNA. Moreover, a 32S component could be identified in astrocytic nuclei, a 35S fraction in neuronal nuclei, and both a 32S and 35S RNA in nuclei from glial cells. The nuclei from the various cell types also differ with respect to the rate of incorporation of the label into the nuclear RNA, being four times higher in astrocytic and neuronal nuclei than in those derived from the other glial cells.
GLYCOPROTEIN METABOLISM IN DEVELOPING MOUSE BRAIN1
Authors: Dutton G. R. , Barondes S. H.
Published: October 2006

—Incorporation of [14C]fucose or [14C]glucosamine into the glycoproteins of developing mouse brain was studied using polyacrylamide gel electrophoresis. Between 1 and 10 days after birth two fractions of soluble glycoproteins were extensively labelled, but by 15 days after birth incorporation into these fractions was no longer prominent. These glycoproteins have apparent molecular weights in the range of 150,000‐250,000, as estimated by the electrophoretic procedure. The more rapidly migrating fraction has a half‐life of about 1 week whereas the other is far more stable.
TOPOGRAPHICAL AND SUBCELLULAR LOCALIZATION OF CHOLINE ACETYLTRANSFERASE IN RAT HIPPOCAMPAL REGION
Authors: Fonnum F.
Published: October 2006

—Choline acetyltransferase (ChAc) was localized in discrete layers in hippocampus regio superior and in area dentata. The highest activity in hippocampus was found in a narrow infrapyramidal zone, but high activities were also observed in the rest of stratum oriens and in stratum pyramidale. In area dentata the highest activities were found in a narrow supragranular zone and in hilus fasciae dentatae. The localization corresponded very closely to that of acetylcholinesterase. The main part of ChAc activity was confined to the synaptosome fraction. The results are compatible with the view that pyramidal and granular cells are excited by cholinergic boutons, mainly located on the basal or apical dendrites near the somata.
[U‐14C]GLUCOSE METABOLISM OF THE PERFUSED CAT BRAIN WITH BLOOD FLOW DISTURBANCES1
Authors: Watanabe S. , Oisuki S. , Mitsunobu K. , Sannomiya T. , Okumura N.
Published: October 2006

—In order to study changes of the glycolytic‐respiratory system and amino acid metabolism associated with blood flow disturbance, the cat brain perfusion was conducted with artificial blood containing [U‐14C]glucose and the results were compared with those of standard perfusion keeping the cerebral blood flow at constant rate. The findings of the present study are briefly summarized:

(1) In blood flow disturbance there was observed an accumulation of lactate just as seen in the low functional state observable in the standard perfusion. However the increase in relative specific activity of lactate was not so marked as the rise in cerebral lactate content, and this indicates that there is an increase of lactate production from substrates other than glucose as well as an increase of net flow of glucose carbon to lactate.

(2) In blood flow disturbance relative specific activities of glutamate, aspartate, glutamine and respiratory CO2 were decreased as compared with those in the brain of high functional state. The relative specific activity of GABA in the reduced blood flow brain was at the same level as that of the brain at high functional state and it was higher than the relative specific activity of glutamate.

(3) The relative specific activity and content of alanine were increased in the low function brain with standard perfusion.
SUBCELLULAR DISTRIBUTION OF RADIOACTIVITY IN NEURONAL AND GLIAL‐ENRICHED FRACTIONS AFTER INCORPORATION OF [3H]LEUCINE IN VIVO AND IN VITRO
Authors: Hamberger A. , Blomstrand C. , Yanagihara T.
Published: October 2006

Abstract— The distribution of protein‐bound radioactivity among subcellular organelles of cerebral cortex was followed after intravenous administration of [3H]leucine and after incubation of brain slices in the presence of [3H]leucine. Neuronal and glial cell‐enriched fractions were prepared by discontinuous sucroseFicol1 gradient centrifugation of cerebral cortex cell suspensions. Subcellular fractions were obtained from each of the cell prepara‐ tions and the protein‐bound radioactivity determined after in uiuo and in vitro incorporation of [3H]leucine. The unfractionated neuronal material had a considerably higher level of protein‐bound radioactivity than the glial material. The most marked neuronal‐glial dif‐ ferences were observed in microsomes and soluble proteins, while the radioactive labelling of the nuclear and mitochondria1 fractions was similar for the two cell types.
THE OCCURRENCE OF TWO MYELIN BASIC PROTEINS IN THE CENTRAL NERVOUS SYSTEM OF RODENTS IN THE SUBORDERS MYOMORPHA AND SCIUROMORPHA
Authors: Martenson R. E. , Deibler Gladys E. , Kies Marian W.
Published: October 2006

Abstract—

Extracts containing myelin basic proteins have been prepared from CNS tissue of representatives of the three suborders of Rodentia—Myomorpha, Hystricomorpha and Sciuro‐morpha. Analyses of the extracts by electrophoresis at low pH showed that one type (L) of myelin basic protein is present in the CNS of all of the rodents examined (rat, mouse, hamster, guinea pig, chinchilla, prairie dog, woodchuck and squirrel). This protein is comparable in molecular size and charge to the CNS myelin basic proteins found in several other mammalian orders. In the CNS of the myomorphs (rat, mouse, hamster) and sciuro‐morphs (prairie dog, woodchuck, squirrel) there is an additional type (S) of myelin basic protein of higher cathodic mobility and smaller molecular size. This additional protein is absent from the CNS of the hystricomorphs (guinea pig, chinchilla). These findings indicate that the presence of two myelin basic proteins originally reported in the CNS of the inbred rat is not an anomaly of inbreeding. These data further suggest that the presence of a single L‐type CNS myelin basic protein might be a general characteristic of hystricomorphs, while the presence of both L‐ and S‐type CNS myelin basic proteins might be a general characteristic of the myomorphs and sciuromorphs.

Analyses by electrophoresis at low pH failed to reveal differences in mobility among either the L‐type or the S‐type CNS myelin basic proteins of the different species. In contrast, when electrophoresis was carried out cathodically at high pH, species‐related differences in mobility were observed among the L‐ and S‐type CNS myelin basic proteins.
STIMULATION OF BRAIN SEROTONIN SYNTHESIS BY DIBUTYRYL‐CYCLIC AMP IN RATS
Authors: Tagliamonte A. , Tagliamonte P. , Forn J. , Perez‐Cruet J. , Krishna G. , Gessa G. L.
Published: October 2006

Cyclic AMP and dibutyryl‐cyclic AMP, a derivative of cyclic AMP resistant to phosphodiesterase inactivation, were injected into the lateral ventricles of rats. These nucleotides did not change the level of brain 5‐HT but increased the brain level of its principal metabolite, 5‐hydroxyindoleacetic acid. Cyclic AMP was less potent than dibutyryl‐cyclic AMP. Butyrate and 5′‐AMP were inactive. The effect of dibutyryl cyclic AMP on 5‐HT metabolism was studied both in vivo and in vitro. The rate of synthesis of 5‐HT was measured by the rate of accumulation of 5‐hydroxyindoleacetic acid after the transport of this acid out of the brain was blocked with probenecid. The rate of synthesis of brain 5‐HT increased from 0‐38 μg/g/h in control rats to 0‐65 μg/g/h after dibutyryl‐cyclic AMP. In addition cyclic AMP and dibutyryl‐cyclic AMP markedly increased brain tryptophan, while AMP was inactive. Since brain tryptophan hydroxylase has a Km for its substrate that is much higher than the concentrations of tryptophan normally present in the brain, it is likely that the increase in the rate of synthesis of brain 5‐HT is secondary to the cyclic AMP induced increase in the levels of brain tryptophan. In vitro studies revealed that dibutyryl‐cyclic AMP increased the uptake of radioactive labelled tryptophan into slices of rat brain stem and the formation of 5‐HT and 5‐hydroxyindoleacetic acid.
PITFALLS IN THE USE OF RAPID FREEZING FOR STOPPING BRAIN AND SPINAL CORD METABOLISM IN RAT AND MOUSE
Authors: Swaab D. F.
Published: October 2006

The rate at which the metabolism is stopped by means of freezing in Freon‐12 (–150°C) was studied in various areas of the rat and mouse CNS, using changes in temperature and levels of glucose and lactate as parameters for this rate. The rat cerebral cortex was frozen after 0.5 min while the hypothalamus reached 0°C after more than 1.5 min. The skin on the skull was found to be the most important temperature isolator for the cortex. Substrate levels can be studied in this area only if this piece of skin is removed previously.

In the mouse, the cerebral cortex was frozen after 6 s, the hypothalamus after 0.5 min. The lumbar level of the mouse spinal cord was frozen after 15 s, the cervical level only after 47 s. Liquid nitrogen alone cooled the mouse cerebral cortex at least as fast as did Freon at its melting point. A gradual decrease from dorsal to ventral was observed in the glucose level of the molecular layer of the mouse cerebellum. The existence of a freezing front, moving slowly from dorsal to ventral, and its consequences for the measured levels of biologically labile substrates, are discussed.
INCORPORATION IN VIVO OF INTRACISTERNALLY INJECTED 33P1, INTO PHOSPHOLIPIDS OF RAT BRAIN1
Authors: Friedel R. O. , Schanberg S. M.
Published: October 2006

The incorporation in vivo of intracisternally injected 33Pi into individual phospholipids of rat brain was studied at intervals ranging froml min to 8 days after injection. At 1 min after injection there was significant incorporation of “Pi into PA and the phosphoino‐sitides, with the pattern of incorporation TPI > DPI > PA > PI. There was a 10‐min lag period before significant labelling of the remaining phospholipids. In general, the extent of incorporation measured during the first 8 days after injection paralleled the quantity of each phospholipid in the brain, except for the values of PA and the phosphoinositides which were all higher than would be predicted by this criterion and reached maximal incorporation sooner than the other phospholipids. The possible correlation of the high metabolic activities of PA and the phosphoinositides with neuronal function, as well as the importance of short‐term experiments in clarifying such relationships are discussed.
THE QUANTITATIVE HISTOCHEMISTRY OF ENZYMES OF THE PENTOSE PHOSPHATE PATHWAY IN THE CENTRAL NERVOUS SYSTEM OF THE RAT1
Authors: Kauffman F. C.
Published: October 2006

Abstract— Methods are presented for the measurement of the non‐oxidative enzymes of the pentose phosphate pathway in freeze‐dried samples of tissue weighing 2 μg or less. The activities of transketolase (EC 2.2.1.1), transaldolase (EC 2.2.1.2), ribosephosphate isomerase (EC 5.3.1.6), and ribulosephosphate epimerase (EC 5.1.3.1), together with glucose‐6‐phosphate dehydrogenase (EC 1.1.1.49) and 6‐phosphogluconate dehydrogenase (EC 1.1.1.44) have been measured in seven specific regions in the central nervous system of the rat. Michaelis constants and temperature coefficients of these enzymes were obtained on homogenates of whole rat brain. The entire enzymic complement of the pentose phosphate pathway was detected in each of the regions examined. The activities of the non‐oxidative enzymes and 6‐phosphogluconate dehydrogenase did not vary greatly among the different regions examined, whereas the activity of glucose‐6‐phosphate dehydrogenase varied in close correspondence with the lipid content of the various structures. The cellular, granular layer of the cerebellum was exceptional, since it exhibited at least three times more transaldolase activity than that observed in other structures, an observation suggesting an association of transaldolase with nerve cell bodies.
TIME AND TEMPERATURE DEPENDENT ACTIVATION OF PIG BRAIN GLUTAMINASE
Authors: Svenneby Gerd
Published: October 2006

Abstract— A time‐dependent activation of the tris‐HC1 enzyme form of pig brain glutaminase (EC 3.5.1.2, L‐glutamine amidohydrolase) by phosphate, phosphate‐borate and carboxylic acids is described. This time‐dependent activation increases with increased protein concentration and also with temperature. The sedimentation behaviour of the various activated enzyme preparations is described. The Arrhenius plot for the triq‐HC1 enzyme is curved, indicating a reversible equilibrium between two enzyme forms, whereas the plot obtained for the phosphate‐borate enzyme was a straight line. The apparent activationenergy has been determined.
GLYCOLYTIC SUBSTRATE UTILIZATION AND ENERGY CONSUMPTION IN THE CEREBRAL HEMISPHERES OF THE CHICK EMBRYO DURING THE PERIOD OF EEG DEVELOPMENT
Authors: Jongkind J. F. , Corner M. A. , Bruntink R.
Published: October 2006

Abstract— The glycolytic substrate utilization and energy consumption of chick embryo hemispheres aged 15 and 19 days, respectively, were studied by converting the heads into a closed system. After transforming the brain into a closed system by decapitation, spontaneous bio‐electrical potential changes, as indicated by EEG measurements, stayed normal in the hemispheres until at least 30 s after the procedure. Although the two developmental stages studied represented the start and the final phase of functional development, no changes in carbohydrate utilization and energy consumption were observed when comparing hemispheres of the two stages mentioned. The utilization of substrates other than glucose during embryological development is discussed. The disappearance of the EEG is not related to the overall depletion of high energy phosphates in the hemispheres since ATP is still present at nearly its original level after 2 min of ischaemia, despite the low level of P‐creatine occurring at 30 s after decapitation. A compartmentation of the major pools of P‐creatine and ATP is suggested.
DOPAMINE‐β‐HYDROXYLASE IN THE RAT BRAIN: DEVELOPMENTAL CHARACTERISTICS
Authors: Coyle J. T. , Axelrod J.
Published: October 2006

Abstract— A sensitive and specific assay for dopamine‐8‐hydroxylase (DBH) in the rat brain has been developed. The enzyme in the brain has requirements for cofactors and affinity for substrate similar to DBH in the adrenal medulla. DBH activity was demonstrable in the brain of the fetal rat at 15 days of gestation; there was an increase in DBH activity with maturation that preceded and paralleled the rise in levels of endogenous norepinephrine until 3 weeks after birth. There was a shift in the distribution of total DBH activity from the caudal to the rostral regions of the brain during development. In the adult brain, DBH was highly localized in the nerve terminals. Between 17 days of gestation and adult‐hood, there was 2300‐fold increase in the DBH activity that sedimented with sheared‐off nerve terminals.
IMMUNOHISTOCHEMICAL STUDIES OF S‐100 PROTEIN DURING POSTNATAL ONTOGENESIS OF THE BRAIN OF TWO STRAINS OF RATS
Authors: Sviridov S. M. , Korochkin L. I. , Ivanov V. N. , Maletskaya E. I. , Bakhtina T. K.
Published: October 2006

Abstract— We have studied the dynamics of the appearance of cells reacting positively with anti‐S‐100 protein antiserum, during postnatal neurocytogenesis in the brain of rats of two strains differing in their susceptibility to sound stimuli. The postnatal time of appearance of cells reacting positively with anti‐S‐100 protein antiserum was somewhat later in rats susceptible to sound‐induced seizures than in sound‐resistant rats. These differences concerned mainly the cerebral cortex of 12‐day‐old rats. By day 21 of postnatal life these differences had disappeared. In subcortical structures of the brain, S‐100 protein was first found on the 4th to the 5th day of life and the rate of appearance of cells containing this protein was similar in the two strains.
IONS AND THE TRANSPORT OF GAMMA‐AMINOBUTYRIC ACID BY SYNAPTOSOMES
Authors: Martin D. L. , Smith A. A.
Published: October 2006

Abstract— The initial rate of uptake of [2,3‐3H]gamma‐aminobutyric acid by rat brain synaptosomes was studied under incubation conditions in which GABA metabolism was minimal. The presence of both sodium and potassium in the incubation medium was essential for sustained uptake. Uptake proceeded for a short period of time in the absence of potassium and then ceased. No uptake was observed when sodium chloride was completely replaced with sucrose or choline chloride. The sodium‐dependence curve for GABA uptake was markedly sigmoid. The sigmoid character of the curve was not attributable to a lag phase in uptake at low sodium concentrations. Calcium strongly stimulated the initial rate of uptake at low sodium concentrations but had little effect at sodium concentrations above 100 mm and was not able to support uptake in the absence of sodium. The sigmoid character of thesodium‐dependence curve was completely eliminated by 20 mm calcium ion. Magnesium and phosphate had little effect on the initial rate of GABA uptake.
Isolation of glycosaminoglycans and variation with age in the feline brain
Authors: Young I. J. , Clistod J. T.
Published: October 2006

Many laboratories have reported the presence of glycosaminoglycans (GAG) in the brains of a variety of species, including monkey, man, cat, pig, rabbit, sheep, rat and chicken (Chandrasekaran and Bachhawat, 1969; Clausen and Hansen, 1963; Clausen and Rosenkast, 1962; Custod and Young, 1968; Margolis, 1967; Onodera, Hirona, Horiuchi and Kashimura, 1966; Saigo and Egami, 1970; Singh and Bachhawat, 1965, 1968; Singh, Chandrasekaran, Cherian and Bachhawat, 1969). Because of the interest of our laboratory in the GAG of the cat brain (Custod and Young, 1968; Young, 1963), we initiated the present studies to quantify these various brain polysaccharides and to investigate their changes as a function of postnatal age.
ORNITHINE DECARBOXYLASE ACTIVITY IN DEVELOPING RAT BRAIN1
Authors: Anderson T. R. , Schanberg S. M.
Published: October 2006

—Total ornithine decarboxylase (ODC) (EC 4.1.1.17) activity per rat brain was elevated markedly from 14 days after conception to 12 days postnatum. ODC activity in the brainstem was very low and changed little during postnatal development. Activity in the cerebral hemispheres declined from a high level at birth to the low adult level by 8 days postnatum. Conversely activity in the cerebellum increased markedly from 3 days until 11 days postnatum, then suddenly decreased. Hence, the periods of greatest ODC activity paralleled those of maximal cell proliferation in each brain region. During perinatal brain development ODC activity changed considerably; it declined at about one day prior to term, and then increased rapidly to its highest level of activity at 4 h postnatum. Premature birth by caesarian section or lack of maternal care and nutrition did not affect this early postnatal response. The postnatal burst in ODC activity appears to be unique for brain tissue, since this response did not occur in heart, skeletal muscle or liver.

Data from studies in which portions of fractions characterized by high or low enzymatic activity, respectively, were mixed or in which the supernatant enzyme fraction was dialysed are not consistent with the presence of direct inhibitors or activators of the enzyme. In addition, administration of cycloheximide to newborn rats abolished the 4‐h postnatal burst in ODC activity. Our results suggest that the increase in ODC activity reflects enzyme synthesis de novo.
EFFECTS OF 5,6‐DIHYDROXYTRYPTAMINE ON MONOAMINERGIC NEURONES IN THE CENTRAL NERVOUS SYSTEM OF THE RAT
Authors: Baumgarten H. G. , Evetts K. D. , Holman R. B. , Iversen L. L. , Vogt Marthe , Wilson Gay
Published: October 2006

—The injection of 50 μg of 5,6‐dihydroxytryptamine (5,6‐HT) into a lateral ventricle of the rat depleted the spinal cord and various regions of the brain of indoleamines (presumably 5‐HT) and 5‐hydroxyindole acetic acid. The concentrations of 5‐HT were measured by two different methods: the formation of a fluorescent derivative with o‐phthalaldehyde, and the native fluorescence in hydrochloric acid. When the results of both methods were compared on the pons and medulla 4 days after injecting 5,6‐HT, the loss in indoleamine appeared to be greater when o‐phthalaldehyde was used. This suggests that the two methods may be measuring different compounds. According to both methods, the loss of 5‐HT persisted for several days after the injection of 5,6‐HT, but by 2 months 5‐HT concentrations (measured only by the native fluorescence procedure), had recovered to near‐normal values. The depletion of 5‐HT was most pronounced in regions adjacent to the ventricular system and in the spinal cord. Initially, caudate and septum were more affected on the side of the injection, and later showed some permanent atrophy. The injection of up to 50 μg of 5,6‐HT did not lead to any significant loss of noradrenaline or dopamine from the brain, or to any reduction in the activity of the enzyme tyrosine hydroxylase. The drug was a potent inhibitor of the uptake of [3H]5‐HT by brain slices, but was less effective in inhibiting catecholamine uptake systems. These observations suggest a preferential action on tryptaminergic neurones. Larger doses of 5,6‐HT caused a loss of catecholamines and tyrosine hydroxylase from the brain, and were severely toxic.
EFFECTS OF IMIDAZOLEACETIC ACID ON BRAIN AMINO ACIDS AND BODY TEMPERATURE IN MICE1
Authors: Tunnicliff G. , Wein J. , Roberts E.
Published: October 2006

Free amino acids have been studied in the brains of fasted mice (18 h) injected intraperitoneally with a 3 mmol/kg dose of imidazole‐4‐acetic acid (IMA). Groups of mice were killed by cervical dislocation and their brains were removed before injection or at 5, 15, 30, 60, 90 and 120 min after injection and treated immediately with perchloric acid. Amino acid analyses were performed on the perchlorate extracts. Of the 16 amino acids evaluated quantitatively, only glutamic acid and glutamine showed progressive changes during the period of observation, the glutamic acid falling and glutamine levels rising. Serine and threonine levels were increased significantly above the control values from 30 min after the injection to the end of the experiment. Rectal temperatures (measured with a thermistor probe) after injection of IMA showed a progressive reduction from the control levels throughout the period of observation. An essentially linear correlation was noted between the decreases in body temperature and the differences between the glutamic acid and glutamine values for the first 90 min post‐injection. Our data suggest that IMA affects mechanisms of temperature regulation, possibly in the hypothalamus, and that, among other processes, the activities of glutaminase and of serine and threonine dehydratases in brain might be reduced when brain temperatures fall.
EVIDENCE FOR THE SYNTHESIS AND STORAGE OF 5‐HYDROXYTRYPTAMINE IN TWO SEPARATE POOLS IN THE BRAIN
Authors: Shields P. J. , Eccleston D.
Published: October 2006

Abstract— Evidence is presented to support the hypothesis that 5‐hydroxytryptamine (5‐HT) in the rat brain is synthesized by two separate pathways and stored in two or more compartments. Lysergic acid diethylamide in doses down to 50 μg/kg was shown to reduce the formation of 5‐[3H]HT from [3H]tryptophan in the presence of a monoamine oxidase inhibitor, although the total rate of accumulation of 5‐HT was unchanged. Conversely, adrenalectomy was found to increase the total synthesis of 5‐HT measured in the same way, although the amount of 5‐[3H]HT formed suggested that there was no increase in the synthesis of the amine. In a third experiment it was found that electrical stimulation of 5‐HT‐containing nerves following labelling of 5‐HT stores with [3H]tryptophan led to a biphasic disappearance of 5‐[3H]HT. It is suggested that the method of measuring 5‐HT synthesis by measuring 5‐[3H]HT formed from[3H]tryptophan in the presence of a monoamine oxidase inhibitor may be a way of selectively measuring the turnover of the functional pool of 5‐HT.
BASE‐EXCHANGE ENZYMIC SYSTEM FOR THE SYNTHESIS OF PHOSPHOLIPIDS IN NEURONAL AND GLIAL CELLS AND THEIR SUBFRACTIONS: A POSSIBLE MARKER FOR NEURONAL MEMBRANES1
Authors: Goracci G. , Blomstrand C. , Arienti G. , Hamberger A. , Porcellati G.
Published: October 2006

Abstract— The calcium‐dependent incorporation of L‐[3‐14C]serine and [1,2−14C]ethanolamine into the phospholipid of isolated neuronal and glial cells from rabbit brain was studied, and the distribution of the enzymic system among the correspondent subfractions was examined. The neuronal cell‐enriched fraction was found to possess a much higher rate of exchange of both bases than the glial cell‐enriched fraction. Among the sub‐fractions isolated from the neuronal and glial cells, those corresponding to neuronal plasma membranes and microsomes showed a noticeably higher exchange of serine and ethanolamine compared to the corresponding subfractions from glia. Neuronal/glial ratios of about 6–8 were found for the exchange activity in both plasma membrane‐enriched fraction and in microsomes. Synaptosomes and synaptosomal subfractions contained low activities. It is concluded that the calcium‐dependent enzymic system for the exchange of serine, ethanolamine and other nitrogenous bases with endogenous phospholipid is concentrated mostly in the neuronal perikaryal membranes, and could be used as a neuronal marker.
Isolation of hypoxanthine from calf brain
Authors: Mori A. , Ohkusu H. , Kohsaka M. , Kurono M.
Published: October 2006

Except for the crystalline deposits of hypoxanthine found in skeletal muscle of patients with congenital xanthine oxidase deficiency (xanthinuria) there are few reports concerning oxypurines in the mammalian tissues (Parker, Snedden and Watts, 1969, 1970). Since it is difficult to separate hypoxanthine from xanthine in biological fluids (Simmonds and Wilson, 1967), the distribution of hypoxanthine in mammalian tissues is not known in detail.

This paper shows that cubic or rod crystals of C5H4ON4are easily isolated from calf brain by column chromatography with ion exchange resin Amberlite CG120 and their identity with hypoxanthine was shown by means of nuclear magnetic resonance and mass Spectrometry.
MYELIN SUBFRACTIONS IN DEVELOPING RAT BRAIN: CHARACTERIZATION AND SULPHATIDE METABOLISM
Authors: Benjamins Joyce A. , Miller Karen , McKhann G. M.
Published: October 2006

Centrifugation of isolated myelin on discontinuous sucrose gradients resulted in a separation into three bands and a pellet. The three bands were morphologically identical to myelin, whereas the pellet consisted primarily of vesicular membranes. These four fractions differed from one another in their lipid‐to‐protein ratios and in molar ratios of cholesterol:phospholipid:galactolipid. All of the fractions contained proteins typical of myelin, although the proportions of the proteins varied, with the pellet being the lowest in basic protein and proteolipid protein. High activity of 2′,3′‐cyclic nucleotidase and low activity of cerebroside sulphotransferase further distinguished these fractions from the microsomal fraction. Distribution of radioactive sulphatide in the subfractions at 15 min after intracranial injection of radioactive sulphate indicated that newly‐labelled sulphatide first appeared in the lipid‐poor fractions, followed by the lipid‐rich fractions; results of pulse‐chase experiments also suggested this relationship. Several days or weeks after the injection of radioactive sulphate, most of the radioactive sulphatide was in the lipid‐rich fractions.
AXONAL TRANSPORT OF RADIOACTIVITY IN THE GOLDFISH OPTIC SYSTEM FOLLOWING INTRAOCULAR INJECTION OF LABELLED RNA PRECURSORS
Authors: Ingoglia N. A. , Grafstein B. , McEwen B. S. , McQuarrie I. G.
Published: October 2006

After injection of the tritiated RNA precursors [3H]guanosine, [3H]uridine or [3H]orotic acid into the eye of goldfish, labelled TCA‐soluble material and RNA appeared to be axonally transported to the contralateral optic tectum. From the time courses of arrival in the tectum,‘average’rates of transport of 6 mm/day for the soluble material and 1·7 mm/day for the RNA were calculated. If the optic nerve was cut after the transported material had arrived in the tectum, about 60 per cent of the TCA‐soluble material disappeared by 7 days after the cut, but almost none of the RNA. After a further 8‐ to 13‐day period, the TCA‐soluble material had declined by a further 50 per cent from the 7‐day value, but the RNA by only 20 per cent. Thus, relatively little RNA was lost when the optic axons degenerated, an observation which suggested that the RNA might be extra‐axonal. However, if the optic nerve was crushed before the arrival of the transported material, RNA did not appear in the tectum until the regenerating optic nerve fibres arrived. Therefore, the presence of RNA must be dependent on intact nerve fibres. Moreover, in the earliest stages of regeneration the proportion of transported RNA to TCA‐soluble material was considerably higher than normal, suggesting that the regenerating fibres arrived in the tectum already carrying RNA. This implies that the RNA itself was transported in the optic fibres.
RELATIONSHIP BETWEEN THE RATE OF AXOPLASMIC TRANSPORT AND SUBCELLULAR DISTRIBUTION OF ENZYMES INVOLVED IN THE SYNTHESIS OF NOREPINEPHRINE
Authors: Oesch F. , Otten U. , Thoenen H.
Published: October 2006

The net rate of proximo‐distal transport of tyrosine hydroxylase, dopamine β‐hydroxylase, DOPA decarboxylase and choline acetyltransferase was determined by measuring the accumulation of these enzymes proximal to a ligature of the rat sciatic nerve. The rate of accumulation was constant for at least 12 h. For the enzymes involved in the biosynthesis of norepinephrine the rate of transport was correlated to their subcellular distribution and a close correlation between these two parameters was found. Dopamine β‐hydroxylase, an enzyme mainly localized in the particulate fraction of the sciatic nerve, showed the fastest rate of transport (1·94 mm/h) whereas DOPA decarboxylase, exclusively located in the high‐speed supernatant fluid, gave the slowest (0·63 mm/h) rate of transport. Tyrosine hydroxylase, predominantly located in the non‐particulate fraction of the sciatic nerve was transported much slower (0·75 mm/h) than dopamine β‐hydroxylase but still significantly (P < 0.005) faster than DOPA decarboxylase. The subcellular distribution of dopamine β‐hydroxylase in ganglia did not differ significantly (0·45 > P > 0·40) from that in the sciatic nerve, but in nerve endings a greater proportion of dopamine β‐hydroxylase was localized in particulate fractions. Tyrosine hydroxylase and DOPA decarboxylase were found exclusively in the non‐particulate fractions of ganglia. In the nerve endings of the effector organs a small but consistent portion of tyrosine hydroxylase was found in particulate fractions, whereas DOPA decarboxylase was exclusively localized in the high‐speed supernatant fluid.
EVIDENCE THAT THE MAJOR PROTEIN IN RAT SCIATIC NERVE MYELIN IS A GLYCOPROTEIN
Authors: Everly J. L. , Brady R. O. , Quarles R. H.
Published: October 2006

Evidence is presented that the major protein of rat sciatic nerve myelin is a glycoprotein. When myelin proteins were separated by polyacrylamide gel electrophoresis, the major band which was stained with amido black–Coomassie blue was also stained with periodic acid‐Schiff reagents for carbohydrate. Radioactive labelling of myelin in vivo with [3H]leucine and [14C]fucose, followed by electrophoresis of the proteins, indicated that with both isotopes the major labelled peak corresponded to the major stained band. In addition, a second smaller peak of [14C]fucose migrated ahead of the major peak. Delipidated myelin contained galactose, mannose, fucose and sialic acid.
TURNOVER OF PHOSPHATIDYLCHOLINE IN CELL MEMBRANES OF ADULT RAT BRAIN1
Authors: Pasquini J. M. , Krawiec L. , Soto E. F.
Published: October 2006

—Incorporation of radioactive choline into subcellular fractions of adult rat brains, after intracranial injection of the precursor, was studied at different times. Maximum labelling of phosphatidylcholine occurred at 5 h in all fractions, the highest specific radio‐activity being found in mitochondria. The specific radioactivity diminished rapidly for a few hours after the peak of maximum incorporation and continued to decrease thereafter at a much slower rate. The type of decay curve found in all fractions except myelin, indicated the possible presence of two populations of phosphatidylcholine with quite different turnover rates. The significance of these findings is discussed.
ACCUMULATION OF HISTIDINE, 3‐METHYLHISTIDINE, AND HOMOCARNOSINE IN THE BRAINS OF PROTEIN‐CALORIE DEFICIENT MONKEYS1
Authors: Enwonwu C. O. , Worthington Bonnie S.
Published: October 2006

Abstract— Seventeen monkeys (M. nemestrina and M. fascicularis) aged 10 months to about 5 yr were divided into two groups and fed either an adequate protein diet (20% casein) or a low‐protein diet (2% casein). The diets were supplied to the animals in restricted amount (200 g/animal in two daily rations). In one experiment, the malnourished animals were initially fed a diet containiing 8 per cent protein and the protein content of the diet was gradually reduced over a period of 9 months, to 2 per cent. After about 3 months on the 2 per cent protein diet, the malnourished monkeys showed growth failure, severe anorexia, peri‐ocular oedema, tremors of the head and limbs, atrophy of several visceral organs, fatty liver, hypoalbuminaemia, and depressed serum levels of many essential amino acids with an elevation of the ratio of non‐essential to essential amino acids. These features are consistent with protein‐calorie malnutrition. Examination of the brains revealed significant alterations in the levels of glycerophosphoethanolamine (—40 per cent), glutamic acid (—25 per cent), histidine (+230 per cent), homocamosine (+185 per cent), 3‐methyl‐histidine (+147 per cent), lysine (+55 per cent), phenylalanine (+33 per cent) and tyrosine (+26 per cent) in comparison to findings on the well‐fed monkeys. The possible implications of elevated cerebral contents of homocarnosine in malnourished monkeys are discussed in the light of several reported human cases in whom neurological disorders are associated with increased histidine‐containing dipeptides in the brain, CSF, blood and urine.
COMPARATIVE EFFECTS OF HYPOTHYROIDISM, HYPERTHYROIDISM AND UNDERNUTRITION ON THE PROTEIN AND NUCLEIC ACID CONTENTS OF THE CEREBELLUM IN THE YOUNG RAT
Authors: Gourdon J. , Clos J. , Coste C. , Dainat J. , Legrand J.
Published: October 2006

Abstract— The effects of hypothyroidism, hyperthyroidism and undernutrition on the development of the protein and nucleic acid contents of the cerebellum were studied in young rats ranging in age from 6 to 35 days. Foetal and neonatal propylthiouracil treatment caused a delayed cell multiplication in the organ but this delay had disappeared at 35 days. As early as the age of 10 days, the total cerebellar RNA and protein contents in these hypothyroid animals were lower than in the normal animals but the mean cellular contents of RNA and protein were not lowered before the age of 21 days. Slight neonatal hyperthyroidism, induced by the daily injection of a relatively small dose of thyroxine, produced an accelerated cell multiplication during the first postnatal week and afterwards a delay in cell proliferation. In the hyperthyroid animals, the mean cellular protein content, initially higher than normal, tended to be lower at 35 days. At this age, the cell number had nearly returned to normal. Undernutrition directly led to a reduced cell proliferation and the reduced cell number still persisted at 35 days. At first, the cells were on the average larger than normal, but the effect on the mean RNA and protein contents per cell was not persistent in the underfed animals.

This study correlates the degree of neonatal hyperthyroidism with the further development of the cell population of the cerebellum and emphasizes the importance of the events which take place just after birth in the cerebellum submitted to an excess or a deficiency of thyroid hormone. In addition, the results are discussed in relation to data concerning the morphogenetic action of thyroid and of underfeeding on the cerebellum.
THE SUBCELLULAR LOCALIZATION OF CYTIDINE 5′‐MONOPHOSPHO‐N‐ACETYLNEURAMINIC ACID SYNTHETASE IN CALF BRAIN
Authors: Van den Eijnden D. H.
Published: October 2006

Abstract— The subcellular distribution of cytidine 5′‐monophospho‐N‐acetylneuraminic acid synthetase, which is a key enzyme involved in the biosynthesis of sialo‐glycoproteins and gangliosides, was studied in the frontal grey cortex and the corpus callosum of the calf brain. It appeared that the enzyme was highly concentrated in nuclear fractions, which were shown to be relatively pure as evaluated from morphological, enzymic and chemical data. The possibility that the nuclear localization of the enzyme was due to an artifact, as the result of adsorption onto the nuclear membrane or absorption into the nucleus during the homogenization of the tissue, was ruled out completely and so it appeared that cytidine 5′‐monophospho‐N‐acetylneuraminic acid synthetase, at least for the greater part, is a true nuclear enzyme. The subnuclear localization of the enzyme was shown to be in the nuclear sap. Both neuronal and glial cell nuclei contained the enzyme, which makes it very likely that biosynthesis of sialo‐glycoproteins and/or gangliosides occurs in neurons as well as in glial cells. The significance of the nuclear localization of the enzyme for the biosynthesis of sialic acid containing macromolecules and the possible regulatory role played by the nucleus in this process are discussed.
CHANGES IN LIPID CONCENTRATIONS AND FATTY ACID COMPOSITIONS IN RAT CEREBRUM DURING MATURATION
Authors: Alling C. , Karlsson I.
Published: October 2006

Abstract— Rat cerebrum was analysed at 20 different ages from birth to 45 days of age, for its concentration of protein, cholesterol, cerebrosides, phospholipids and gangliosides, and for the concentration of fatty acids of the linoleic and linolenic acid series. The fatty acid patterns of choline phosphoglycerides and ethanolamine phosphoglycerides were determined at the same ages. Phases of rapid accretion were found for protein, phospholipids, gangliosides and cholesterol. The accretion of the fatty acids of the linoleic acid series ceased at 20 days of age, while that of the fatty acids of the linolenic acid series continued. The fatty acid composition of the phosphoglycerides changed during the maturation of rat cerebrum and these changes consisted of chain elongation, increased unsaturation and variation in the pattern of the polyenoic acids. These changes varied irregularly with age and each developmental stage had characteristic fatty acid patterns of choline and ethanolamine phosphoglycerides.
ENZYMES OF THE γ‐GLUTAMYL CYCLE IN THE CHOROID PLEXUS AND BRAIN
Authors: Okonkwo P. Obiekwe , Orlowski Marian , Green J. P.
Published: October 2006

—The presence of enzymes of the γ‐glutamyl cycle in the bovine and rabbit brain and choroid plexus is described. The activities of γ‐glutamyl transpeptidase, γ‐glutamyl cyclotransferase and γ‐glutamyl‐cysteine synthetase in the choroid plexus were found to be higher than in the brain. The activity of γ‐glutamyl transpeptidase in the choroid plexus was many times higher than the activity of the other enzymes. Brain and choroid plexus γ‐glutamyl transpeptidase were activated by Na+ and K+. Both brain and choroid plexus showed only a very limited capacity to metabolize [14C]5‐oxoproline to 14CO2.
RNA METABOLISM IN RABBIT BRAIN: STUDY WITH NEURON‐GLIA AND SUBCELLULAR FRACTIONS1
Authors: Yanagihara T.
Published: October 2006

—Uridine incorporation into RNA of rabbit brain was studied by using an in vitro system for incubation of brain slices for up to 180 min. Neuron‐enriched and glia‐enriched fractions were prepared by ficoll density gradient centrifugation, and various subcellular fractions were prepared by sucrose density gradient centrifugation. Although the difference was not as great as in the case of l‐leucine incorporation into protein, the neuron‐enriched fraction consistently showed a higher specific radioactivity than the glia‐enriched fraction. The specific radioactivity of the nuclei increased promptly and remained high at 180 min; the increase in the microsomes was gradual. Comparison of these data suggests that both neuron‐enriched and glia‐enriched fractions retain high radioactivities in their nuclei at 180 min when a considerable portion of the ribosomal RNA in these fractions is not labeled. The sharp diffusion gradient of nucleotides is discussed in relation to the acid‐soluble radioactivity.
THE EFFECT OF PHOSPHOLIPASES ON THE ACTIVE UPTAKE OF NOREPINEPHRINE BY SYNAPTOSOMES ISOLATED FROM THE CEREBRAL CORTEX OF GUINEA PIG1
Authors: Sun A. Y.
Published: October 2006

—Phospholipase A (EC 3.1.1.4) and phospholipase C (EC 3.1.4.3) were used for studying the role of phospholipid of synaptosomal membrane on norepinephrine uptake activity. Synaptosomes were isolated from cerebral cortex of guinea pigs and treated with phospholipase A or phospholipase C before the uptake experiments. Treatment of synaptosomes with phospholipase A has resulted in severe inhibition of norepinephrine‐uptake. Under similar conditions, the activity of synaptosomal (Na + K)‐ATPase (EC 3.6.1.4) was also inhibited by phospholipase A treatment whereas the activity of synaptosomal acetylcholinesterase (EC 3.1.1.8) was not affected. On the other hand, the norepinephrine‐uptake was not influenced by phospholipase C treatment. The inhibition of norepinephrine‐uptake after phospholipase A treatment may be due to the liberation of lyso‐components of phospholipids since a low concentration of lysolecithin as well as other detergents (deoxycholate and sodium dodecyl sulphate) also inhibit the uptake activity. However, electron microscopic examination indicated that the synaptosomal particles still maintain their morphological features after phospholipase A treatment. It is possible that the active uptake of norepinephrine depends upon the fine arrangement of phospholipids present at the active sites of the synaptosomal membrane.
INFLUENCE OF HYPOXIA ON CEREBRAL ENERGY STATE IN RATS WITH PORTA‐CAVAL ANASTOMOSIS
Authors: Holmin T. , Siesjö B. K.
Published: October 2006

Abstract— In order to evaluate whether porta‐caval anastomosis, and the accompanying hyperammonemia, affect the balance between production and utilization of ATP in the brain, organic phosphates and carbohydrate substrates were measured in control and shunted rats exposed to hypoxia (arterial Po2 about 30 mm Hg). In the shunted animals the cortical ammonia content was about 2.5 times that measured in the controls, and there was a marked accumulation of glutamine. The intracellular lactate concentration was identical in the control and the shunted groups, and the pattern of change in carbohydrate substrates was similar. There were no significant differences in ATP, ADP or AMP between the groups but the shunted group showed a significantly lower phosphocreatine content. However, the fall in phosphocreatine in the shunted group could be related to a decrease in the sum of phosphocreatine and creatine. It is concluded that the shunting procedure does not disturb the balance between energy production and energy utilization in the brain.