bluuebunny/crossref_metadata_2025 huggingface dataset:
CHANGES IN GLUTAMIC ACID AND GLUTAMINE METABOLISM IN THE RAT BRAIN AFTER WHOLE BODY X‐IRRADIATION
Authors: Hǎulicǎ A. , Trandafirescu M. , Ababei L.
Published: October 2006

Abstract—

After whole body irradiation with X‐rays, an increase in the free ammonia concentration in the rat brain was observed. Parallel to this increase, evidence was found of a strong activation of glutaminase. Incubation increased the endogenous ammonia‐forming capacity of brain homogenates to a much greater extent in irradiated rats than in normal rats.

Glutamine synthetase activity decreased within the first 2 h after irradiation but remained unchanged at 24 and 96 h after irradiation. On the other hand, at 48 h after irradiation, glutamate dehydrogenase activity in the brain had fallen by 75 per cent in comparison with the initial activity. It is concluded that metabolic systems other than the glutamine‐glutamic acid system contribute to the ammonia formation in the brain after irradiation.
THE EFFECT OF AUDIOGENIC SEIZURES ON REGIONAL CNS ENERGY RESERVES, GLYCOLYSIS AND CITRIC ACID CYCLE FLUX1
Authors: Ferrendelli J. A. , McDougal D. B.
Published: October 2006

Selected energy reserves, glycolytic intermediates and citric acid cycle intermediates were measured in the cerebral cortex, thalamus, brain stem, cerebellum and spinal cord of susceptible mice during audiogenic seizures. Changes in energy reserves (ATP, phosphocreatine and glucose) differed strikingly in extent and temporal pattern from region to region. The audiogenic seizure produced a transient, large decrease in thalamic energy reserves during the early, pretonic phase of the seizure. Less extensive decreases were observed in brain stem and spinal cord; but in these latter regions the changes persisted throughout the pretonic and tonic phases of the seizures. In cerebellum there was a biphasic decrease in energy reserves; a small decrease was observed immediately after the sound stimulus and a second much greater decrease was observed during the tonic phase of the seizure. No change in energy reserves was observed in cerebral cortex. Changes in glycolytic intermediates (glucose 6‐phosphate, fructose diphosphate, pyruvate and lactate) also varied from region to region in response to the decreases in energy reserves. In contrast, changes in the two citric acid cycle intermediates, α‐oxoglutarate and malate, were essentially the same in all regions studied. α‐Oxoglutarate decreased during the tonic phase of the seizure and rose during recovery. Malate remained at control levels throughout the seizure and then slowly increased.

These findings are interpreted as indicating regional variations in nueronal activity during audiogenic seizures. During the period when clinical seizure activity is apparent neuronal activity increases in the subcortical regions. This is reflected by an increase in energy utilization and an increase in glycolytic flux in these areas. However, a concomitant increase in citric acid cycle flux does not seem to occur during this period. Citric acid cycle flux does appear to increase after the seizure is over.
SYNTHESIS OF GLYCOPROTEINS AND GANGLIO‐SIDES IN DEVELOPING RAT BRAIN
Authors: Quarles R. H. , Brady R. O.
Published: October 2006

Abstract— Intracerebral injections of radioactive fucose into developing rats resulted in specific labelling of the brain glycoproteins in their fucose moieties. Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulphate revealed that the radioactive glycoproteins were very heterogeneous with regard to molecular weight. A procedure utilizing [3H]fucose and [14C]fucose together with double‐label counting techniques was developed for comparing the electrophoretic patterns of newly synthesized glycoproteins from different samples of tissue. By the use of this procedure we showed that the incorporation of radioactive fucose into the glycoproteins of high mol. wt. was relatively greater in the brains of 5‐day‐old rats than in those of 25‐day‐old rats. Intracerebral injection of N‐[Ac‐3H]acetyl‐d‐mannosamine resulted in a high degree of specificity for the labelling of sialic acid moieties in glycoproteins and gangliosides. The ratio of the d.p.m. of N‐[3H]acetylmannosamine incorporated into glycoproteins to the d.p.m. incorporated into gangliosides was higher in 5‐day‐old rats than in 15‐ or 25‐day‐old rats. Experiments in which 15‐day‐old rats were injected with a mixture of [14C]fucose and N‐[3H]acetylmannosamine showed that there were differences in the relative degrees of incorporation of the two radioactive precursors into the various glycoproteins. The greatest incorporation of [14C]fucose relative to that of N‐[3H]acetylmannosamine occurred in some of the glycoproteins of smaller mol. wt.
PYRIMIDINE BIOSYNTHESIS IN RAT BRAIN1
Authors: Bourget P. A. , Tremblay G. C.
Published: October 2006

—Studies on the incorporation of [14C]NaHCO3 into both orotic acid and RNA in tissue slices reveal the occurrence of the complete orotate pathway for the de novo biosynthesis of pyrimidines in the rat brain. A comparison of the rates of incorporation of bicarbonate into orotic acid and RNA in tissue slices of brain and liver indicate the brain to be one‐fourth to one‐half as active as the liver in the de novo biosynthesis of pyrimidines. The results of this study favor the proposal that the adult rat brain can meet its needs for pyrimidines through de novo synthesis and is not dependent upon salvage activity and an extraneural supply of pyrimidines.
PURIFICATION OF PHOSPHATE‐DEPENDENT PIG BRAIN GLUTAMINASE
Authors: Svenneby G. , Torgner I. Aa. , Kvamme E.
Published: October 2006

Abstract— A procedure for preparing highly purified phosphate‐activated glutaminase (EC 3.5.1.2, L‐glutamine amidohydrolase) from pig brain is described. The main steps consist of extraction with acetone, followed by sodium sulphate fractionation of the solubilized acetone powder. Thereafter, solubilization by dialysis against a buffer containing tris‐HC1, mercaptoethanol, and EDTA, followed by precipitation with phosphate‐borate, is repeated twice. The final preparation contains no impurities which can be detected by polyacrylamide gel electrophoresis, isoelectric focusing, and sedimentation equilibrium centrifugation. By the latter method, molecular weight is determined to be 187,000. By polyacrylamide gel electrophoresis in sodium dodecyl sulphate, one protein band with molecular weight 64,000 is found.
BIOSYNTHESIS OF SEROTONIN IN RAPHÉ NUCLEI OF RAT BRAIN: EFFECT OF p‐CHLOROPHENYLALANINE1
Authors: Deguchi T. , Sinha A. K. , Barchas J. D.
Published: October 2006

The activity of tryptophan hydroxylase (EC 1.99.1.4) in the region of the raphé nuclei of rat brain was higher than that of any other brain area. The content of serotonin and the rate of serotonin synthesis were also highest in the raphé nuclei. Following the administration of p‐chlorophenylalanine the injection of tryptophan and pargyline increased the content of serotonin in the region of the raphé nuclei of rat brain. The results suggest that the raphé nuclei retained the capacity to hydroxyl‐late tryptophan to some extent after the injection of p‐chlorophenylalanine.
RESPIRATION BY CULTIVATED ASTROCYTES AND NEURONS FROM THE CEREBRAL HEMISPHERES
Authors: Dittmann L. , Sensenbrenner M. , Hertz L. , Mandeli P.
Published: October 2006

‐Rates of oxygen uptake were measured in chick and/or rat astrocytes and neuronal cells cultivated for 2–4 weeks in Falcon flasks or Rose chambers. All the preparations were found to have respiratory rates between 0.4 and 0.8 × 10−5μl/h O2 per cell. Based upon measurements of cell diameters these values were recalculated to about 570 μmol/g wet wt. for the neuronal cells and 130 μmol/g wet wt. for the glial cells. The results are compared with previous data of oxygen uptake by neurons and glial cells separated by other procedures.
DEPOLARIZING STIMULI AND THE RELEASE OF PHYSIOLOGICALLY ACTIVE AMINO ACIDS FROM SUSPENSIONS OF MAMMALIAN SYNAPTOSOMES
Authors: Bradford H. F. , Bennett G. W. , Thomas A. J.
Published: October 2006

—Potassium causes increased metabolism and release of physiologically active amino acids from suspensions of mammalian synaptosomes. Sheep and rat hypothalamic synaptosomes, and rabbit, sheep and rat cortical synaptosomes show respiratory and glycolytic response to electrical stimulation and show a parallel calcium‐dependent differential release of physiologically active amino acids. Attempts were made to eliminate the actions of heating and electrode products as the agents causing the observed effects and the case is made that depolarization is the trigger mechanism.
EVIDENCE FOR THE CLOSE ASSOCIATION OF A GLYCOPROTEIN WITH MYELIN IN RAT BRAIN
Authors: Quarles R. H. , Everly J. L. , Brady R. O.
Published: October 2006

Abstract— Myelin was purified from rats which had been injected intracerebrally with radioactive fucose in order to label specifically the glycoproteins. Myelin contained a small amount of fucose‐labelled glycoproteins in comparison to that in other subcellular fractions, but polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulphate revealed a unique pattern of radioactive glycoproteins dominated by a major peak. The same glycoprotein was not prominent in the other subcellular fractions which were examined. This major glycoprotein in the myelin fraction was also labelled after injection with [3H]glucosamine or N‐[3H]acetylmannosamine. It was the most intensely staining myelin protein when gels were treated with periodic acid‐Schiff reagents, an indication that, in terms of protein‐bound carbohydrate, it is the major glycoprotein in the myelin fraction. The glycoprotein was present in myelin purified from rats ranging in age from 14 days to 14 months. Extensive recycling of the myelin through the purification procedures did not significantly reduce the amount of glycoprotein in the myelin. Double label experiments with [3H]fucose and [14C]fucose were used to compare glycoproteins in myelin purified from white and grey matter, respectively, and from mixed homogenates of myelinated and unmyelinated brain. The results obtained from these experiments suggested that the glycoprotein is closely associated with myelin and that it is not in an unrelated contaminating structure. Possible locations of the glycoprotein are discussed. They include the myelin membrane itself, the oligodendroglial plasma membrane, and the axolemma of myelinated axons.
BIOCHEMICAL COMPOSITION OF DIFFERENT REGIONS IN BRAINS OF SMALL‐FOR‐DATE INFANTS
Authors: Sarma M. K. Janardana , Rao Kalluri Subba
Published: October 2006

Different regions of the brains of babies born with low birth weights for the gestational age (small‐for‐date infants) were analysed for various chemical constituents. The brains of small‐for‐date babies were reduced in size. On a percentage basis, cerebellum and medulla oblongata were more affected than cerebrum. Cellularity, estimated by DNA content, was affected only in the cerebrum. However, the cell size and the concentrations of various constituents (proteins, lipids, different classes of lipids) studied in different regions of the brains of small‐for‐date infants remained unaffected compared to those found in the normal brains.
SUBCELLULAR DISTRIBUTION OF SUBSTANCE P IN BOVINE HYPOTHALAMUS AND SUBSTANTIA NIGRA
Authors: Duffy M. J. , Mulhall D. , Powell D.
Published: October 2006

Abstract— Subcellular distribution of substance P as measured by radioimmunoassay was studied in fractions and subfractions from bovine hypothalamus and substantia nigra. Most of the substance P was found in the crude mitochondrial fraction. Subfractionation of the crude mitochondrial fraction by density gradient centrifugation showed most of substance P was present in nerve ending particles. Subcellular particle integrity was assessed using enzyme markers.
EFFECTS OF CHRONIC ETHANOL INGESTION ON BRAIN AMINOACYL‐tRNA SYNTHETASES AND tRNA
Authors: Fleming E. W. , Tewari S. , Noble E. P.
Published: October 2006

Abstract—

The effects of chronic ethanol ingestion on the in vivo aminoacylation of brain transfer RNA (tRNA) were examined in C57BL/6J mice. A pronounced inhibition in the formation of [14C]leucy]‐tRNA and [14C]phenylalanyl‐tRNA was observed in the ethanol drinking mice. Properties of aminoacyl‐tRNA synthetases and tRNA were examined following their separation and isolation on a DEAE‐cellulose column. Synthesis of [14C]leucyl‐tRNA was found to have a complete dependence on ATP and Mg2+. Incubations were carried out by cross‐matching tRNA from control rat brain with synthetases obtained from the brains of control or ethanol‐drinking mice. Under these conditions, a decreased ability for aminoacylation could be demonstrated when the source of enzyme was derived from ethanol‐treated brain. The data indicate that the major effect of ethanol ingestion on the aminoacylation reaction is exerted on aminoacyl‐tRNA synthetases.
GAS CHROMATOGRAPHIC–MASS SPECTROMETRIC ANALYSIS OF BIOGENIC AMINES IN IDENTIFIED NEURONS AND TISSUES OF HIRUDO MEDICINALIS
Authors: McAdoo D. J. , Coggeshall R. E.
Published: October 2006

—Previous workers have reported that the colossal cells of Retzius in the segmental ganglia of the medicinal leech contain about 2.3 pmol of 5‐hydroxytryptamme (5‐HT)/cell body. We verify the identify of 5‐HT in the Retzius cells by gas chromatography‐mass spectrometry and derive concentrations of 1.3–4.1 pmol/neuron by analyses of eight individually dissected Retzius cell bodies. The Retzius cell bodies contain about 30% of the 5‐HT in each ganglion. An average of 25 pmol 5‐HT/mg tissue, a concentration about 500 times lower than that in the Retzius cell, was found in the fibrous, pigmented tissue surrounding the leech nervous system. We could not detect γ‐aminobutyric acid, octopamine, dopamine or norepinephrine in the Retzius cells, in the pigmented tissue, or, with the possible exception of dopamine (±0.4 pmol/ganglion), in whole ganglia. Furthermore, we could not detect 5‐HT in pooled samples of 100 non‐chromaffin control neurons.
EFFECTS OF LIGHT ON CYCLIC GMP METABOLISM IN RETINAL PHOTORECEPTORS
Authors: Krishna G. , Krishnan N. , Fletcher R. T. , Chader G.
Published: October 2006

Abstract— Guanylate cyclase activity of dark‐adapted bovine rod outer segments demonstrates a biphasic pattern upon exposure to light. By 10 s of illumination, activity is 20% lower than that observed in dark‐adapted outer segments. Activity subsequently increases and then slowly declines to two‐thirds of the original activity after 10 min of illumination. In the presence of GTP or ATP, hydrolysis of cyclic GMP is rapidly enhanced by exposure of outer segments to light; the magnitude of this effect is dependent on the amount of substrate present. The rapid effects of light on synthesis and degradation of cyclic GMP indicate that these reactions may be involved in the visual process. The concentration of guanosine 3′:5′‐cyclic monophosphate (cyclic GMP) is extraordinarily high in dark‐adapted bovine rod outer segments and is at least 100‐fold that of adenosine 3′:5′‐cyclic monophosphate (cyclic AMP). No significant decrease in the level of cyclic GMP or cyclic AMP was observed however upon exposure of dark‐adapted outer segments to light.
PROTEINS AND GLYCOPROTEINS IN MYELIN PURIFIED FROM THE DEVELOPING BOVINE AND HUMAN CENTRAL NERVOUS SYSTEMS
Authors: Everly J. L. , Quarles R. H. , Brady R. O.
Published: October 2006

Abstract—

Myclin was purified from bovine and human midbrain at various stages of prenatal and postnatal development. Basic protein and proteolipid proteins were the major individual proteins at all stages. The specific activity of 2′3′‐cyclic nucleotide 3′‐phosphohydrolase remained constant in the bovine myclin during development but decreased slightly in human myelin. A high molecular weight glycoprotein with electrophoretic mobility similar to that previously reported in rodent myelin (QUARLES et al., 1973) was present in both bovine and human myelin at all stages of development. The intensity of staining of this glycoprotein with periodic acid‐Schiff reagents per mg total myelin protein was less in mature bovine and human myelin than in rat myelin.
THE SYNTHESIS OF ACETYLCHOLINE FROM ACETYL‐CoA, ACETYL‐DEPHOSPHO‐CoA AND ACETYLPANTETHEINE PHOSPHATE BY CHOLINE ACETYLTRANSFERASE
Authors: Banns Heather , Hebb Catherine , Mann S. P.
Published: October 2006

Abstract— The synthesis of ACh by choline acetyltransferase (ChAc) has been examined using acetyl‐CoA, acetyl‐dephospho‐CoA and acetylpantetheine phosphate. At pH 7.5 Km values of 25.7 μm for acetyl‐CoA, 54.8 μm for acetyl‐dephospho‐CoA and 382 μm for acetylpantetheine phosphate were obtained and are similar to those at pH 6.0. This indicates that the 3‐phosphate may not be required for binding the substrate to the enzyme unlike carnitine acetyltransferase.

Inhibitor constants (Ki) for CoA, dephospho‐CoA and pantetheine phosphate were also measured and when considered with the Km values obtained for the acetyl derivatives it is concluded that acetyl‐dephospho‐CoA could be a successful acetyl donor in the synthesis of ACh.

Acetyl‐dephospho‐CoA was found to be less satisfactory as a substrate for citrate synthase.
ACTIONS OF l‐ AND d‐HOMOCYSTEATE IN RAT CNS: A CORRELATION BETWEEN LOW‐AFFINITY UPTAKE AND THE TIME COURSES OF EXCITATION BY MICROELECTROPHORETICALLY APPLIED L‐GLUTAMATE ANALOGUES
Authors: Cox D. W. G. , Headley M. H. , Watkins J. C.
Published: October 2006

Abstract— A correlation has been attempted between the uptake characteristics of l‐ and d‐homocysteate and the time courses of neuronal excitation by these and other amino acids related to l‐glutamate.

The uptake of l‐ and d‐homocysteate and of l‐[35S]homocysteate was studied in individual slices of rat cerebral cortex at 37°C. Tissue: medium ratios attained over l0 min for the unlabelled enantiomers at 2.5 mM were 3.7 for l‐homocysteate but only 0.8 for the d‐isomer. The uptake of l‐[35S]homocysteate over the concentration range 0.09 μm‐2 mm can be attributed mainly to a low‐affinity transport process with Km approx 3 mm and Vmax 1.7 μmol/g/min, but a high‐affinity process of low Vmax may make a minor contribution at the lower concentrations within this range. In terms of dependence on energy metabolism and [Na+], and on inhibition by p‐chloromercuriphenylsulphonate, ouabain and structural analogues of the amino acid, the main uptake system for L‐[35S]homocysteate appears to be similar to that mediating low‐affinity uptake of l‐glutamate and other acidic amino acids. d‐Homocysteate was but a weak inhibitor of this uptake system compared with other structural analogues.

The time courses of excitation by 6 amino acids were determined by microelectrophoretic application to rat spinal neurones. d‐Homocysteate induced responses with recovery times considerably longer than those of the other amino acids; this correlates with the absence of rapid uptake systems demonstrated for this amino acid in cortical tissue. d‐Glutamate and l‐homocysteate, which are only accumulated by low‐affinity transport mechanisms, induced responses with recovery periods similar to those of l‐glutamate, l‐aspartate and d‐aspartate, which are accumulated by both high‐ and low‐affinity uptake systems. Although contributions of other factors to the observed time courses, such as rates of association and dissociation of the amino acid‐receptor complexes, cannot be excluded, the present results are consistent with the hypothesis that low‐affinity uptake systems of high Vmax play an important role in the rapid termination of the effects of amino acid excitants.
RAPID AXOPLASMIC TRANSPORT IN DYSTROPHIC MICE
Authors: McLane Jerry A. , McClure William O.
Published: October 2006

Abstract— Rapid axoplasmic transport was studied in dystrophic mice of the 129/ReJ‐dy strain. Proteins transported in vivo through α‐motoneurons of the sciatic nerve were labeled by injections of [3H] or [35S] amino acids into the ventral horn of the lumbar spinal cord. Following an 18 h incubation, axoplasmic transport was quantitated by summing the radioactivity in the 10 mm length of sciatic nerve proximal to a ligation. Although the amount of transported radioactivity was small, transport appeared depressed when adult dystrophic mice were compared to controls. Transport was also studied in the sensory fibers of the sciatic nerve under in vitro conditions, resulting in high levels of transported radioactivity. In this system transport was strongly depressed. The severity of the deficiency varied with age, being small in animals with early clinical signs and becoming maximal (80–90%) in animals over 60 days of age. Proteins transported by adult dy/dy and +/+ animals were compared by gel electrophoresis using double‐label techniques. Transport of nearly all proteins was depressed in dy/dy mice, although the possibility exists that small differences occur. The data suggest that the dystrophic state produces a significant deficiency in rapid axoplasmic transport in both motor and sensory fibers, and may interfere with transport processes in all neurons. Since rapid axoplasmic transport has been associated with membranes, the data are consistent with a general alteration of cellular membranes in dystrophic animals.
[3H]GLYCOGEN HYDROLYSIS IN BRAIN SLICES: RESPONSES TO NEUROTRANSMITTERS AND MODULATION OF NORADRENALINE RECEPTORS
Authors: Quach T. T. , Rose C. , Schwartz J. C.
Published: October 2006

Abstract— Different agents have been investigated for their effects on [C3H]glycogen synthesized in mouse cortical slices. Of these noradrenaline, serotonin and histamine induced clear concentration‐dependent glycogenolysis.

[C3H]Glycogen hydrolysis induced by noradrenaline appears to be mediated by beta‐adrenergic receptors because it is completely prevented by timolol, while phentolamine is ineffective. It seems to involve cyclic AMP because it is potentiated in the presence of isobutylmethylxanthine; in addition dibutyryl cyclic AMP (but not dibutyryl cyclic GMP) promotes glycogenolysis.

Lower concentrations of noradrenaline were necessary for [C3H]glycogen hydrolysis (EC50= 0.5μM) than for stimulation of cyclic AMP accumulation (EC50= 8μM).

After subchronic reserpine treatment the concentration‐response curve to noradrenaline was significantly shifted to the left (EC50= 0.09 ± 0.02 μM as compared with 0.49 ± 0.08 μM in saline‐pretreated mice) without modifications of either the basal [C3H]glycogen level, maximal glycogenolytic effect, or the dibutyryl cAMP‐induced glycogenolytic response.

In addition to noradrenaline, clear concentration‐dependent [3H]glycogen hydrolysis was observed in the presence of histamine or serotonin. In contrast to the partial [3H]glycogen hydrolysis elicited by these biogenic amines, depolarization of the slices by 50 mM K+ provoked a nearly total [C3H)glycogen hydrolysis.
MEASUREMENT OF NEURON‐SPECIFIC (NSE) AND NON‐NEURONAL (NNE) ISOENZYMES OF ENOLASE IN RAT, MONKEY AND HUMAN NERVOUS TISSUE
Authors: Marangos P. J. , Schmechel D. , Parma A. M. , Clark R. L. , Goodwin F. K.
Published: October 2006

Four double antibody solid‐phase radioimmunoassay systems are described for the measurement of neuron‐specific enolase (NSE) and non‐neuronal enolase (NNE) from rat, monkey and human brain tissue. NSE and NNE are antigenically distinct, making their respective assays specific. The levels of neuronal and non‐neuronal enolase (an enolase recently shown to be localized in glial cells) are determined in various regions of rat, monkey and human nervous system. Both neuronal and glial enolases are major proteins of brain tissue with each representing about 1.5% of total brain soluble protein. NSE levels are highest and NNE levels lowest in brain areas having a high proportion of grey matter, such as the cerebral cortex. The reverse is true for areas high in white matter, such as the pyramidal tract and the corpus callosum. Peripheral nervous system levels of NSE are much lower than those of brain with the spinal cord intermediate between the two.

Radioimmunological and immunocytochemical data show that neuron‐specific enolase is also present in neuroendocrine cells located in non‐nervous tissue, which include pinealocytes, parafollicular cells of the thyroid, adrenal medullary chromaffin cells, glandular cells of the pituitary and Islet of Langerhans cells in the pancreas. Unlike neurons, these cells also contain non‐neuronal enolase in high amounts.
Thiamin Deficiency in the Lamb: Changes in Thiamin Phosphate Esters in the Brain
Authors: Thornber E. J. , Dunlop R. H. , Gawthorne J. M.
Published: October 2006

: Concentrations of thiamin (unphosphorylated), thiamin monophosphate (TMP), thiamin diphosphate (TDP), and thiamin triphosphate (TTP) were measured in three regions of the brain of seven pairs of lambs. The lambs were maintained on a thiamin‐free synthetic diet for 2, 3, or 4 weeks. Controls were pair‐fed and supplemented with thiamin. The three brain regions were: (1) dorso‐lateral aspect of the cortex [common site for lesions of polioencephalomalacia (PEM)]; (2) pyriform lobe of the cortex (no PEM lesions are found here); (3) white matter of the internal capsule (no PEM lesions found here). The concentration of TTP in all three sections of brain was maintained at control values for up to 4 weeks on the thiamin‐deficient diet. TDP concentration decreased to 22% of control values in both regions of grey matter after 4 weeks on the diet. Unphosphorylated thiamin and TMP decreased to a smaller extent than TDP.
A New Class of Monoamine Oxidase Inhibitors
Authors: Vunnam R. R. , Bond D. , Schatz R. A. , Radin N. S. , Narasimhachari N.
Published: October 2006

Newly synthesized compounds have been found to inhibit mitochondrial monoamine oxidase (MAO) in mouse brain and rat liver. A series of 2‐acylamino‐3‐tert‐aminopropiophenones acted preferentially against MAO type B (2‐phenylethylamine as substrate), apparently irreversibly. 2‐Decanoylamino‐3‐morpholinopropiophenone acted similarly in vivo toward the cerebral MAO, producing a dose‐related inhibition. At high dose levels, MAO type A was also severely inhibited. The effects were produced rapidly and restoration of enzyme activity also appeared rapidly. The half‐life for MAO type A could be estimated from the rate of enzyme reappearance to be 13 h. It is suggested that the amino ketones undergo a β‐elimination reaction at the enzyme's active site, forming a reactive species (an α,β‐unsaturated ketone), which reacts covalently with a nucleophilic group of the enzyme by a Michael addition. Some other related compounds, derivatives of phenylpropane, also showed inhibitory activity against MAO, particularly against type A (serotonin as substrate). The morpholino compound might have promise as a quickly effective, short‐acting inhibitor of MAO type B.
The Characterization of the α‐Subunits of 7S Nerve Growth Factor
Authors: Stach Robert W. , Pignatti Pier F. , Baker Michael E. , Shooter Eric M.
Published: October 2006

Abstract: The molecular weight of the α‐subunit from 7S Nerve Growth Factor was found to be 26,500 by sedimentation equilibrium and by electrophoretic analysis under denaturing conditions of the native and dimethylsuberimidate cross‐linked α‐subunit. The α‐subunit, and each of the individual α‐subunits in this preparation, contained one heavy peptide chain of molecular weight 17,200 and one light peptide chain of molecular weight 9500, held together by disulfide bridges. It is likely that the charge differences between the individual α‐subunits arise from posttranslational modifications of a parent α‐subunit.
Characterization of Adenylate Cyclase Purified from Rat Brain by Hydrophobic Chromatography
Authors: Stockton Jane M. , Turner Anthony J.
Published: October 2006

Abstract. Hydrophobic chromatography of detergent‐solubilized rat brain adenylate cyclase on dodecyl‐Sepharose produced a species that was soluble in the absence of detergent and could be manipulated like a conventional hydrophilic protein. Sevenfold purification was achieved by this technique. Further purification could then be effected by affinity chromatography on ATP‐Sepharose. The purified enzyme was no longer sensitive to fluoride or guanyl nucleotides. No interaction of brain adenylate cyclase was observed with immobilized triazinyl dyes such as Cibacron Blue 3GA nor with concanavalin A‐Sepharose. The molecular weight of the fluoride‐activated catalytic complex in a freeze‐dried membrane preparation was estimated to be 133,000 by irradiation inactivation.
Muscarinic Receptors in Chromaffin Cell Cultures Mediate Enhanced Phospholipid Labeling but Not Catecholamine Secretion
Authors: Fisher Stephen K. , Holz Ronald W. , Agranoff Bernard W.
Published: October 2006

Abstract: The addition of either carbachol or muscarinic agonists to cultured bovine adrenal chromaffin cells results in a selective stimulation of phosphatidate (PhA) and phosphatidylinositol (PhI) labeling from 32Pi and [3H]glycerol that can be inhibited by the inclusion of atropine, but not d‐tubocurarine. In contrast, increased catecholamine secretion is observed on the addition of carbachol or nicotinic agonists and is inhibited by d‐tubocurarine but not by atropine. Added calcium is essential for catecholamine secretion but not for stimulated phospholipid labeling. Chelation of endogenous Ca2+ with EGTA does, however, inhibit the stimulated phospholipid labeling. These results suggest that stimulated phospholipid labeling in the bovine chromaffin cell and catecholamine secretion are separate and distinct processes.
Subunit Structure of α‐Bungarotoxin Binding Component in Mouse Brain
Authors: Seto Akiko , Arimatsu Yasuyoshi , Amano Takehiko
Published: October 2006

Abstract: The α‐bungarotoxin binding component in mouse brain was purified by affinity chromatography with toxin‐Sepharose, gel‐chromatography on Sepharose 6B, and ion‐exchange chromatography with DE52 resin. The iodinated product of the last step produced one major and one minor band on sodium dodecyl sulphate‐polyacrylamide gel electrophoresis (SDS‐PAGE). The molecular weight of the minor peak was twice as large as that of the major one. The iodinated product could bind α‐bungarotoxin, and this binding was inhibited by a nicotinic antagonist, d‐tubocurarine, which demonstrated that the iodinated product was a true α‐bungarotoxin binding component. The molecular structure of the product was analysed by cross‐linking followed by SDS‐PAGE. The results fitted the model for an α‐bungarotoxin binding component in the mouse brain composed of six identical or very similar subunits of 51,000‐52,000. One subunit carrying the binding site for toxin bound one molecule of toxin. This subunit structure of an α‐bungarotoxin binding component in the brain is discussed in comparison with that of a nicotinic acetylcholine receptor in the electric organ.
Dynorphin‐Related Opioid Peptides in the Neurointermediate Pituitary of Rats Are Not α‐N‐Acetylated
Authors: Seizinger Bernd R. , Höllt Volker , Herz Albert
Published: October 2006

Abstract: Immunoreactive dynorphin in the neurointermediate pituitary of rats was found to consist of four different molecular weight forms. The three larger molecular weight forms, with apparent molecular weights of 4800, 3200, and 1700, constituted more than 80% of the total dynorphin immunoreactivity, and each liberated leucine‐enkephalin but not α‐N‐acetyl‐leucine‐enkephalin upon enzymatic treatment with trypsin followed by carboxypeptidase B. Only a minor portion of the smallest dynorphin‐related molecular weight form, dynorphin‐(1–8), released α‐N‐acetyl‐leucine‐enkephalin upon enzymatic cleavage. This suggests that the vast majority of dynorphin‐related peptides in the rat neurointermediate pituitary is not α‐N‐acetylated. The exceptionally high opiate‐like activity of the molecular weight 1700 dynorphin suggests that this dynorphin‐related opioid peptide may constitute the major part of opioid activity in the neurointermediate pituitary of rats.
Maturation of Potassium‐Stimulated Respiration in Rat Cerebral Cortical Slices
Authors: Holtzman David , Olson James , Zamvil Scott , Nguyen Hung
Published: October 2006

Abstract: Maximal dinitrophenol‐stimulated respiration and K+‐stimulated respiration were measured polarographically in cerebral cortical slices taken from rats aged 2–60 days. Increasing K+ concentrations produced an increase in respiration in slices from animals aged 15 days and older, but not in slices from animals aged 10 days and younger. Dinitrophenol‐stimulated respiration, or the maximal respiratory capacity of the tissue, showed a similar increase between 10 and 15 days of age. At each age the maximal respiratory capacity was 6–8 ng at 0/mg protein min greater than the maximal K+‐stimulated respiration.
Characterization of Neurotransmitter Receptors in the Rat Hippocampal Formation
Authors: Dooley David J. , Bittiger Helmut
Published: October 2006

Abstract: The hippocampal formation has been extensively researched in terms of its putative neurotransmitters, anatomical connections, and behavioral relevance. An aspect of related importance is the assessment of apparent neurotransmitter receptors by using receptor binding assays. In the present study, such assays were done in vitro to investigate α1‐adrenergic, α2‐adrenergic, β‐adrenergic, muscarinic cholinergic, benzodiazepine, and opiate receptors in the rat hippocampal formation. The corresponding radioligands for these receptors were [3HH]prazosin, [3H]p‐aminoclonidine, [3H]dihydroalprenolol, [3H]quinuclidinyl benzilate, [3H]flunitrazepam, and [3H]naloxone. An analysis of the binding parameters for the ligands indicated saturable binding of a high affinity and the following rank order of maximal binding capacities: [3H]flunitrazepam > [3H]quinuclidinyl benzilate > [3H]naloxone > [3H]p‐aminoclonidine > [3Hlprazosin > [3H]dihydroalprenolol. Competition experiments with pharmacologic agonists and antagonists confirmed the specificity of each ligand. The results are integrated with information on other types of receptors and with neurotransmitter concentrations, and discussed in terms of hippocampal function.
Characterization of Glutamic Acid Decarboxylase Activity in Cerebral Blood Vessels
Authors: Hamel Edith , Krause Diana N. , Roberts Eugene
Published: October 2006

Abstract: Glutamic acid decarboxylase activity associated with cerebral blood vessels appears to be part of a specific cerebrovascular system involving γ‐aminobutyric acid. This activity was characterized kinetically and pharmacologically and compared with that in brain and several nonneuronal tissues. Formation of γ‐aminobutyric acid from [14C]glutamate was measured in a soluble extract of pia‐arachnoid blood vessels isolated from bovine brain. The vascular activity was like brain glutamate decarboxylase in that it required pyridoxal phosphate, was completely inhibited by aminooxyacetic acid, and had a similar affinity for glutamate. Cerebrovascular decarboxylase activity differed, however, from brain decarboxylase in that it was less sensitive to sulfhydryl reagents, was stimulated by 3‐mercaptopropionic and cysteic acids, and was competitively inhibited by cysteine sulfinic acid. The glutamate decarboxylase activity of the cerebral vessels was similar to that in renal cortex and mesenteric blood vessels in its responses to sulfhydryl reagents and 3‐mercaptopropionic acid. These findings are consistent with previous suggestions of a nonneuronal form of the enzyme and offer the possibility that synthesis of γ‐aminobutyric acid in cerebral blood vessels can be manipulated independently from that in neuronal tissue.
Muscarinic Receptors Modulate Dopamine‐Activated Adenylate Cyclase of Rat Striatum
Authors: Olianas Maria C. , Onali Pierluigi , Neff Norton H. , Costa Erminio
Published: October 2006

Abstract: We investigated the effect of acetylcholine (ACh) on the activation of adenylate cyclase by dopamine (DA) in a lysed synaptosomal preparation from rat striatum. ACh reduced both basal and the DA‐activated adenylate cyclase with an apparent IC50 of −1 μM. From a kinetic analysis it appeared that ACh reduced the Vmax for activation by DA but not the activation constant for DA. For most preparations the Vmax was reduced by 3040%. The presence of atropine did not affect the activation of the enzyme by DA but it blocked the inhibition by ACh. Following 6‐hydroxydopamine lesion of the nigrostriatal pathway, the enzyme became supersensitive to activation by DA and also more sensitive to inhibition by ACh. Inhibition of adenylate cyclase by ACh appeared to be rather specific for activation by DA, as ACh had no effect on activation of adenylate cyclase by the adenosine analogue N6‐(L‐2‐phenylisopropyI)adenosine. These results indicate that some striatal muscarinic and dopaminergic receptors are probably coupled to the same adenylate cyclase domain. Moreover, they suggest a biochemical model for the dynamic balance of cholinergic and dopaminergic neurons that innervate the striatum.
Epinephrine: A Potential Neurotransmitter in Retina
Authors: Hadjiconstantinou Maria , Cohen Joseph , Neff Norton H.
Published: October 2006

Abstract: Dopamine (DA), norepinephrine (NE), and epinephrine (EPI) are present in rat retina. DA is the major catecholamine, whereas NE and EPI represent −5% of the DA content. DA is contained in a subpopulation of amacrine cells and has been the subject of numerous studies. We investigated the origin and properties of NE and EPI in retina. Following superior cervical ganglionectomy, there was a decrease in NE content, but no decrease in EPI or phenylethanolamine‐N‐methyltransferase (PNMT) activity. PNMT in retina has many of the substrate‐specificity and inhibitor‐sensitivity characteristics of other tissues. Enzyme activity is enhanced in newborn rats by treatment with dexamethasone. Exposure to a lighted environment increases retinal EPI in normal and superior cervical ganglionectomized rats. EPI content increased for more than 2 h in a lighted environment. We conclude that most of the NE is contained within the sympathetic neurons that innervate the eye from the superior cervical ganglion, whereas EPI is contained in retinal elements that are responsive to photic stimulation.
Neuronal [3H]Benzodiazepine Binding and Levels of GABA, Glutamate, and Taurine Are Normal in Huntington's Disease Cerebellum
Authors: Kish Stephen J. , Shannak Kathleen S. , Perry Thomas L. , Hornykiewicz Oleh
Published: October 2006

Abstract: Alterations in one subunit of the proposed GABA receptor complex, namely, the GABA receptor, have been observed in Huntington's disease cerebellum. We measured binding to a second subunit, the benzodiazepine binding site, in the autopsied cerebellum of 12 patients dying with adult‐onset Huntington's disease. Neuronal benzodiazepine ([3H]flunitrazepam) binding density (Bmax) and affinity in cerebellar cortex of the Huntington's disease patients were not significantly different from control values. Similarly, maximal GABA stimulation of benzodiazepine binding was normal in the Huntington's disease cerebellum. In addition, no significant changes were observed in the concentrations of GABA, glutamate, and taurine in cerebellar cortex, nor of GABA in the dentate nucleus.
Species Heterogeneity of Pineal Hydroxyindole‐O‐Methyltransferase
Authors: Nakane Masaki , Yokoyama Emiko , Deguchi Takeo
Published: October 2006

Abstract: Hydroxyindole‐O‐methyltransferase was purified from bovine and chicken pineal glands to apparent homogeneity and their properties were compared. The purified enzymes from both pineal glands differed in electrophoretic mobility and isoelectric point. Sodium dodecyl sulfate gel electrophoresis revealed that hydroxyindole‐O‐methyltransferase of both bovine and chicken pineals was a dimer consisting of a subunit of molecular weight 39,000. The two enzymes also differed in substrate specificity. Bovine hydroxyindole‐O‐methyltransferase showed a high specificity toward N‐acetylserotonin, whereas chicken enzyme methylated N‐acetylserotonin and, to some extent, serotonin and bufotenine. The methylation of the three substrates was probably catalyzed by the same enzyme of chicken pineal, because the ratio of substrate availability did not change throughout the purification steps. Using the purified enzymes, we prepared antibody to both bovine and chicken hydroxyindole‐O‐methyltransferase. The antibody to bovine enzyme cross‐reacted with both avian and mammalian enzymes, whereas the antibody to chicken hydroxyindole‐O‐methyltransferase reacted with avian enzymes, but far less with mammalian enzymes, indicating an immunochemical difference between avian and mammalian hydroxyindole‐O‐methyltransferase. The results suggest that the properties of hydroxyindole‐O‐methyltransferase have changed during the evolutionary development of the pineal glands.
Inhibition of Synaptosomal Neurotransmitter Uptake by Hallucinogens
Authors: Whipple Michael R. , Reinecke Manfred G. , Gage Fred H.
Published: October 2006

The effect of 13 hallucinogens on the uptake of serotonin and norepinephrine into hippocampal synaptosomes and of serotonin and dopamine into caudate synaptosomes was found to be inhibitory, except for lysergic acid diethylamide and 2‐bromolysergic acid diethylamide, which were inactive. The indoleal‐kylamines were generally more potent than the phenylethylamines. The reported inhibition of uptake of serotonin by 5‐methoxy‐N,N‐dimethyltryptamine and lysergic acid diethylamide into whole brain synaptosomes was not reproducible at concentrations 102 to 104 times higher than those stated in the literature.
Differential Effects of Fluoronorepinephrines on Phosphatidylinositol Turnover in Rat Pinealocytes
Authors: Hauser George , Kirk Kenneth L. , Parks Joe M.
Published: October 2006

Abstract: (±)‐Norepinephrines (NAs), substituted with fluorine at positions 2, 5, and 6 of the ring, were compared with the unsubstituted compound with respect to their capacity for eliciting increased incorporation of [32P]orthophosphate into phosphatidylinositol of pinealocytes. 5F‐NA and 6F‐NA were approximately equipotent with NA, whereas 2F‐NA required a higher concentration and gave lower maximum stimulation. Inhibition of these effects by prazosin confirmed the participation of α1‐adrenergic receptors. The results are comparable with those reported for α1 adrenergic receptor‐mediated events in other systems and different from the β‐adren‐ergic receptor‐mediated elevation of cyclic AMP in pinealocytes. These and earlier results emphasize the importance of the hydroxyl group at position 3 of the ring and at the β‐position of the side chain in catecholamine activation of the pineal α‐adrenergic receptors, which are involved in alterations of phospholipid metabolism.
Changes in Levels of Dopamine and Tyramine in the Rat Caudate Nucleus Following Alterations of Impulse Flow in the Nigrostriatal Pathway
Authors: Jones R. S. G. , Juorio A. V. , Boulton A. A.
Published: October 2006

Abstract: Following electrical stimulation of the substantia nigra for 1 h there was a substantial increase in dopamine (DA) turnover in the rat caudate nucleus evidenced by an increase in its acid metabolite homovanillic acid (HVA). Concurrently there was an increase in striatal m‐tyramine (mTA) and a substantial decrease in p‐tyramine (pTA). Lesioning the substantia nigra to decrease impulse flow resulted in a buildup of striatal DA and mTA, but again a decrease in pTA. Following pre‐treatment with a tyrosine hydroxylase inhibitor, the effects of stimulation of the nigra on mTA were reversed, there being a significant decrease in this amine. The decrease of pTA in response was partially prevented by tyrosine hydroxylase inhibition. The effects of stimulation or substantia nigra lesions on pTA levels were reversed, however, by tyrosine hydroxylase inhibition, a significant increase in this amine being recorded. mTA and DA levels were largely unaffected by a combination of lesion and tyrosine hydroxylase inhibition. The results provide insight into the possible biosynthetic interrelationships between DA and the tyramine isomers in the rat caudate nucleus.
Blockade by Neurotransmitter Antagonists of Veratridine‐Activated Ion Channels in Neuronal Cell Lines
Authors: Reiser Georg , Günther Andrea , Hamprecht Bernd
Published: October 2006

Abstract: The voltage‐dependent Na+ ionophore of various neuronal cells is permeable not only to Na+ ions but also to guanidinium ions. Therefore, the veratridine‐(or aconitine‐) stimulated influx of [14C]guanidinium in neuroblastoma × glioma hybrid cells was measured to characterize the Na+ ionophore of these cells. Half‐maximal stimulation of guanidinium uptake was seen at 30 μM veratridine. At 1 mM guanidinium, the veratridine‐stimulated uptake of guanidinium was lowered to 50% by approximately 60 mM Li+, Na+, or K+ and by a few millimolar Mn2+, Co2+, or Ni2+. The basal, as well as the veratridine‐stimulated, uptake of guanidinium was inhibited by the cholinergic antagonists (+)‐tubocurarine (Ki= 50 to 500 nM) and atropine (Ki= 5 to 30 μM) and the adrenergic antagonists phentolamine (Ki= 5 μM) and propranolol (Ki= 60 μM). The specificity of the inhibitory effects of these agents is stressed by the ineffectiveness of various other neurotransmitter antagonists. However, the corresponding ionophore in neuroblastoma cells (clone N1E‐115) seems to be regulated differently. While phentolamine and propranolol inhibit the veratridine‐activated uptake as in the hybrid cells, (+)‐tubocurarine and atropine exert only a slight effect.
Histamine Stimulation of Inositol 1‐Phosphate Accumulation in Lithium‐Treated Slices from Regions of Guinea Pig Brain
Authors: Daum P. R. , Downes C. P. , Young J. M.
Published: October 2006

Abstract: Histamine stimulated the accumulation of [3H]inositol 1‐phosphate in the presence of 10 mM LiCl in [3H]inositol‐loaded tissue slices from several regions of guinea pig brain. The level of [3H]inositol 1‐phosphate increased approximately linearly, after an initial lag period, up to a time of 120 mm. In the absence of lithium ions the accumulation of the 1‐phosphate stimulated by histamine in cerebral cortical and hippocampal slices was markedly reduced. Lithium ions had much less effect on the response to histamine in cerebellar slices. The characteristics of the response to histamine were consistent with mediation by H1, receptors, and the affinity constants derived for mepyramine (2.3 × 109M−1) and methapyrilene(1.8 × 109M−1) were similar to those reported from measurements on other H1 responses in the guinea pig. The EC50 for histamine was similar in cerebellum, cerebral cortex, hippocampus, and hypothalamus. The position of the dose‐response curve for histamine in cerebral cortical slices was similar to ‐that of the curve for the receptor binding of histamine deduced from histamine inhibition of [3H]mepyramine binding.