bluuebunny/crossref_metadata_2025 huggingface dataset:
THE LOCALIZATION OF MITOCHONDRIAL NADP‐DEPENDENT ISOCITRATE DEHYDROGENASE IN NORMAL AND HYPOXIC CONDITIONS
Authors: GROMEK A. , PASTUSZKO A.
Published: October 2006

Abstract—

NADP‐dependent isocitrate dehydrogenase is localized in both external and internal membranes and in the mitochondrial matrix from brains of adult and newborn animals. Electrophoretic studies indicate that the mitochondrial enzyme occurs in the form of two isoenzymes; the isoenzyme of the external membranes behaves similarly to that of the cytoplasm. Ischaemia in adult animals results in a decrease in enzyme specific activity, particularly in external membranes, while in the mitochondrial fraction of the newborn the activity of the enzyme increased.
SUBCELLULAR LOCALIZATION OF α‐MELANOCYTE‐STIMULATING HORMONE IN THE RAT HYPOTHALAMUS1
Authors: BARNEA AYALLA , OLIVER CHARLES , PORTER JOHN C.
Published: October 2006

Abstract—

Homogenates of male rat hypothalami were fractionated by means of differential centrifugation, and α‐melanocyte‐stimulating hormone (α‐MSH) in the various fractions was quantified by radioimmunoassay. Of the total quantity of α‐MSH in the homogenate, 36% was recovered in the 11,500 g pellet and 31% sedimented between 11,500 and 105,000 g. α‐MSH was not detected in the 105,000 g supernatant fluid. When the 900 g supernatant fluid was fractionated on continuous sucrose density gradients at non‐equilibrium conditions, two populations of particles containing α‐MSH were observed. When fractionated at equilibrium conditions, the two populations were recovered in a single band. These sedimentation characteristics indicate that the particles that contain α‐MSH differ in size but are similar in density. After hypo‐osmotic shock, the large particles containing α‐MSH were not demonstrable, whereas the small particles appeared to be resistant to such treatment. In their sedimentation, the particles containing α‐MSH were indistinguishable from particles containing thyrotropin releasing hormone (TRH) but were separable from those that contained luteinizing hormone releasing hormone (LHRH). It is suggested that the large particles containing α‐MSH are synaptosomes.
MUSCARINIC REGULATION OF cAMP IN MOUSE NEUROBLASTOMA
Authors: BLUME A. J. , CHEN C. , FOSTER C. J.
Published: October 2006

Abstract—

The neurotransmitter acetylcholine regulates cAMP concentrations in mouse neuroblastoma cells (clone NS20). In these cells, the action of acetylcholine appears to be specific: it does not alter basal concentrations of cAMP, but prevents the elevation of cAMP which is mediated by either adenosine or prostaglandin E1. The receptor for acetylcholine which is involved in this phenomenon has been identified as muscarinic. Pilocarpine and carbamylcholine, but not acetate or choline, will substitute for acetylcholine. Furthermore, the action of 10 μM‐carbbamylcholine is blocked by ≥ nM concentrations of atropine, isopropamide or 3‐quinuclidinylbenzilate, but not by mM concentrations of d‐tubocurarine or hexamethonium.

Of eight cholinergic antagonists tested, decamethonium and succinylcholine were the only two which were able to substitute for acetylcholine. These two antagonists are known to cause depolarization of post‐synaptic cells. Decamethonium and succinylcholine appear to interact with the same muscarinic receptor, as their actions are also blockèd by low concentrations of 3‐quinuclidinylbenzilate. In addition to these two depolarizing antagonists, the ionophores, valinomycin, A23187 and X537A, were also found to prevent elevation of cAMP concentrations. The involvement of specific membrane depolarization as being the active agent by which acetylcholine inhibits elevation of cAMP concentrations is discussed.
STUDIES ON FORMATION OF γ‐GLUTAMYLAMINES IN RAT BRAIN AND THEIR SYNTHETIC AND CATABOLIC ENZYMES
Authors: TSUJI M. , MATSUOKA Y. , NAKAJIMA T.
Published: October 2006

Abstract—

γ‐Glutamylation of p‐tyramine, noradrenaline, dopamine and serotonin in rat brains was demonstrated by intraventricular injections of the radioactive amines and isolation of the γ‐glutamylamines from the acidic extract of the rat brains. Formation of these γ‐glutamylamines was proved to be catalysed by γ‐glutamyltranspeptidase prepared from both rat kidney and brain. However, these compounds were degraded by γ‐glutamylcyclotransferase of rat brain, but not by the emzyme of rat kidney.
OCCURRENCE OF ALKANES IN BRAIN MYELIN. COMPARISON BETWEEN NORMAL AND QUAKING MOUSE
Authors: BOURRE J. M. , CASSAGNE C. , LARROUQUERE‐REGNIER S. , DARRIET D.
Published: October 2006

Abstract—

Alkanes, a new class of neurolipid, were found in mouse brain, the level being reduced in the Quaking mutant. These hydrocarbons are concentrated in myelin; minor amounts being found in microsomes, mitochondria and synaptosomes. The average recovery is 7.1 μg/mg in normal myelin, 2.2 in the Quaking myelin. The distribution pattern of these alkanes was determined by gas liquid chromatography and was found to differ in normal and Quaking myelin; the hydrocarbons consist mainly of n‐alkanes ranging from C21 to C32 with even and odd aliphatic chains.
EFFECT OF DIETARY HISTIDINE ON OLFACTION, AND RAT BRAIN AND MUSCLE CONCENTRATION OF HISTIDINE‐CONTAINING DIPEPTIDES1
Authors: QUINN MICHAEL R. , FISHER HANS
Published: October 2006

Abstract—

Young adult male rats were fed three diets; one was devoid of histidine (HF), the second supplied the maintenance requirement (M, 3.7% protein, 0.07% histidine), and the third provided an optimal amount of histidine for growth (G, 10.0% protein, 0.21% histidine). The M diet was pair‐fed with the HF diet. After an 11 weeks experimental period, some HF animals were given the M diet for an 11 day repletion period. On the HF diet carnosine in the olfactory bulb and pectoral muscle, homocarnosine in whole brain and hemoglobin were sharply and significantly reduced in concentration below the levels found in the M and G groups. During the 11 day repletion period all concentrations except for hemoglobin returned to normal. Comparison of olfactory ability between M and HF rats showed no significant difference indicating that if carnosine is involved in olfaction, the amount required must be very small. Restricted food intake had no apparent effect on the concentration of histidine‐containing dipeptides but did influence hemoglobin concentration. The HF rats appeared to exhibit an altered state of emotionality compared to either of the other two treatment groups.
ELEVATION IN RAT BRAIN HISTAMINE CONTENT AFTER FOCUSED MICROWAVE IRRADIATION1
Authors: Hough Lindsay B. , Domino Edward F.
Published: October 2006

Abstract— —Microwave irradiation focused on the head of small rodents is now widely used as a means of more accurately measuring acetylcholine, choline, cyclic AMP, and several other important brain constituents. Because of its probable neurotransmitter role and rapid turnover, a similar approach was taken to study brain histamine. Histamine was measured by a modified radio‐enzymatic method and was found to be nearly tripled in brains from microwave treated rats, compared to decapitation controls (124 vs 42 ng/g). Possible explanations include a microwave‐induced inactivation of histamine breakdown, a microwave‐induced redistribution of previously unmeasured histamine, and microwave‐induced histidine decarboxylation. Brain histamine remained unchanged up to 30 min after decapitation and microwave heated brains from decapitated rats also had elevated histamine levels, indicating that brain histamine levels in decapitated rats do not represent the remainder of a rapidly depleting pool. No evidence for previously unmeasured histamine was found. Furthermore, microwave irradiation did not enhance the formation of [3H]histamine after intraventricular [3H]histidine administration, indicating a lack of microwave‐induced histidine decarboxylation. It is concluded that the elevation in rat brain histamine after focused microwave irradiation is probably not artifactual, although the mechanism responsible for this phenomenon remains obscure.
A BRAIN‐SPECIFIC PROTEIN FROM OCTOPUS VULGARIS, LAM
Authors: Giuditta A. , Moore B. W. , Prozzo Nicola
Published: October 2006

Abstract— Several major brain‐specific proteins have been detected in cephalopods by electrophoretic analysis of the soluble proteins extracted from the optic lobes and other organs of octopus and by 2‐dimensional fractionation of the soluble proteins from optic lobes and hepatopancreases of octopus and squid. One of the brain‐specific proteins from octopus, identified as 0‐1, has been purified by chromatography on DEAE‐cellulose, Sephadex G‐150, and DEAE‐Sephadex. The protein appears to be pure on the basis of several physicochemical criteria. Amino acid analysis indicates a high content of glutamic and aspartic acids or their amides (or both) and the lack of tryptophan. A molecular weight of 17,000 has been calculated from sodium dodecyl sulphate‐gel electrophoresis, gel filtration and ultracentrifugation analysis. The preparation of a specific rabbit antiserum against 0‐1 has allowed its determination by agar immunodiffusion and complement fixation techniques. With the latter procedure it has been shown that the protein is absent outside the nervous system, is present in a concentration of several mg/g wet weight in octopus brain and is widely distributed within the octopus central and peripheral nervous system and in several molluscan species. It is also present in optic lobes of octopus at early stages of development.
MEASUREMENT OF BRAIN PROTEIN TURNOVER WITH [14C]SODIUM BICARBONATE1
Authors: Chee Po Yok , Dahl June L.
Published: October 2006

Abstract— Protein turnover in rat brain was measured over a period of 30 days by following the decay in specific radioactivity of acidic amino acids in proteins labelled by a single intraperitoneal injection of [14C]NaHCO3. Two major populations of brain proteins can be identified from the resultant non‐linear decay curve—one with an average half‐life of 4 days and another with an average half‐life of 12 days. The half‐lives of total brain, mitochondrial, microsomal and soluble proteins determined over a period of 5 days were 3.4, 5.8, 2.8, and 2.6 days, respectively. Turnover of these same brain subcellular fractions was also measured by continuous infusion of [14C]tyrosine. The estimated half‐lives were in close agreement with those obtained from the 5 day measurement of radioactive decay following a pulse label of [14C]NaHCO3.
STUDIES ON THE MONOAMINE OXIDASE OF MONKEY BRAIN
Authors: Oommen Anna , Balasubramanian A. S.
Published: October 2006

Abstract— A study of the enzyme monoamine oxidase (MAO) was carried out in the monkey brain. From the monkey brain mitochondrial fraction a lysolecithin‐soluble form of the enzyme (MAOs and an insoluble form (MAOp) were isolated. The latter required freezing, thawing and sonication for solubilization. Both these forms of MAO had identical electrophoretic mobilities, a pH optimum of 7 and comparable thermal stabilities. The enzyme which could not be solubilized and which remained membrane‐bound also gave the same pH optimum of 7 and a similar thermal stability profile. Both MAOs and MAOp had comparable Km values of 2.2 × 10−5 m and 5.0 ×105‐ m respectively when using tyramine as substrate and 7.4 ×−5 M and 7.7 × 10−5 m respectively with benzylamine as substrate. The Km values of the membrane‐bound enzyme were 1.0 × 10″5m with tyramine as substrate 2.5 × m with benzylarnine as substrate. The MAO inhibitors, tranylcypromine, isocarboxazid and iproniazid inhibited both MAOs and MAOp to approximately the same extent. The extent of inhibition of the membrane‐bound enzyme however, was relatively different with all three inhibitors. Immunodiffu‐sion techniques using anti‐MAOp indicated the immunological identity among MAOp, MAOs and the mitochondrial fraction. Substrate specificity and substrate competition experiments as well as the use of the selective inhibitor pargyline indicated the presence of both the ‘A’ and ‘B’ type of activity in the MAO isolated from monkey brain.
THE EFFECT OF GROWTH AND DEVELOPMENT ON THE PHOSPHOLIPIDS OF THE HUMAN BRAIN
Authors: Yusuf H. K. M. , Dickerson J. W. T.
Published: October 2006

Abstract— The phospholipid content and composition of the different regions of the developing human brain were studied. Brains from 25 fetuses and 9 infants, aged 13 weeks gestation to 26 months, were analysed. The concentration of total lipid‐P was highest in the brain stem and lowest in the cerebellum at any age. Compared with the forebrain or brain stem, the cerebellum had a sharp phospholipid growth spurt between 3 months before and 6 months after birth. Before birth, the phospholipid pattern was similar in each part of the brain, with choline phosphoglycerides as the major phospholipid. After birth, the pattern in the brain stem changed further and ethanolamine phosphoglycerides became the dominant phospholipid, while in the other two there was little change. In all parts of the brain the proportion of sphingomyelin increased. The relative proportion of serine and inositol phosphoglycerides remained almost constant throughout the whole period of development. The possible significances of the changes in the phospholipids in neurological development are discussed.
SYNAPTOSOMAL TYROSINE HYDROXYLATION: AFFINITY FOR OXYGEN
Authors: Davis J. N.
Published: October 2006

Abstract— Crude striatal synaptosomes were used to determine the affinity of brain tyrosine 3‐mono oxygenase for oxygen. The rate of tyrosine hydroxylation was determined at several different oxygen concentrations using L‐[14C]tyrosine as substrate and measuring the [14C]DOPA formed in the presence of a decarboxylase inhibitor. The accumulation of [14C]tyrosine by synaptosomes was unaffected by incubation in nitrogen or 2.3% oxygen. Preincubation in nitrogen for up to 4 h did not impair the ability of synaptosomes to hydroxylate tyrosine when returned to air. Furthermore, pre‐incubation in either nitrogen or air produced similar changes in the ultrastructural appearance of the synaptosomes and mitochondria in the crude preparation used in these studies. Thus tyrosine hydroxylation in these synaptosomes appeared to reflect tyrosine 3‐mono oxygenase activity over a range of oxygen concentrations. The apparent Km for oxygen was 2 × 10−5 at pH 6.7 and 7.4. The apparent Km was not significantly altered by the addition of Ca2+, and was slightly increased in the presence of N6‐mono‐butyryl cyclic AMP or high K+. These data are consistent with the hypothesis that the availability of oxygen may limit catecholamine synthesis in the intact rat brain.
SEPARATION OF ACETYLCHOLINE AND CATECHOLAMINE CONTAINING SYNAPTIC VESICLES FROM BRAIN CORTEX
Authors: Nagy Agnes , Várady Gy. , Joó F. , Rakonczay Z. , Pilc A.
Published: October 2006

Abstract— Synaptic vesicles were prepared from guinea‐pig cerebral cortex on a continuous D2O‐H2O(1:1)‐sucrose gradient and purified in the presence of 1 mm‐EGTA by chromatography on columns of glass beads of controlled pore size. As markers, endogenous ACh, NA, dopamine and DβH were measured.

Two distinct populations of synaptic vesicles were recognized between the layers of 0.2–0.3 m‐ and 0.3–0.5 m‐sucrose, which differed from each other both in electron microscopic appearance and transmitter content. The less dense vesicles had a much higher ACh content than the more dense vesicles which were composed mainly of somewhat larger particles with high NA and dopamine content. DβH was found to be present in substantial amounts in guinea‐pig cortex and was located in the synaptic vesicle fractions having high CA content.

After glass bead chromatography the vesicle preparations were morphologically homogeneous, practically free from other subcellular elements and were contaminated with each other by not more than 10%

The yields were 0.2 and 0.1 mg protein g cortex−1 tissue for ‘cholinergic’ and ‘adrenergic’ vesicle preparations, respectively.
ACTIVE UPTAKE OF 45Ca BY A MICROSOMAL FRACTION PREPARED FROM RAT DORSAL ROOTS
Authors: Eroglu Lutfiye , Keen P.
Published: October 2006

Abstract— A microsomal fraction prepared from rat dorsal spinal nerve roots accumulated 45Ca by a temperature–and ATP‐dependent mechanism. Uptake, which was maximal at pH 7.2–7.4, was potentiated 4‐fold by 8 mm‐oxalate and was linear over a 20 min incubation period. Ca uptake was not inhibited by sodium azide or by oligomycin and only slightly by ruthenium red suggesting that it was not of mitochondrial origin. On a sucrose density gradient the microsomal fraction equilibrated at between 0.25 m‐ and 0.65 m‐sucrose but, using a discontinuous gradient over this range, no fraction enriched in Ca‐accumulating activity could be separated. The possibility is discussed that the Ca‐accumulating microsomes may be derived from smooth endoplasmic reticulum.
PURIFICATION OF BOVINE PINEAL HYDROXYINDOLE O‐methylTRANSFERASE BY IMMUNOADSORPTION CHROMATOGRAPHY
Authors: Kuwano R. , Yoshida Y. , Takahashi Y.
Published: October 2006

A procedure is described for the use of immunoadsorption chromatography of hydroxyindole O‐methyltransferase (HIOMT). HIOMT was purified from bovine pineal extract by affinity chromatography on immunoglobulins (Ig)‐Sepharose. The overall purification was about 45‐fold; the yield was 84%. This enzyme constitutes about 2.0% of the soluble proteins in the pineal gland. The enzyme represented a single precipitin line on Ouchterlony double diffusion plate and immunoelectrophoresis. Ultracentrifugation analysis indicated the existence of molecular aggregates of enzyme and disc gel electrophoresis showed one main protein band and several minor bands. However sodium dodecyl sulphate (SDS) gel electrophoresis showed a single protein band with subunit molecular weight 38,000 demonstrating bovine pineal HIOMT to be polymer enzyme of a single subunit. The properties of the purified enzyme including disc gel electrophoretic pattern, the effect of pH, chemicals and substrates and immunological properties were identical with those of the crude enzyme.
MOUSE BRAIN TYROSINE HYDROXYLASE AND GLUTAMIC ACID DECARBOXYLASE FOLLOWING TREATMENT WITH ADRENOCORTICOTROPHIC HORMONE, VASOPRESSIN OR CORTICOSTERONE
Authors: Dunn Adrian J. , Gildersleeve Nancy B. , Gray Harry E.
Published: October 2006

The activities of tyrosine hydroxylase (TH) and glutamic acid decarboxylase (GAD) from several mouse brain regions were assayed following repeated administration of adrenocorticotrophic hormone (ACTH), lysine vasopressin (LVP) or corticosterone. Although similar treatments with ACTH have been shown to result in changes of catecholamine turnover and GABA content, no changes in the activity of either TH or GAD were observed in any brain region. Likewise LVP had no effect on either enzyme. Since the assays for TH were performed with concentrations of tyrosine and tetrahydrobiopterin cofactor below their respective Michaelis constants, this suggests that the changes of catecholamine turnover are not mediated by changes of TH activity. Twice daily corticosterone adrninistration for four days increased TH activity in the hypothalamus but not in any other brain region.
FURTHER EVALUATION OF POLYPEPTIDE SYNTHESIS IN CEREBRAL ANOXIA, HYPOXIA AND ISCHEMIA
Authors: Morimoto. Kazuyoshi , Brengman Joan , Yanagihara Takehiko
Published: October 2006

The alteration of polypeptide synthesis was evaluated with microsomes isolated from anoxic rabbit, hypoxic rat and ischemic gerbil brains to estimate the extent of functional or structural changes in polyribosomes in situ and the extent of artifact during tissue preparation. By using two‐stage experimentation with combination of control and pathological microsomes and supernatant, it was found that the previously observed effects on microsomal or polyribosomal polypeptide synthesis in the above pathophysiological conditions were mainly the reflection of the alteration of polyribosomes in situ rather than the artifact during tissue preparation by degradative processes. In support of this finding. the use of inhibitors of degradative enzymes did not significantly protect microsomes either in normal or in pathological conditions. It was noted that the decline of tissue pH, to a certain extent, could be correlated with dysfunction of polyribosomes both in situ and during tissue preparation in cerebral hypoxia and anoxia. Since there is little change in ATP level, it was postulated that the alteration of pH in situ is responsible for the observed suppression of polypeptide synthesis in vitro at least in cerebral hypoxia. This hypothesis was supported by the subsequent experiments with incubation of brain slices and homogenization of brain tissue under various pH. It was emphasized that the environmental biochemical elements surrounding polyribosomes in cytoplasm should be evaluated as possible contributing factors for polyribosomal dysfunction in such pathological conditions as cerebral anoxia, hypoxia or ischemia if the alteration of energy state does not explain the phenomenon entirely.
THE EFFECT OF MORPHINE TOLERANCE and DEPENDENCE ON CELL FREE PROTEIN SYNTHESIS1
Authors: Rederick F , Craves B. , Loh Horace H. , Meyerhoff James L.
Published: October 2006

A cell free system consisting of polyribosomes and pH 5 factors of the cytosol was isolated from mouse brain. This system actively promoted the incorporation of radiolabeled amino acids into protein in vitro. Addition of exogenous morphine to a cell free protein synthetic system isolated from chronically morphinized, placebo treated, or naive mouse brain had no effect on the relative synthetic capacity of the system. In addition, morphine did not alter the response to a synthetic mRNA, polyuridylic acid. However, both the polyribosomes and pH 5 factors isolated from chronically morphinized mouse brain were more effective in promoting amino acid incorporation into protein relative to the corresponding fractions from placebo treated mice. Acrylamide gel electrophoresis of the proteins in the incubation mixture showed the increased amino acid incorporation was the result of a general quantitative increase in the specific activity of all of the proteins synthesized by the cell free system.
STUDIES ON THE REGULATION OF GABA SYNTHESIS: SUBSTRATE‐PROMOTED DISSOCIATION OF PYRIDOXAL‐5′‐PHOSPHATE FROM GAD
Authors: Miller L. P. , Martin D. L. , Mazumder A. , Walters J. R.
Published: October 2006

Abstract—

The association between glutamate decarboxylase (GAD) and its cofactor, pyridoxal‐5′‐phos‐phate (pyridoxal‐P), was studied using 20,0000 supernatant of rat brain. In this preparation GAD required added pyridoxal‐P to maintain a linear reaction rate beyond 5 min of incubation. Following exhaustive dialysis the enzyme was more than 83% saturated with cofactor indicating that the cofactor was tightly bound to the enzyme. When incubations were performed in the presence of glutamate and without added pyridoxal‐P there was a progressive inactivation of the enzyme which was dependent on the glutamate concentration. This lost activity was almost completely recovered by addition of pyridoxal‐P to the dialyzed glutamate‐inactivated enzyme. The results suggest that glutamate inactivates GAD by promoting the dissociation of pyridoxal‐P from the enzyme thereby producing inactive apoen‐zyme which can be reactivated by combining with available pyridoxal‐P. This interpretation is supported by the finding that progress curves for the reaction were accurately described over a 30 min incubation period and 10‐fold glutamate concentration range by an integrated rate equation which takes the glutamate‐promoted dissociation of cofactor into account. The progressive inactivation could not be attributed to denaturation of the enzyme, impurities in the substrate, effects of pH, depletion of substrate, protein concentration, sulfhydryl reagents or product inhibition. The results presented here also show that certain precautions must be adopted to accurately measure GAD activity in the absence of added pyridoxal‐P as has been widely done in studies of drug action. Specifically, measurements must be made at short times of incubation and low concentrations of glutamate to minimize the glutamate‐promoted inactivation of the enzyme.
IMMUNOCHEMICAL AND BIOCHEMICAL STUDIES DEMONSTRATING THE IDENTITY OF A BOVINE SPINAL CORD PROTEIN (SCP) AND A BASIC PROTEIN OF BOVINE PERIPHERAL MYELIN (BF)
Authors: Deibler Gladys E. , Driscoll Bernard F. , Kies Marian W.
Published: October 2006

Abstract—

A protein extracted from bovine peripheral myelin (BF) and a protein extracted from bovine spinal cord (SCP) have been shown to be identical: the proteins cross‐react immunochemicaliy with each other but not with highly purified CNS myelin basic protein. Neither BF nor SCP have anti‐encephalitogenic activity. Their electrophoretic behavior is the same at three different pH values. Their apparent molecular weight by sodium dodecyl sulfate‐gel electrophoresis is 13,800 ± 550. The amino acid compositions of the proteins are essentially identical. BF and SCP each contain 2 cysteine residues and have valine at the C terminus. The 23 major tryptic peptides are identical on peptide maps. Circular dichroic analyses yield essentially identical curves, which, when computed by best‐fit curve analysis, indicate that each has 0%α helix and a large percentage of β structure.
PROPERTIES AND REGIONAL DISTRIBUTION OF TRYPTOPHAN HYDROXYLASE IN THE CHICKEN BRAIN
Authors: Mclennan I. S. , Lees G. J.
Published: October 2006

Abstract—

Tryptophan hydroxylase in young chicken brain had a pH optimum of 7.5–8, depending on the buffer used. It had apparent Km values for tryptophan and tetrahydrobiopterin of 49 μM and 32 μM respectively. The enzyme in chicken brain, but not rat brain, was cold‐shock labile but was stable for up to 4 days at — 20°C. Lability was observed both in tissues and homogenates of these tissues subjected to cold shock, but the extent of loss of activity varied between brain regions. Supernatant fractions did not lose activity after cold shock. The highest level of tryptophan hydroxylase was found in the rostral region of the chicken brainstem. High levels were also found in the caudal region of the brainstem, the midbrain, thalamus, caudate and cerebral cortex. The cerebellum and optic chiasma contained only traces of activity.
CYCLIC NUCLEOTIDE LEVELS IN NORMAL AND BIOLOGICALLY FRACTIONATED MOUSE RETINA: EFFECTS OF LIGHT AND DARK ADAPTATION
Authors: DeVries G. W. , Cohen A. I. , Hall I. A. , Ferrendelli J. A.
Published: October 2006

Abstract— The content of cyclic AMP and cyclic GMP was measured in whole eyes and in normal retinas from C57BL(6)J mice, in receptorless retinas from congenic mice homozygous for the receptor dystrophy gene (rd/rd), and in retinas from mice treated postnatally with monosodium glutamate. Normal retinas contain approx 320 μg of protein: dystrophic (rd/rd) retinas contain approx 110μg of protein, lack rods but possess some surviving cone somata and terminals: glutamate‐modified retinas contain approx 200 μg of protein and have both a reduced area and thickness with a marked deficiency of ganglion cells and amacrine cells. In normal mice, more than 90% of the cyclic GMP, but only 607, of the cyclic AMP of the whole eye was in the retina. In normal dark‐adapted retinas isolated under dim red light cyclic AMP and cyclic GMP content was 4.1 and 20.2pmol/retina, respectively. The content of both cyclic AMP and cyclic GMP was 40% less, 2.5 and 11.5pmol/retina, respectively, in light‐adapted retinas. In dark‐adapted retinas isolated under infra‐red light, cyclic AMP content was 40%, higher than that in retinas isolated under dim red light; cyclic GMP content was the same under these two conditions. Receptorless retinas contained approx 50% as much cyclic AMP and only 1‐2% as much cyclic GMP as normal retinas. Although glutamate‐modified retinas also had approx 50% as much cyclic AMP, they contained 60‐85%, as much cyclic GMP as normal retinas. Light decreased by 30‐50% levels of both cyclic AMP and cyclic GMP in glutamate‐modified retinas, but only reduced cyclic nucleotide levels in receptorless retinas by 20%.

These data indicate that 95% or more of the cyclic GMP is in photoreceptor cells, whereas cyclic AMP is more evenly distributed throughout the retina. In addition, both cyclic AMP and cyclic GMP levels are influenced by light‐ and dark‐adaptation.
INDUCED ACETYLCHOLINE RELEASE FROM ACTIVE PURELY CHOLINERGIC TORPEDO SYNAPTOSOMES1
Authors: Michaelson D. M. , Sokolovsky M.
Published: October 2006

Abstract—

Viablse, purely cholinergic synaptosomes were prepared from the electric organ of Torpedo ocellata and partially purified by differential and sucrose density centrifugation. The synaptosomes contain acetylcholine (ACh), synaptic vesicles, cytoplasmic markers and mitochondria. No adherent postsynaptic membranes were detected. K+ depolarization as well as the ionophore A23187 mediate Ca2+ permeation into the synaptosomes and the consequent release of ACh. Mg2+ does not evoke ACh release whereas Sr2+ and Ba2+ can replace Ca2+ in evoking K+ depolarization induced ACh secretion. In accordance with the calcium hypothesis of stimulus–secretion coupling, both K+ depolarization and the ionophore A23187 seem to mediate the release of the same population of ACh molecules. The mode of action of the ionophore X537A differs from that of A23187. X537A acts independently of Ca2+ and induces the release of a larger fraction of the ACh contained in the fractionated nerve terminals. These results demonstrate that the Torpedo synaptosomes contain the neurosecretion apparatus in a functional active state. This preparation extends the utility of synaptosomes for structural and functional biochemical studies of neurotransmission, as it uniquely contains only one neurosecretion system (cholinergic).
ANTI‐WHOLE WHITE MATTER SERUM INHIBITS INCORPORATION OF GLUCOSE AND GALACTOSE INTO THE LIPIDS OF MYELINATING SPINAL CORD CULTURES
Authors: Lehrer G. M. , Maker H. S. , Silides D. J. , Weiss C. , Bornstein M. B.
Published: October 2006

Abstract—

Myelin formation was inhibited in fetal mouse spinal cord cultures in the presence of serum from rabbits with experimental allergic encephalomyelitis produced by inoculation of whole bovine spinal cord white matter in complete Freund's adjuvant. Controls were exposed to decomplemented serum. Replacement of serum in inhibited cultures on the 18th day in vitro (DIV) with control serum (disinhibited) resulted in the appearance of visible myelin within 2–3 days. From 20 to 23 DIV, d‐[U‐14C]glucose or d‐[U‐14C]galactose was present in all media. Total protein, DNA, gangliosides and galactolipids were reduced by 21% in inhibited cultures, and activity of 2′,3′‐cyclic nucleotide 3′‐phosphohydrolase was reduced by 50%. There was little reduction in the incorporation of glucose carbon (21–23 DIV) into several lipid classes examined. Labelling of cerebrosides by galactose carbon in inhibited cultures was only 12% of that of controls while there was no reduction in the labelling of neutral lipid–cholesterol and the glycerophosphatides. Galactolipid labelling by [14C]galactose in the disinhibited cultures was intermediate between inhibited and control cultures. Differences in the effects of inhibiting medium on the incorporation of glucose and galactose carbon indicate that ceramide synthesis is less affected than is galactose incorporation to form cerebroside.
MODULATION OF THE TURNOVER RATE OF ACETYLCHOLINE IN RAT BRAIN BY INTRAVENTRICULAR INJECTIONS OF THYROTROPIN‐RELEASING HORMONE, SOMATOSTATIN, NEUROTENSIN AND ANGIOTENSIN II
Authors: Malthe‐Sorenssen D. , Wood P. L. , Cheney D. L. , Costa E.
Published: October 2006

Abstract—

The turnover rate of acetylcholine (TRACh) was measured in frontal and parietal cortex striatum, hippocampus, diencephalon and brain stem following the intraventricular injection of thyrotropin‐releasing hormone (TRH), somatostatin, neurotensin and angiotensin II. These peptides selectively change the TRACh of various brain regions suggesting specific and independent actions. This specificity of action was also tested by injecting L‐prolylglycine, poly‐L‐proline and poly‐L‐glutamate. None of these synthetic peptides affect the TRACh. TRH increases the TRACh in parietal but not in frontal cortex whereas somatostatin, neurotensin and angiotensin II failed to change the TRACh in these cortical areas. Somatostatin and neurotensin increase the TRACh in diencephalon, whereas TRH and angiotensin II do not. All four peptides decrease the acetylcholine (ACh) content of parietal cortex but not that of frontal cortex. Only somatostatin changes the TRACh in pons medulla. Larger doses of TRH, neurotensin and angiotensin II fail to elicit greater or more general changes in TRACh. In contrast, high doses of somatostatin increase the TRACh of hippocampus and induce‘barrel’rotation. Intraseptal injections of somatostatin induce a long lasting catalepsy but fail to change hippocampal TRACh or to elicit‘barrel’rotation
ADRENERGIC ENZYMES IN CULTURED MOUSE NEUROBLASTOMA: ABSENCE OF DETECTABLE AROMATIC‐l‐AMINO‐ACID DECARBOXYLASE1
Authors: Waymire Jack C. , Gilmer‐Waymire Katrina
Published: October 2006

Abstract—

The relative activities of tyrosine hydroxylase, aromatic‐l‐amino‐acid decarboxylase and dopamine beta‐hydroxylase were established in a number of clones of neuroblastoma cells isolated from the uncloned mouse C‐1300 tumor. One clone, NBD‐2, was chosen for further analysis on the basis of its relatively high activities of tyrosine hydroxylase and dopamine beta‐hydroxylase. The levels of these enzymes, and monoamine oxidase and catechol O‐methyltransferase, were at least 20‐80 fold lower in the neuroblastoma culture than in mouse superior cervical ganglion. More importantly, aromatic‐l‐amino‐acid decarboxylase activity was not even detectable in any neuroblastoma clone examined. Based on the relative sensitivities of the tyrosine hydroxylase and aromatic‐l‐amino‐acid decarboxylase assays and on the ratio of these two enzymes in the mouse ganglion, decarboxylase activity is more than 10 fold lower in the cultured cells than would be predicted on the basis of tyrosine hydroxylase activity.

Dialysis and mixing studies with neuroblastoma extracts and partially purified aromatic‐l‐amino‐acid decarboxylase did not reveal the presence of any endogenous inhibitors that could account for the low level of decarboxylase activity in the cultured cells.

During growth of the neuroblastoma cells to confluency, only one enzyme, monoamine oxidase, exhibited an elevated specific activity on the basis of cell number. However, when based on the amount of protein, the specific activity of all measurable enzymes increased in culture‐because cell protein decreased 5 fold during growth to confluency. These findings are discussed with respect to individual cell function.
BINDING OF 5‐HYDROXYTRYPTAMINE TO ACIDIC LIPIDS IN AN AQUEOUS MEDIUM
Authors: Johnson David A. , Merlone Steven C. , Loh Horace H. , Ellman George L.
Published: October 2006

Abstract—

The affinities of 5‐hydroxy‐[3H]tryptamine (5‐HT) for cerebroside sulfate, 1‐phosphatidylinositol, 1‐phosphatidylinositol 4‐phosphate, 1‐phosphatidylinositol 4,5‐bisphosphate, phosphatidic acid, and phosphatidyl serine were determined in an aqueous medium. They were observed to be, in general, much lower than and poorly correlated with the values previously reported by Johnsonet al (1977a), measured in isobutanol. This suggested that these lipids probably are not 5‐HT receptors and that drug affinities measured in organic media must be evaluated with caution.
EFFECTS OF 2‐DIMETHYLAMINOETHANOL (DEANOL) ON THE METABOLISM OF CHOLINE IN PLASMA
Authors: Ceder G. , Dahlberg L. , Schuberth J.
Published: October 2006

Abstract— The effects of chronic oral administration of 30 mM‐dimethylaminoethanol (DMAC) on the concentrations and turnover of putative acetylcholine precursors in the plasma and the CSF have been investigated. Choline (Ch) and its labelled variants were measured by gas chromatography‐mass fragmentography and lecithin, lysolecithin and sphingomyelin by spectrophotometric methods following separation by thin layer chromatography. No effects of DMAE on the phospholipids in the plasma of rabbits were found. The concentrations of Ch in the plasma of humans and rabbits and in the CSF of rabbits increased during the DMAE treatment. In the mouse labelled with deuterium Ch from the diet, DMAE increased the dilution of deuterium Ch in the plasma. Ch given by mouth to rabbits in the same dose as DMAE had no effects on plasma Ch. Intravenous infusion of 0.15 M‐Ch at a rate of 5 μM·kg−1·min−1 for 60 min increased the concentrations of Ch in the CSF as well as in the plasma. It is concluded that DMAE increases plasma Ch by enhancing the formation of endogenous Ch, perhaps through the base exchange reaction. Whether or not DMAE also increases the availability of Ch directly in the brain cannot be decided.
REGIONAL CHANGES IN CEREBRAL GABA CONCENTRATION AND CONVULSIONS PRODUCED BY d AND BY l‐ALLYLGLYCINE
Authors: Horton R. W. , Chapman Astrid G. , Meldrum B. S.
Published: October 2006

Abstract— The convulsant action of allylglycine (2‐amino‐4‐pentenoic acid) is due to the metabolic conversion of allylglycine to 2‐keto‐4‐pentenoic acid, a more potent glutamic acid decarboxylase inhibitor and more potent convulsant than the parent compound. We report regional changes in cerebral GABA concentration in rats after administration of d‐ and l‐allylglycine. d‐Allylglycine (3.75 mmol/kg) induced convulsions in 95–115 min, characterised by repeated clonic limb movements and rapid rotation around the head to tail axis. GABA concentrations were only reduced in cerebellum and ponsmedulla during the pre and post‐convulsive periods. The localised reduction of GABA concentration is consistent with the enzymic conversion of d‐allylglycine to 2‐keto‐4‐pentenoic acid catalysed by cerebral d‐amino acid oxidase, an enzyme known to be localised to the hind brain and spinal cord. l‐allylglycine (1.2mmol/kg i.p.) induced convulsions in 65 ‐90 min, characterised by violent running followed by tonic flexion and extension. During the pre‐convulsive period, GABA concentrations were reduced in all brain areas studied except the globus pallidus and ventral midbrain. The widespread decreases in GABA concentration suggest that the enzyme(s) which catalyse the conversion of l‐allylglycine to 2‐keto‐4‐pentenoic acid are widely distributed within the brain.
DETERMINATION OF ACh CONCENTRATION IN TORPEDO SYNAPTOSOMES
Authors: Morel N. , Israel M. , Manaranche R.
Published: October 2006

Abstract— The concentrations of ACh and ATP of Torpedo electric organ synaptosomes were directly measured and found to be respectively 20.0 ± 6.4 mM and 3.1 ± 0.6 mM. The synaptosomal volume was estimated by a classical space marker technique using 14C inulin and tritiated water. After counting the synaptosomes in an haemocytometer (and knowing their volume), a mean diameter of 3.5 p was calculated. The use of these classical techniques was rendered possible because of the homogeneity of the fraction and the large size of Torpedo synaptosomes.
LOCALIZATION OF 2′,3′‐CYCLIC NUCLEOTIDE‐3′‐PHOSPHOHYDROLASE OF RABBIT BRAIN BY SEDIMENTATION IN A CONTINUOUS SUCROSE GRADIENT1
Authors: Shapira R. , Mobley W. C. , Thiele S. B. , Wilhelmi M. R. , Wallace A. , Kibler R. F.
Published: October 2006

Abstract— The enzyme 2′,3′‐cyclic nucleotide‐3′‐phosphohydrolase (CNP) has been assayed in fractions from a continuous sucrose density gradient zonal centrifugation of rabbit brain homogenates. Basic protein (BP) was also assayed by a radioimmunomethod. Fractions were examined by SDS‐polyacrylamide gel electrophoresis and by electron microscopy. These studies show that the major membrane fractions in the gradient differ greatly in the content of CNP and BP, and of high molecular weight proteins (HMW). The lightest membrane fractions contained numerous multilamellae, the highest content of BP and the lowest content of CNP and HMW, while the heaviest membrane fractions contained single membrane fragments and vesicles of unknown origin, the lowest content of BP and the highest content of CNP and HMW. The fraction containing the largest amount of membrane measured by turbidity, protein content, and water‐washed dry weight contained only half the CNP specific activity of a denser fraction in the gradient. CNP specific activity in the lightest fractions was insignificant compared to that of denser fractions. Thus, we conclude that this enzyme may be absent from the typical multilamellar myelin structures but present in the single‐membrane structures associated with myelin, such as the glial membrane and the paranodal segments of myelin adjacent to the axon. BP appears to occupy the opposite positions, highest in the multilamellae and lowest in the single‐membrane structures of myelin. These studies do not exclude the possibility that CNP may not be bound to myelin membranes, but rather to a membrane of different origin. Evidence that this enzyme is a myelin‐marker enzyme is circumstantial. Our evidence indicates the enzyme could be present either in a unique portion of myelin membranes or in another membrane structure.
A COMPARISON OF MICRODISTRIBUTIONS OF TAURINE AND CYSTEINE SULPHINATE DECARBOXYLASE ACTIVITY WITH THOSE OF GABA AND l‐GLUTAMATE DECARBOXYLASE ACTIVITY IN RAT SPINAL CORD AND THALAMUS
Authors: Yoneda Y. , Kuriyama K.
Published: October 2006

Abstract— Distribution profiles of taurine and activity of cysteine sulphinate decarboxylase (CSD), the enzyme catalysing the formations of hypotaurine from cysteine sulphinate and of taurine from cysteate respectively, in the rat spinal cord and thalamus were studied in comparison with those of GABA and activity of l‐glutamate decarboxylase (GAD), the rate limiting enzyme for GABA formation. In the spinal cord (L2‐L3), it was found that taurine is fairly evenly distributed, whereas the activity of CSD is higher in the dorsal half of the spinal cord than in the ventral half. The highest CSD activity was found in the dorsal part of the dorsal horn. In the anterior part (A 5.4) of the thalamus, taurine and CSD activity were also distributed evenly and no areas having high taurine content and CSD activity were detected. In contrast with the even distributions of taurine and CSD activity, both GABA and GAD activity were distributed unevenly in the same CNS areas examined: The areas having high GABA content and GAD activity in the thalamus (A 5.4) coincided with the ventrolateral part of the ventral nucleus of thalamus (VM), entopeduncular nucleus (EP) and nucleus reuniens thalami (RE), whereas those in the spinal cord were found to be in the dorsal part of the dorsal horn and surrounding parts of the central canal, respectively. Considering a probable role of GABA in mammalian central nervous system (CNS) as an inhibitory neurotransmitter, it seems unlikely that taurine acts as an inhibitory neurotransmitter at least in the rat spinal cord and thalamus.
PHOSPHOLTPID METABOLISM IN ISOLATED NEURONAL AND GLIAL CELLS FROM BRAINS OF 17‐DAY OLD RATS1
Authors: Marggraf W. D. , Wang H. , Kanfer J. N.
Published: October 2006

Abstract—

Neuronal and glial cells were isolated from the brains of 17‐day old rats and incubated for 5 h with either radioactive inorganic phosphate, palmitate, serine, choline or ethanolamine in a tissue culture medium. A comparison of the results suggests that both neuronal and glial cells exhibit effective de novo, phospholipid synthesis and that the observed differences in the uptake are due more to quantitative rather than qualitative differences in phospholipid metabolism of both cell types. Incubations of the combined neuronal and glial fractions with 32PO4 and [3H]palmitate result in incorporations up to 100% higher than calculated from incubations of the separate fractions, suggesting that phospholipid metabolism of neuronal and glial cells may exhibit cooperativity.
CHARACTERISTICS OF GLUTAMINE vs GLUTAMATE TRANSPORT IN ISOLATED GLIA AND SYNAPTOSOMES
Authors: Weiler C. T. , Nyström B. , Hamberger A.
Published: October 2006

Abstract—

The uptake of the neurotransmitter candidates glutamate and aspartate into synaptosomes and bulk‐isolated glia was considerably more rapid than the uptake of the suspected transmitter‐precursor glutamine at low concentrations (10 μM). Glial uptake in all cases was one‐fifth to one‐third of synaptosomal, whereas isolated neurons attained very low tissue: medium ratios, probably reflecting damage to the neurons sustained during isolation. The glial and synaptosomal uptakes of glutamate both obeyed dual high‐ and low‐affinity kinetics and were negligible in the absence of external sodium, whereas glutamine was taken up in either case by an exclusively low‐affinity transport system exhibiting no sodium‐dependence. Glutamine was considerably metabolized to glutamate following transport by both glia and synaptosomes whereas glutamate remained unmetabolized
γ‐VINYL GABA: EFFECTS OF CHRONIC ADMINISTRATION ON THE METABOLISM OF GABA AND OTHER AMINO COMPOUNDS IN RAT BRAIN
Authors: Perry Thomas L. , Kish Stephen J. , Hansen Shirley
Published: October 2006

Rats were given γ‐vinyl GABA (4‐amino‐hex‐5‐enoic acid), a new irreversible inhibitor of GABA aminotransferase (GABA‐T), by daily subcutaneous injection (100mgkg) for 11 days. Amino acids were quantitated in the brains of the γ‐vinyl GABA‐treated and control animals 24 h after the last injection, and enzyme activities of GABA‐T and glutamic acid decarboxylase (GAD) were measured. Chronic administration of γ‐vinyl GABA produced a 150% increase in brain GABA content, along with marked increases in the contents of B‐alanine and homocarnosine. Brain GABA‐T activity was reduced by 26%, and GAD activity was reduced by 22%. In addition, γ‐vinyl GABA caused a marked increase in hypotaurine content in rat brain, suggesting that it acts as an inhibitor of hypotaurine dehydrogenase, and it produced significant decreases in brain contents of glutamine and threonine. Although it is an effective GABA‐T inhibitor, γ‐vinyl GABA apparently affects several other brain enzymes as well, and it may not be an ideal drug for elevating brain GABA levels in man.
CHARACTERIZATION AND TOPOGRAPHY OF THE GLYCOPROTEINS OF ADRENAL CHROMAFFIN GRANULES
Authors: Huber E. , Köunig P. , Schuler G. , Aberer W. , Plattner H. , Winkler H.
Published: October 2006

The glycoproteins of the membranes of bovine chromaffin granules were characterized by two polyacrylamide gel electrophoresis systems. Five components (I‐V) were demonstrated with apparent molecular weights ranging in the unreduced form from 45,000 to 150,000. Glycoprotein I was identified as the enzyme dopamine β‐hydroxylase. Four of these glycoproteins (with the exception of component IV) were apparently also present in the membranes of pig and horse chromaffin granules. The soluble proteins of chromaffin granules contained at least three glycoproteins. Only glycoprotein I (dopamine β‐hydroxylase) was present both in the soluble content and in the membranes of chromaffin granules. Affinity chromatography with lectins demonstrated that from the soluble proteins only dopamine β‐hydroxylase was adsorbed by concanavalin A, whereas none of these proteins reacted with wheat germ lectin and Ricinus communis agglutinin. Three membrane proteins including dopamine β‐hydroxylase and glycoprotein II as major components were adsorbed by concanavalin A, whereas wheat germ lectin bound only component II and a small amount of component III. By electron microscopy it was demonstrated that concanavalin A did not bind to intact chromaffin granules whereas ruthenium red and cationized ferritin did. Isotope labelling after galactose oxidase treatment revealed that at least the carbohydrate portion of the major glycoproteins is present on the inner side of the granule membranes facing the content.