bluuebunny/crossref_metadata_2025 huggingface dataset:
THE ORIGIN OF THE ACETYLCHOLINE RELEASED FROM THE SURFACE OF THE CORTEX
Authors: Chakrin L. W. , Marchbanks R. M. , Mitchell J. F. , Whittaker V. P.
Published: October 2006

—The specific radioactivity of acetylcholine liberated from the surface of the rabbit occipital cortex has been compared with that of the underlying cortical synaptosomal and vesicular acetylcholine at varying times after the administration of [N‐Me‐3H]choline. Choline was administered by diffusion from solutions placed in cups formed by Perspex cylinders applied to the surface of the cortex. Acetylcholine was collected by diffusion into these cups. The specific radioactivity of the acetylcholine declined progressively. The effect of stimulation of afferent cholinergic pathways was to cause a fall in the specific radioactivity of the released acetylcholine. However this was always higher than that of the synaptosomal or vesicular acetylcholine as represented by fractions P2 and D of the authors’fractionation scheme. It is concluded that acetylcholine released from the cortex must come from a store or stores more recently synthesized than the endogenous acetylcholine of these subcellular fractions.
MECHANISMS FOR THE EFFLUX OF [14C]DOPA AND [14C]DOPAMINE FROM THE CSF OF RHESUS MONKEYS
Authors: Shaywitz B. A. , Gormley W. T. , Arnold E. L. , Back K. C.
Published: October 2006

—Clearance of [14C]DOPA and [14C]dopamine from CSF was investigated in anaesthetized rhesus monkeys (M. Mulatta) subjected to ventriculocisternal perfusion. The efflux coefficients, kVE, at tracer concentrations (3–5 m) in the perfusate were 0.0487 ml/min and 0.0325 ml/min for [14C]DOPA and [14C]dopamine, respectively. Carrier DOPA (10 mm) in the perfusate decreased the efflux of [14C]DOPAsignificantly, but carrier dopamine had no appreciable effect on the clearance of [14C]dopamine. These findings suggest that DOPA is cleared from CSF in part by a saturable mechanism which may be located in the choroid plexus, whereas dopamine leaves the ventricular system by passive diffusion. Radioactivity in the caudate nucleus immediately adjacent to the perfused ventricle averaged 15.5 % and 12.6% of the radioactivity in the perfusates with [14C]DOPA or [14C]dopamine, respectively. These distribution percentages were similar to those found for various extracellular indicators after ventriculocisternal perfusion and may indicate that the efflux of intraventricularly‐administered exogenous DOPA and dopamine occurs in part through extracellular channels.
THE REGIONAL DISTRIBUTION OF CYTIDINE 5′‐MONOPHOSPHO‐N‐ACETYL‐NEURAMINIC ACID SYNTHETASE IN CALF BRAIN
Authors: Van Den Eijnden D. H. , Meems L. , Roukema P. A.
Published: October 2006

—The enzyme cytidine 5′‐monophospho‐N‐acetylneuraminic acid synthetase was studied in different parts of the calf brain. Characterization of partial purified enzyme preparations from cortical grey matter and corpus callosum by means of pH optima and Km values, showed the enzyme of grey and white brain areas to be identical. Unexpectedly the regional differences of the enzyme activities per g wet tissue and per mg protein were very slight. From the presence of the enzyme in pure white brain areas, which are known to be poor in neuronal perikarya, and the fact that the enzyme is localized in the cell nucleus, we concluded that cytidine 5′‐monophospho‐N‐acetylneuraminic acid is produced in glia cell nuclei and that it is very likely that biosynthesis of sialo‐glycoproteins and/or ganglio‐sides occurs within glia cells.

The enzyme activity per μmol DNA‐P is somewhat higher in grey than in white regions, indicating a slightly higher activity per neuronal than per glial nucleus.

The regional differences of lipid and protein‐bound sialic acid and RNA show a striking similarity and contrast to those of the enzyme. These differences are interpreted in terms of a differential content in neurons and glia cells.
SUBCELLULAR DISTRIBUTION OF PYRUVATE KINASE (EC 2.7.1.40) IN CEREBRAL CORTEX
Authors: Tamir H. , Kaufman H. , Rapport M. M.
Published: October 2006

—The subcellular distribution of pyruvate kinase (EC 2.7.1.40) in the cerebral cortex of the rat was studied. The enzyme, which had been previously reported in the cytoplasm, was found to be present in synaptosomal, microsomal and mitochondrial fractions as well. The activity of the enzyme in the synaptosomal fraction was localized predominantly in the synaptosomal membrane and was not dissociated by repeated washing or recentri‐fuging in a sucrose gradient. Some kinetic parameters of the membrane‐associated pyruvate kinase were measured.
MASS FRAGMENTOGRAPHIC ASSAY OF HOMOVANILLIC ACID IN BRAIN TISSUE1
Authors: Sjöquist Birgitta , Dailey J. , Sedvall G. , ÄNggård E.
Published: October 2006

Abstract— Available methods for the determination of homovanillic acid (HVA) are based on fluorimetric measurements. The present method uses gas chromatography‐mass spectrometry with the aid of deuterium labelled HVA methyl ester as a carrier and internal standard. Quantitation is achieved by comparing intensities of the molecular ion (= base peak) of the protium (H) and deuterium (D) forms of the methyl ester heptafluorobutyric derivatives of HVA. A standard curve is constructed by measuring mixtures of known amounts of protium and deuterium derivatives and plotting peak height ratios H/D on the ordinate and ratios of amounts H/D on the abscissa. Analysis of ten individual mouse brains gave a mean value of 1·36 nmole/g brain tissue with a standard deviation of ±9 per cent. Chlorpromazine elevates, whereas pargyline reduces the level of HVA in brain markedly. The described procedure offers advantages because of the greatly increased specificity and sensitivity permitting analyses in discrete brain areas.
METABOLISM OF TRITIUM‐LABELLED PYRIDOXINE AND PYRIDOXINE 5′‐PHOSPHATE IN THE CENTRAL NERVOUS SYSTEM1
Authors: Tiselius H.‐G.
Published: October 2006

Abstract— [3H]Pyridoxine and [3H]pyridoxine 5′‐phosphate have been injected into rats and mice. The uptake in brain tissue has been studied by comparing the concentrations of labelled compounds in serum, cerebrospinal fluid and brain tissue. Labelled pyridoxine passes rapidly into brain tissue, whereas the uptake of pyridoxine 5′‐phosphate occurs at a much slower rate.

Perchloric acid extracts of brain have been fractionated by ion‐exchange chromatography and the distribution of isotope between the different forms of the vitamin has been determined at different times after the administration. The time sequence of the metabolic transformation is: pyridoxine+→ pyridoxine 5′‐phosphate → pyridoxal 5′‐phosphate → pyridoxamine 5′‐phosphate. After the initial transformation period about 40 per cent of the isotope is recovered in each of the pyridoxal 5′‐phosphate and pyridoxamine 5′‐phosphate fractions.
EFFECT OF SCORPION VENOM, TITYUSTOXIN, ON THE RELEASE OF ACETYLCHOLINE FROM INCUBATED SLICES OF RAT BRAIN1
Authors: Gomez Marcus V. , Dai M. E. M. , Diniz C. R.
Published: October 2006

Abstract— Purified tityustoxin (TsTX) from the venom of the scorpion, Tityus serrulatus, when incubated in vitro with slices of rat cerebral cortex, increased the amount of free ace‐tylcholine (ACh) in the incubation medium and, simultaneously, reduced the amount of bound ACh in the slices. The effect was optimal at pH 7.4 and was dependent upon time of incubation, an energy source and the concentration of toxin. Tityustoxin increased the synthesis of ACh, but this effect seemed to be related to an increase in the release of ACh. The effect of the TsTX was independent of the concentration of K+ ion but was dependent on the presence of Na+ and Ca2+ in the incubation medium. Hexamethonium and hemicholinium reduced the effect of tityustoxin, but cocaine had no effect on the release of ACh stimulated by the TsTX. Tetrodotoxin blocked completely the stimulation caused by the tityustoxin. We suggest that probably both tityustoxin and tetrodotoxin exert different and antagonistic effects competing in the Na+ channels.
ACETYLCHOLINE SYNTHESIS FROM [2‐14C]PYRUVATE IN RAT STRIATAL SLICES
Authors: Lefresne P. , Guyenet P. , Glowinski J.
Published: October 2006

Abstract— Rat striatal slices were incubated with [2‐14C]pyruvate or [6‐14C]glucose as sole carbon source. The method devised to study the accumulation of labelled ACh in tissues and incubating medium in the presence or absence of eserine 200 μM derived from the previous studies of FONNUM (1969) and Hemsworth and Morris (1964). Total ACh was estimated by biological assay.

The specific activity of newly synthesized ACh was found to be equal to that of the precursors, even for short incubation times and low substrates concentrations. When slices were incubated with [2‐14C]pyruvate and eserine, the spontaneous release of ACh occurred at a constant rate, was not modified by the addition of 2 mM‐choline in the medium, and consisted only of newly synthesized transmitter.

The initial rate of ACh synthesis was found to be independent of choline concentration, but dependent on the [2‐14C]pyruvate concentration, and reached a maximal value corresponding to about 5 per cent of the measured striatal choline acetyltransferase activity.

The appearance of the so called ‘surplus ACh’ pool, obtained in the presence of eserine, could be detected only after 30 min and represented 26 per cent of the total tissue ACh content after 180 min of incubation.

In the absence of eserine, tissue ACh levels increased six‐fold in 80 min and then remained stable until the end of the incubation period (180 min), if sufficient substrate was provided. The maximal ACh accumulation in slices was independent of both excess of choline and [2‐14C]pyruvate.

The ‘ACh plateau’ represented the attainment of a new dynamic equilibrium, since ACh synthesis could still be stimulated by 30 mM‐K+. From these results, it was concluded that ACh synthesis is controlled by a negative feed‐back regulation.
Development of adrenergic neurons in uiuo: inhibition by ganglionic blockade
Authors: Black Ira B.
Published: October 2006

The Normal biochemical maturation of postsynaptic adrenergic neurons in mouse and rat superior cervical ganglion depends upon an intact preganglionic innervation (Black, Hendry and Iversen, 1971a, 1972; Thoenen, Saner and Keitler, 1972). In recent studies tyrosine hydroxylase, the rate‐limiting enzyme in norepinephrine biosynthesis (Levitt, Spector, Sjoerdsma and Udenfriend, 1965), with localization to adrenergic neurons in the ganglion (Black, Hendry and Iversen, 1971b), was used to monitor maturation of these cells. The developmental increase in tyrosine hydroxylase activity occurred simultaneously with the appearance of ganglionic synapses and was prevented by transection of the preganglionic nerve trunk (Black, Hendry and Iversen, 1971a). These observations suggest that presynaptic cholinergic nerve terminals regulate the biochemical development of postsynaptic neurons in the superior cervical ganglion. The mechanism(s) by which presynaptic cholinergic terminals regulate postsynaptic development has not been elucidated. Such trans‐synaptic regulation may be dependent on normal impulse transmission and/or may involve other unidentified, trophic factors. The results presented in the present communication suggest that normal development of ganglionic tyrosine hydroxylase activity is dependent on depolarization of postsynaptic adrenergic neurons.
MEMBRANE AFFINITIES AND SUBCELLULAR DISTRIBUTION OF THE DIFFERENT MOLECULAR FORMS OF CHOLINE ACETYLTRANSFERASE FROM RAT
Authors: Fonnum F. , Malthe‐Sørenssen D.
Published: October 2006

Choline acetyltransferase from rat brain is present in three different molecular forms with isoelectric points at pH 7·4‐7.6, 7·7‐7·9 and 8·3. The three forms were identified in a highly purified enzyme preparation, in a preparation of synaptosomes and in a cyto‐plasmic preparation from disrupted axons and perikarya (fraction S3). The three molecular forms differed in their affinities for synaptosome membranes and for a cation exchange resin (CM‐Sephadex C‐50). The positive surface charges of the different molecular forms and their affinities for membranes correlated well with their isoelectric points. The molecular form with jsoelectric point 8·3 had the largest positive surface charge and the highest membrane affinity. On isoelectric focusing of an extract from rat brain synaptosomes, the molecular form with isoelectric point 8·3 formed a complex with a negatively charged compound, presumably a protein. A method was developed to remove this compound by treatment with DEAE‐Sephadex or by precipitation with vinblastine. These procedures are similar to methods known to remove the neurotubular protein. The complex formation did not occur in fraction S3.
CYCLIC AMP AND PHOSPHODIESTERASE IN SYNAPTIC VESICLES FROM MOUSE BRAIN
Authors: Johnson G. A. , Boukma Sally J. , Lahti R. A. , Mathews J.
Published: October 2006

The isolation of synaptic vesicles from mouse brain by a modification of previously reported methodology is described. Homogeneity of the preparations was ascertained by electron microscopy. Vesicles thus isolated contained cyclic AMP (365 ± 44 pmol/mg of protein; mean ± S.E.M.) and adenosine 3′,5′‐monophosphate phosphodiesterase activity (500 pmol/mg of protein per 30 min). The number of vesicles in three of the vesicle preparations was determined by a visual count of grid fields under the electron microscope. The content of cyclic AMP in the vesicles was calculated at 5000‐7500 molecules/vesiclc. The presence of cyclic AMP in the synaptic vesicles from presynaptic nerve endings would support a role for this nucleotide in nerve transmission.
INTERVENTION OF BRAIN CORTEX PHOSPHOLIPIDS IN PYRIDOXAL PHOSPHATE‐DEPENDENT REACTIONS
Authors: Maniero G. , Toffano G. , Vecchia P. , Orlando P.
Published: October 2006

We have examined the role of brain cortex phospholipids in regulating some enzymic reactions specific to the CNS. The study was carried out at the level of the reactions concerned with GABA formation, both in vivo and in vitro, and included investigation of the specificity of the effect. It was found that the brain cortex phospholipids enhance the transformation of exogenous vitamin B6 into pyridoxal‐5‐phosphate by activating the pyridoxal 5‐phosphate‐kinase enzyme, in contrast to other phospholipids of different origins. The possible role of brain cortex phospholipids in regulating an enzyme contained in the soluble fraction is discussed. Moreover, it is suggested that the specific effect of the phospholipids from various sources is linked to their fatty acid composition and to be therefore dependent on the aliphatic chains.
CATION UPTAKE BY INTACT NUCLEI FROM RAT CEREBRAL CORTEX
Authors: Haljamäe H. , Waldman A. A.
Published: October 2006

A method is described for determining the uptake of cations by intact nuclei from rat cerebral cortex. The divalent cations of magnesium, manganese and calcium were found to be concentrated in the nuclear pellet to levels well above the initial concentration of the medium, whereas little uptake of either potassium or sodium was observed. The binding of divalent cations to the nuclei will produce a cationic environment quite different from that of the external medium. Such localized differences may play a role in the control of nuclear activities.
ALTERATIONS IN NINHYDRIN‐POSITIVE SUBSTANCES AND CYTOPLASMIC PROTEIN SYNTHESIS IN THE BRAINS OF ASCORBIC ACID‐DEFICIENT GUINEA PIGS1
Authors: Enwonwu C. O.
Published: October 2006

Newly‐weaned male guinea pigs were fed an ascorbic acid‐deficient diet ad libitum and compared with control animals pair‐fed an adequate diet for a similar duration. The ascorbic acid‐deficient animals demonstrated prominent elevations in serum concentrations of tyrosine (+427%), phenylalanine (+36%) and arginine (+21 %) with concomitant depressions in levels of glycine (–57 %), histidine (–39 %), ethanolamine (–38%) and glutamic acid (–22 %). With few exceptions, the alterations in the liver amino acid profiles were in the same directions as those observed in the serum. The scorbutic brains showed 28–36 per cent of the retention of total ascorbic acid found in control animals and were characterized by marked elevation (+83%) in tyrosine content, hardly any alteration in phenylalanine (–9%), and depressed levels of histidine (–33 %), arginine (–25%), phosphoserine (–50%) and GABA (–12%). The implications of such abnormal changes in free amino acid patterns were evaluated in the light of the role of some of these amino acids as precursors for the synthesis of neuroregulatory substances. No difference was observed in the brain polysomal profiles as isolated from the two groups of animals. Incubation of polysomes from ascorbic acid‐deficient brains with autologous pH 5 enzyme derived from cell sap not passed through Sephadex G‐25 revealed low uptake of [14C]phenylalanine in comparison to that for a similar system from control animals. Use of pH 5 enzymes prepared from Sephadex‐treated and dialysed cell saps eliminated the difference in specific activities of the two groups of ribosomes, an observation suggesting that ascorbic acid deficiency either intensified the activity of the inhibitory components or reduced the low molecular weight stimulatory substances present under normal conditions in the brain postmicrosomal fraction.
ENZYMATIC REGULATION OF ADENOSINE 3′,5′‐MONOPHOSPHATE (CYCLIC AMP) IN THE FREEZING EPILEPTOGENIC LESION OF RAT BRAIN AND IN HOMOLOGOUS CONTRALATERAL CORTEX
Authors: Walker J. E. , Lewin E. , Sheppard J. R. , Cromwell R.
Published: October 2006

Freezing epileptogenic lesions were made unilaterally in rat cerebral cortex. Such lesions were associated with an increase in adenyl cyclase activity and a decrease in the membrane‐associated phosphodiesterase activity, with a concomitant increase in the level of cyclic AMP. Similar, though less striking, changes occurred in homologous contralateral cortex (‘mirror focus’). The effects of cyclic AMP on brain membrane systems are discussed, with the suggestion that this substance may play an important role in the genesis of focal seizures.
PATTERN OF RNA SYNTHESIS IN THE SCIATIC NERVE OF THE HEN DURING WALLERIAN DEGENERATION
Authors: Muirhead P. D. , Mezei Catherine
Published: October 2006

The pattern of synthesis of rapidly‐labelled RNA of hen sciatic nerve was studied during Wallerian degeneration. At 2,4,8, 16 and 30 days of degeneration the proximal and distal stumps of the severed nerve as well as the intact contralateral sciatic nerve (functional control) were excised and incubated with either [5‐3H]uridine or [2‐14C]uridine for 0.5 h. The electrophoretic pattern of RNA from the normal adult sciatic nerve showed that most of the radioactivity was incorporated into RNA species migrating between the 18 S and 4 S components of the bulk RNA. The synthesis of RNA was sensitive to actinomycin‐D, an indication that it was directed by a DNA template. The electrophoretic patterns of the rapidly‐labelled RNA in the proximal and distal nerve stumps demonstrated a change following nerve section. After 2–4 days of Wallerian degeneration the degenerating distal nerves incorporated more radioactivity in the 4 S region than the corresponding controls, but at 8 and 16‐days after degeneration relatively more label appeared in higher molecular weight RNA species. In the intact sciatic nerve of the operated hens progressively more radioactivity was detected in the 4 S region with increasing time after the contralateral nerve section. At each stage of Wallerian degeneration the specific radioactivities of RNA in the control nerves from experimental hens were higher than those of the normal adult sciatic nerve. These results indicated a change of RNA metabolism in increased functional activity and during Wallerian degeneration.
THE EFFECT OF LIMB ISCHAEMIA ON THE TURNOVER OF NORADRENALINE IN THE HYPOTHALAMUS AND BRAIN STEM OF THE RAT
Authors: Stoner H. B. , Elson Patricia M. , Koltay Edit
Published: October 2006

The effect of ischaemic limb injury on the turnover of noradrenaline in the hypothalamus and brain stem has been studied in rats. There are theoretical reasons for thinking that these regions are activated in trauma and previous work showed that during limb‐ischaemia the concentration of noradrenaline in the hypothalamus decreased by 27 per cent. The tourniquets were applied to both hind‐limbs 1 h after the injection of [14C]‐tyrosine when the labelling of the noradrenaline was maximal.

During 4 h limb ischaemia the endogenous tyrosine concentration in the plasma decreased while that in the hypothalamus first rose and then fell. Changes in a similar direction in the brain stem were not statistically significant. Limb ischaemia did not affect the decline in the specific activity of the plasma or tissue tyrosine. It was concluded that the injury increased the utilization of tyrosine by the body.

During the 4 h bilateral hind‐limb ischaemia the rate of decline of [14C]noradrenaline was significantly increased in the brain stem but not in the hypothalamus. Conditions in the brain stem were sufficiently close to ‘steady‐state’ to be able to conclude that the injury increased the metabolism of noradrenaline in the brain stem. Conditions in the hypothalamus were too complicated for definite conclusions to be drawn. The possible reasons for this and the limitations of this method for studying noradrenaline turnover are discussed.
Inorganic ion effects on the kinetic parameters of acetylcholinesterase
Authors: Dawson R. M. , Crone H. D.
Published: October 2006

EARLY work on the effects of inorganic ions on the activity of acetylcholine acetyl‐hydrolase (EC 3.1.1.7; AChE) from various sources has been summarized by COHEN and OOSTERBAAN (1963) and many other reports have been published subsequently (CHANGEUX, 1966; CRONE, 1973; HELLER and HANAHAN, 1972; IVANOVA, 1967; KITZ, BRASWELL and GINSBURG, 1970; ROUF‐CALIS and QUIST, 1972; ROUFOGALIS and THOMAS, 1968; WINS, SCHOFFENIELS and FOIDART, 1970). Despite this work, no comprehensive study has yet been made to determine whether the observed effects are specific to particular ions or dependent only on the ionic strength of the medium (CHANGEUX, 1966). In some cases, specific ion effects have been observed (CHANGEUX, 1966; HELLER and HANAHAN, 1972; ROUFOGALIS and QUIST, 1972; ROUFOGALIS and THOMAS, 1968) at salt concentrations from 600 mM to below 1 mM, but the studies were not detailed enough and in some cases the total ionic strength was not rigidly controlled, so that no general deductions can be drawn.

We have studied the hydrolysis of acetylcholine (ACh) by bovine erythrocyte AChE at subinhibitory substrate concentrations, and now present our results on the effect of inorganic salts at varying ionic strength on the kinetic parameters Km, and Vmax. The present work shows that this hydrolysis follows simple Michaelis kinetics very closely, and therefore these two constants suffice to define the complete pattern of initial reaction velocity as a function of substrate concentration (ATKINSON, 1966).
THE QUANTITATIVE HISTOCHEMISTRY OF ACID PROTEINASE IN THE NERVOUS SYSTEM: LOCALIZATION IN NEURONS1
Authors: Hirsch Hilde E. , Parks Mary Ellen
Published: October 2006

A new, fluorometric method was used to assay acid proteinase in tissue samples at great sensitivity. Digestion of hemoglobin at pH 3.8 (in brain mostly due to cathepsin D) was measured in individual nerve cell bodies and neuropil from the anterior horn of the spinal cord, and in the molecular and granular layers and while matter of cerebellum, in man and in monkey. Anterior horn cell perikarya were about 25 times more active than neuropil, and the granular layer of cerebellum had about three times the activity of the molecular layer. This predominantly neuronal localization resembles the distribution of other lysosomal hydrolases. The high capacity for protein breakdown found in neurons is in accord with their known high rates of protein synthesis and turnover.
SUBCELLULAR LOCALIZATION OF NEWLY‐FORMED [3H]ACETYLCHOLINE IN RAT CEREBRAL CORTEX IN VITRO
Authors: Molenaar P. C. , Polak R. L. , Nickolson V. J.
Published: October 2006

—Slices from rat brain cortex were incubated for either 5 or 60 min in a medium containing [3H]choline and 4·7 or 25 mm‐KCl. Bioassayable ACh and labelled ACh were determined in the incubation medium, in the total tissue homogenate and in subcellular fractions. Raising the KCl concentration from 4·7 to 25 mm stimulated the release and synthesis of total and of labelled ACh. In medium containing 25 mm‐KCl the amounts of ACh decreased in the tissue and in the nerve ending cytoplasm, but remained constant in the synaptic vesicles. After incubation in 25 mm‐KCl medium the ACh in the vesicles was labelled to the same extent as the cytoplasmic ACh but after incubation in 4·7 mm‐KCl medium vesicular ACh was labelled less than cytoplasmic ACh. During 5 min incubation in medium containing 25 mm‐KCl the ratio of labelled to total ACh was much higher in the medium than in the homogenate, the vesicles or the cytoplasm. During the last 15 min of the 60 min incubation the ratio of labelled to total ACh in the medium was still higher than that in the tissue fractions, but less so than during the 5 min incubation. It is concluded that the vesicular and cytoplasmic fractions are not identical with the store in the tissue from which newly‐synthesized ACh is preferentially released.
SIMULTANEOUS INCORPORATION OF ORALLY ADMINISTERED [9, 10‐3H2]OLEIC AND [1‐14C]LINOLEIC ACIDS INTO LIPIDS OF THE ADULT RAT BRAIN
Authors: Illingworth D. R. , Glover J.
Published: October 2006

—The incorporation of an orally administered mixture of [9,10‐3H2joleic acid and [1‐14C]linoleic acid into the brain and spinal cord lipids was maximal after 24 h compared with 4 h for extraneural tissue. In the latter, both acids were utilized equally well for triglyceride biosynthesis, but linoleate entered phosphatidylcholine more rapidly than oleate. Oleic acid was preferentially incorporated into newly synthesized cholesterol esters although 4 h after dosing most cholesterol esters present in serum were formed preferentially from linoleate presumably by the action of lecithin‐cholesterol acyl transferase.

In neural tissue, a considerable amount of [1‐14C]linoleate was metabolized to higher polyunsaturated fatty acids, whereas in the case of oleate, 90 per cent of the tritium activity remained in monoenic acids at all time periods studied. Both acids were initially incorporated most rapidly into the lecithin fraction of brain and spinal cord, but after 7 days diacyl phosphatidylethanolamine had the highest specific activity.

These data are consistent with the view that the uptake of labelled fatty acids by the brain takes place principally as free acids but that some uptake of esterified forms, probably largely as phosphatidylcholine, also occurs. The low linoleate content of the brain and probably also of cerebrospinal fluid cannot be explained on the basis of a selective restriction on the uptake of this lipid from plasma.
THE EFFECT OF AGEING ON RNA/DNA RATIOS IN BRAIN REGIONS OF THE C57BL/6J MALE MOUSE
Authors: Chaconas G. , Finch C. E.
Published: October 2006

—The effect of ageing on RNA/DNA was investigated in brain regions and liver of a healthy subpopulation of C57BL/6J male mice. A decrease of 10% in RNA/DNA was found in senescent striatum in contrast to absence of significant change in the hypothalamus, cerebellum, hippocampus, septum and liver.
ISOLATION OF AN ACID‐SOLUBLE BASIC PROTEIN FROM MONKEY BRAIN
Authors: Wedege Elisabeth
Published: October 2006

—A basic protein, soluble in 0·1 m‐perchloric acid, has been purified from brain of Macaca irus. The protein is homogeneous as indicated by ultracentrifugation, gel filtration, gel isoelectric focusing and gel electrophoresis at pH 2·9, 4·3 and 7·5. The molecular weight is estimated to be 16,000 by electrophoresis in sodium dodecyl sulphate–polyacrylamide gels. This result is in agreement with the value of 16,728 obtained from the amino acid analysis. The protein dimerizes under alkaline conditions. The predominant amino acid is glycine (15%) and the protein also contains 4% cysteine. The ratio of acidic to basic amino acids is 1·6, but a high amide content gives the protein a basic character. An isoelectric point of 9·5 is observed in gel isoelectric focusing.
ZUR ENERGIEBEDÜRFTIGEN Ca2+‐AKKUMULATION IN MITOCHONDRIEN AUS RATTENHIRN
Authors: Böhme G. , Lutze G. , Pollak K.‐H. , Winter O. , Thews J. , Kassebaum I.
Published: October 2006

—(1) The properties of a preparation of functional intact rat brain mitochondria are described and the resulting fraction is enzymatically characterized.

(2) These mitochondria are able to accumulate Ca2+ in a respiration‐dependent reaction without additions of Pi and/or adenine nucleotides.

(3) As criteria the increased acidity of the incubation medium accompanying the energy‐dependent Ca2+ accumulation, its inhibition by rotenon and Antimycin A, the acceleration of respiration and the redox change of the pyridine nucleotides were recorded and Ca2+ accumulation by the mitochondria was determined by complexemetric methods.

(4) The maximum Ca2+ accumulation by rat brain mitochondria amounts to only 25 per cent of that by rat liver mitochondria under similar conditions (on the base per mg protein); after addition of 1 mm‐ADP (without Pi) the comparable value was about 50 per cent.
TYROSINE HYDROXYLASE OF SHEEP BRAIN: SOME CATALYTIC AND CHEMICAL PROPERTIES OF THE DETERGENT‐SOLUBILIZED, PARTIALLY PURIFIED ENZYME1
Authors: Poillon W. N.
Published: October 2006

Abstract– Detergent‐solubilized tyrosine hydroxylase from the caudate nucleus of the sheep was purified 3‐fold by affinity chromatography on 3‐iodotyrosine modified agarose. Supplementation of the standard assay with 1 mM Fe2+ resulted in only slight stimulation of the enzymic activity. The enzyme was, however, markedly inhibited by certain complexing agents specific for either Fe2+ or Fe3+. Double reciprocal plots of the kinetic data for a representative complexing agent, bathophenanthroline, showed the inhibition to be competitive with O2 (apparent Km 0.15 mM) and noncompetitive with either l‐tyrosine or the synthetic tetrahydropterin cofactor DMPH4 (apparent Km's 0.12 and 0.29 mM, respectively). The combined inhibition and kinetics studies strongly suggest that brain tyrosine hydroxylase is an iron enzyme. Furthermore, the prosthetic iron very likely participates directly in catalytic function, presumably by binding molecular oxygen.

The activity of ammonium sulphate‐precipitated enzyme was found to be stimulated 2‐fold by Fe2+, catalase or peroxidase, while untreated enzyme was markedly less affected by these agents. Since the only ostensible difference between the two preparations was the extensive aggregation present in the former case, the change in physical state evoked by ammonium sulphate precipitation appeared to be somehow related to this peculiar property of the enzyme.
PARTIAL PURIFICATION AND CHARACTERIZATION OF NADPH‐LINKED ALDEHYDE REDUCTASE FROM MONKEY BRAIN1
Authors: Bronaugh R. L. , Erwin V. Gene
Published: October 2006

Abstract— The activity of NADPH‐linked aldehyde reductase (EC 1.1.1.2) in various regions of monkey brain was determined in vitro. The highest specific activity of the enzyme was found in areas of the brain stem; including the pons, medulla and midbrain. A greater than 500‐fold purification of the monkey brain enzyme was obtained by a combination of ammonium sulphate fractionation and subsequent chromatography on calcium phosphate gel cellulose and DEAE‐cellulose. The aldehyde metabolites of the biogenic amines, norepinephrine, serotonin, dopamine and octopamine, were readily reduced by the NADPH‐linked aldehyde reductase. The Km values for 3,4‐dihydroxyphenylglycolaldehyde, 3,4‐dihydroxyphenyl‐acetaldehyde, and 5‐hydroxyindoleacetaldehyde were 12.0 μm, 6.1 μm and 27 μm, respectively. The maximum velocity (Vmax) for 3,4‐dihydroxyphenylglycolaldehyde was, respectively, five‐fold or three‐fold greater than that determined for 3,4‐dihydroxyphenylacetaldehyde or 5‐hydroxyindoleacetaldehyde. The highly purified enzyme derived from monkey brain was markedly inhibited by barbiturates, diphenylhydantoin, and chlorpromazine, but not by pyrazole. From data obtained by sucrose density gradient centrifugation and Sephadex chromatography the molecular weight of aldehyde reductase was determined to be about 70,000 daltons.
SUSTAINED DRUG‐INDUCED ELEVATION OF BRAIN GABA IN THE RAT1
Authors: Perry T. L. , Hansen Shirley
Published: October 2006

Abstract— The contents of GABA, homocarnosine, and β‐alanine can be raised in rat brain for long periods of time by the continued administration of phenelzine, aminooxyacetic acid (AOAA), or isonicotinic acid hydrazide (INH). These 3 compounds apparently act by preferential inhibition of the enzyme GABA aminotransferase (GABA‐T). Oral administration of phenelzine (20 mg/kg per day) caused a 25–50 per cent increase in GABA levels in rat brain, but produced appreciable toxic side effects. A similar increase in GABA levels in brain resulted from oral administration to rats of INH in a dosage of 60 mg/kg per day, without production of any obvious toxic effects. Simultaneous administration of large doses of pyridoxine did not abolish the GABA‐elevating effect of INH. Brain GABA levels in the rat were increased by approx. 50 per cent by daily injections of AOAA (2.5 mg/kg per day). At this low dosage, AOAA injections in rats could be continued for at least 6 weeks without producing evident toxic effects. Oral administration of large amounts of GABA, on the other hand, failed to increase the content of GABA in the brains of rats not treated with GABA‐T inhibitors, and failed to produce any further increase of brain GABA levels in rats treated with AOAA.
ACTIVITY OF CYCLIC AMP‐DEPENDENT MICROSOMAL PROTEIN KINASE AND PHOSPHORYLATION OF RIBOSOMAL PROTEIN IN RAT BRAIN DURING POSTNATAL DEVELOPMENT
Authors: Schmidt M. J. , Sokoloff L.
Published: October 2006

Abstract— Microsomes from rat brain exhibited protein kinase activity which was stimulated by cyclic AMP when assayed in the presence of exogenous protein substrate, such as thymus histone. In the absence of exogenous substrate some phosphorylation of microsomal protein occurred, but no stimulation by cyclic AMP could be discerned, probably because of limitations of substrate. The maximal activity of microsomal protein kinase observed in the presence of saturating concentrations of histone and the optimal concentration (5 μm) of cyclic AMP remained essentially unchanged from birth to early adulthood, but the magnitude of the stimulation by cyclic AMP was significantly higher at birth than at 30 days of age. Brain ribosomal proteins could be phosphorylated by the cyclic AMP‐dependent brain protein kinase. Their total capacity for acceptance of phosphate by means of this phosphorylation reaction remained unchanged throughout the postnatal development of the brain. Our results are consistent with the possibility that phosphorylation of ribosomal protein mediated by cyclic AMP‐dependent protein kinase may play a a role in the postnatal regulation of cerebral protein synthesis, as a result of the changes in the levels of cyclic AMP known to occur in brain during postnatal maturation.
BIOSYNTHESIS AND COMPOSITION OF BRAIN GALACTOLIPIDS IN NORMAL AND HYPOTHYROID RATS
Authors: Mantzos J. D. , Chiotaki L. , Levis G. M.
Published: October 2006

Abstract— Newborn rats were rendered hypothyroid by methimazole treatment. Incorporation of [1‐14C]galactose both in vivo and in vitro into brain cerebrosides of hypothyroid rats was significantly lower than in normals. Biosynthesis of sulphatides was affected by hypothyroidism to a smaller extent than cerebrosides. Assay of cerebroside biosynthesis from [1‐14C]galactose or UDP‐[1‐14C]galactose by brain preparations revealed that incorporation of the sugar in both cases is affected to the same extent by methimazole treatment, suggesting that the phenomenon is not due to impairment of the nucleotide biosynthesis. A radioactive galactolipid tentatively characterized as glycerogalactolipid was synthesized in vitro and its biosynthesis was reduced to a large extent in the brain preparations from hypothyroid rats. The fatty acid composition of cerebrosides and sulphatides from the brains of hypothyroid rats was found to be different from that of normal rats. The percentage of normal C24 fatty acids was significantly decreased in the methimazole‐treated rats. Brain sphingomyelin fatty acids did not differ between normal and hypothyroid rats.
SOME ASPECTS OF PYRIDOXAL PHOSPHOKINASE IN CHICK BRAIN1
Authors: Twomey S. L. , Baxter C. F.
Published: October 2006

Abstract— The activity of pyridoxal phosphokinase (EC 2.7.1.35) has been studied in two brain areas of the White Leghorn chick during post‐hatch development. Activities of this enzyme were approximately the same in both forebrain and cerebellum at 2 days of age but when maximum activity was reached, at 20‐25 days, the enzyme activity in forebrain was considerably higher than in the cerebellum. In homogenates, the activity of pyridoxal phosphokinase (as measured by pyridoxal phosphate formation) was inhibited by a particulate‐bound inhibitor. In the forebrain of the 15‐day‐old chick, this inhibitor was detected in concentrations 3‐ to 5‐fold greater than in the cerebellum. The inhibitor appeared to be an atypical ATPase which approached adult levels in the chick forebrain by two days after hatching. The possible physiological significance as well as the possible artifactual nature of this pyridoxal phosphokinase inhibitor in the in vitro assay system has been considered.
ACCUMULATION OF CYCLIC ADENOSINE 3′, 5′‐MONOPHOSPHATE IN CEREBRAL CORTICAL SLICES FROM RAT AND MOUSE: STIMULATORY EFFECT OF α‐ AND β‐ADRENERGIC AGENTS AND ADENOSINE
Authors: Schultz J. , Daly J. W.
Published: October 2006

Abstract— Norepinephrine, epinephrine, isoproterenol, and adenosine elicit enhanced accumulations of cyclic AMP in incubated slices of rat cerebral cortex. Combinations of norepinephrine, epinephrine, isoproterenol, or histamine with adenosine have a greater than additive effect on cyclic AMP levels. The effects of isoproterenol appear to be mediated via a classical β‐adrenergic receptor whereas the effects of norepinephrine appear due to interactions with both α‐ and β‐adrenergic receptors. The presence of the phosphodiesterase inhibitor, isobutylmethylxanthine, potentiates the effects of the catecholamines and reveals a histamine‐mediated increase in cyclic AMP levels. After an initial stimulation of cyclic AMP formation with norepinephrine, followed by washing of the slices, the cyclic AMP‐generating system is unresponsive to norepinephrine but does respond to an adenosine‐norepinephrine combination. In mouse cerebral cortical slices, catecholamines appear to elicit an accumulation of cyclic AMP primarily via interaction with a β‐adrenergic receptor.
EFFECTS OF ATP ON THE ACTIVITY OF NUCLEOSIDE 3′,5′‐CYCLIC MONOPHOSPHATE PHOSPHODIESTERASE FROM BRAIN
Authors: Teshima Y. , Yamazaki R. , Kakiuchi S.
Published: October 2006

ATP is known to inhibit the phosphodiesterase activity in the supernatant fraction of the brain homogenate. Results showed that, when enzyme activity was assayed by determining the change in the concentration of substrate, the magnitude of the inhibition by 2 ∼ 3 mm‐ATP was not more than 20% and this effect of ATP can be explained mainly, if not entirely, on the basis of chelation of ATP with Mg2+ and Ca2+in vitro, both of which are necessary for enzyme activity. When brain phosphodiesterase was assayed by measuring 5′‐AMP (product), the effect of ATP was erroneously exaggerated. This is due to ATP‐dependent conversion of 5′‐AMP to inosinic acid catalysed by adenylate deaminase in the crude preparation.
EFFECT OF INCREASED RAT BRAIN TRYPTOPHAN ON 5‐HYDROXYTRYPTAMINE AND 5‐HYDROXYINDOLYL ACETIC ACID IN THE HYPOTHALAMUS AND OTHER BRAIN REGIONS
Authors: Knott P. J. , Curzon G.
Published: October 2006

—Tryptophan was found at higher concentration in the rat hypothalamus than in other brain regions. This difference was explicable neither by regional differences in blood content nor by differences in tryptophan recovery from different weights of tissue. It was not due to interference by other known brain indoles. After food deprivation or tryptophan injection the tryptophan concentration rose in all regions. Total 5‐hydroxyindole increases showed regional differences but relative changes were similar after both procedures. Increases in 5‐hydroxytryptamine were clearest in midbrain + hippocampus. In general, 5‐hydroxyindolylacetic acid increased more markedly than 5‐hydroxytryptamine. The hypothalamus appeared refractory with negligible increases of both 5‐hydroxyindoles upon either food deprivation or tryptophan administration even though hypothalamic tryptophan concentration rose considerably. Results are discussed in relation to other evidence suggesting special characteristics of 5‐HT regulation in the hypothalamus.
THE CATION SENSITIVITY OF THE ACETYLCHOLINE RECEPTOR FROM TORPEDO CALIFORNICA
Authors: Schmidt J. , Raftery M. A.
Published: October 2006

—The effects of various cations and cholinergic ligands on the rate of α‐bungarotoxin‐acetylcholine receptor complex formation has been studied by means of a DEAE‐cellulose disk assay technique. The reaction rate is reduced to one half the initial rate in the presence of 2·5 · 10−6m acetyleholine. a value close to the observed KD of ACh measured by equilibrium dialysis. Inhibition constants of about 5 mM were obtained for most monovalent cations whereas divalent cations gave inhibition constants of 0·05‐0·2 mm. The rate and extent of toxin‐receptor complex formation was also investigated as a function of hydrogen ion concentration; the rate of formation reaches a maximum at pH 7·5 and a group with a pK about 6 inhibits toxin binding to the receptor when protonated.

These data can be correlated with the observed effects of inorganic cations on the binding of cholinergic ligands in vivo at the neuromuscular junction. Given the affinities of the individual cations, it is possible to predict how the apparent affinity of a cation‐sensitive cholinergic ligand will change with variations of buffer composition.
ANABOLIC RESPONSES OF EMBRYONIC DORSAL ROOT GANGLIA TO NERVE GROWTH FACTOR, INSULIN, CONCANAVALIN A OR SERUM IN VITRO
Authors: Burnham Patricia A. , Silva J. A. , Varon S.
Published: October 2006

—Intact and dissociated dorsal root ganglia from 8‐day chick embryos were examined for their ability to incorporate radio‐precursors into RNA and protein in unsupplemented medium or in medium supplemented with Nerve Growth Factor, insulin, Concanavalin A, fetal calf serum, or several combinations of such agents. In the absence of any agent, incorporation into RNA and protein declined with time. All four agents maintained or improved the initial incorporation rates, and optimal doses were determined in each case. Different combinations of two agents led to potentiated, full or partially additive, or inhibited effects; in particular, NGF promoted incorporation even in conjunction with insulin (additive) or serum (potentiating). Several differences were noted between the responses of intact and of dissociated ganglia.
PHOSPHOLIPID METABOLISM IN EXPERIMENTAL ALLERGIC ENCEPHALOMYELITIS: ACTIVITY OF BRAIN PHOSPHOLIPASE A1, TOWARDS SPECIFICALLY LABELLED GLYCEROPHOSPHOLIPIDS
Authors: Woelk H. , Kanig K.
Published: October 2006

—The activity of phospholipase A1 (phosphatide acylhydrolase, EC 3.1.1.4) was measured against phosphatidylcholine, ‐ethanolamine and ‐serine, specifically labelled with different fatty acids at either the 1 or 2 position, during experimental allergic encephalomyelitis in rats. In the acute stage of the disease there was a significant increase in enzyme activity in comparison to that from the control animals. The enhanced phospholipase A1 activity was of the‐same order of magnitude for all 1,2‐diacyl‐glycerophospholipids investigated. The phospholipase A1‐catalysed release of labelled fatty acids from molecular species of phosphatidylcholine decreased slightly with increasing degree of unsaturation of the fatty acids at the 1‐position. The Km‐values of the highly purified enzyme were not altered by the demyelinating disorder. The phospholipase A1 activity returned to the control level in the recovery stage.
FETAL DEVELOPMENT: THE EFFECTS OF MATURATION ON IN VITRO PROTEIN SYNTHESIS BY MOUSE BRAIN TISSUE
Authors: Gilbert B. E. , Johnson T. C.
Published: October 2006

—The elucidation of the translational regulatory events which function during the critical fetal and neonatal period is an important prerequisite to our understanding of normal, as well as abnormal, brain growth and differentiation. Brain cell suspensions and cell‐free homogenates were employed to study the protein synthetic activity during the maturation of fetal‐ neural tissue. The results clearly demonstrated that while neural tissue from 1‐day postnatal mice was 10 times more active in protein synthesis than brain tissue from adult mice, the former was many fold less active in translational events than fetal neural tissue from 13‐day post‐zygotic mice. Fetal polypeptide synthetic activity was found to decrease from the 13th day to the 19th day post‐zygotic. This decrement in the translational activity was not due to amino acid availability or pools, or to differences, quantitatively or qualitatively, in polysome concentrations. The enhanced rate of protein synthetic activity measured with neural tissue from 13‐day post‐zygotic mice was shown to be due to an increase in rate of protein synthesis and not to an enhanced rate of protein degradation.
IN VITRO Ca2+ DEPENDENT PROTEOLYSIS IN BRAIN TISSUES: A POSSIBLE SOURCE OF ERROR IN TRANSMITTER METABOLISM STUDIES
Authors: Hamon M. , Bourgoin S. , Hery F. , Glowinski J.
Published: October 2006

—The effects of Ca2+ ions on the metabolism of [3H]serotonin and [3H]‐labelled catecholamines have been examined in hippocampal slices or synaptosomes. The formation of [3H]‐5 hydroxyindoles ([3H]serotonin + [3H]‐5 hydroxyindoleacetic acid) from [3H]tryptophan and that of [3H]‐labelled catecholamines from [3H]tyrosine were increased when Ca2+ was omitted from the incubating medium. However, the total synthesis of 5‐HT from tryptophan and that of catecholamines from tyrosine did not seem to be significantly changed. Altered formation of tritiated amines were due to changes in the specific activities of respective precursor amino acids. This reflected altered sizes of the free amino acid pools caused by Ca2+‐dependent in vitro proteolysis. This must be taken into consideration when studying in vitro Ca2+ dependency of neutrotransmitter metabolism.
DEPLETION OF TRYPTOPHAN HYDROXYLASE BY 5,6‐DIHYDROXYTRYPTAMINE IN RAT BRAIN—TIME COURSE AND REGIONAL DIFFERENCES1
Authors: Victor S. J. , Baumgarten H. G. , Lovenberg W.
Published: October 2006

—Wistar rats were injected intraventricularly with 75 μg 5,6‐dihydroxytryptamine. Tryptophan hydroxylase was assayed in seven regions of the brain as well as spinal cord at intervals following injection. Spinal cord was depleted to 1 per cent of control by 12 days. Tectum was depleted to 32 per cent of control by 9 days. The time course of depletion in most regions was biphasic, with an early reduction of activity 1 h after injection with continued reduction of activity 1‐2 days following injection, and a recovery of activity at 4‐6 days. The activity again drops at 9‐12 days, and this reduction of activity persists to varying degrees to 60 days, with slight recovery at this time in certain regions.