bluuebunny/crossref_metadata_2025 huggingface dataset:
THE INFLUENCE OF PORTOCAVAL ANASTOMOSIS ON THE METABOLISM OF LABELLED OCTANOATE, BUTYRATE AND LEUCINE IN RAT BRAIN
Authors: Cremer J. E. , Teal H. M. , Heath D. F. , Cavanagh J. B.
Published: October 2006

Abstract—

Rats were given a portocaval anastomosis and 3 weeks later, when the only ultrastructural change in the CNS is watery swelling of astrocytes, several aspects of brain metabolism were studied. The uptake of leucine by the brain, its incorporation into protein and its oxidation were followed after the simultaneous injection of a mixture of L‐[114C]leucine and L‐[4,5‐3H]leucine. The concentration of leucine in blood was lowered in the operated animals whereas in brain it was increased. The specific radioactivity of leucine in the brain was comparable to values in control animals and there was no evidence of a decrease in incorporation of [1‐14C]leucine into brain proteins over the short experimental time period studied. The only difference from the controls in the oxidation of [4,5‐3H]leucine was a greater accumulation in glutamine. The amount of glutamine in the brains of the operated animals had increased 4‐fold at the time of the metabolic studies.

From dual‐labelled experiments in which a mixture containing [1‐14C]butyrate and L‐[4,5‐3H]leucine was injected intravenously, it was shown that, in both control and operated animals, the pools of brain glutamate and glutamine labelled from butyrate were metabolically distinct from those labelled from leucine. The total radioactivity appearing in brain from [1‐14C]butyrate was markedly reduced in operated animals, but the radioactivity from L‐[4,5‐3H]leucine was not.

The metabolism of [1‐14C]octanoate was compared with that of [1‐14C]butyrate. In control animals the labelling of metabolites was almost identical with either precursor. In operated animals there was no reduction in the uptake of [1‐14C]octanoate into the brain. There was evidence that the size of the glutamine pool labelled, relative to glutamate, was increased but that it had a slower fractional turnover coefficient. A link between astroglial changes and an impairment to the carrier mechanism for transport of short chain monocarboxylic acids across the blood‐brain barrier is suggested.
THE EFFECTS OF LITHIUM ON ATPase ACTIVITY IN SUBCELLULAR FRACTIONS FROM RAT BRAIN
Authors: Hesketh J. E. , Kinloch N. , Reading H. W.
Published: October 2006

Abstract— The effects of lithium chloride in vitro and in vivo were investigated on Na‐K ATPase and Mg ATPase activities in synaptic plasma membrane, mitochondrial and synaptic vesicle fractions prepared from rat brain. In vitro, lithium chloride (10−3‐10−8m) had no effect on ATPase activity in any of the fractions studied. Lithium chloride given chronically by i.p. injection (30 mg/rat/day) for 9 days had little effect on synaptic plasma membrane ATPases. Dietary administration of lithium chloride (60 mmol/kg food) produced a small but significant increase in synaptic plasma membrane Mg ATPase activity after 3 weeks administration and mitochondrial Mg ATPase activity after 1 week. There was no effect on synaptic plasma membrane Na‐K ATPase activity. Salt supplementation reduced the toxic effects of lithium administration and it is suggested that toxicity may account for some of the previously reported changes in synaptic membrane ATPases produced by lithium.
LYSINE METABOLISM IN THE RAT BRAIN: BLOOD—BRAIN BARRIER TRANSPORT, FORMATION OF PIPECOLIC ACID AND HUMAN HYPERPIPECOLATEMIA
Authors: CHANG YUNG‐FENG
Published: October 2006

Abstract—

Through the use of intravenous pulse injection of L‐[U‐14C] lysine, the blood‐brain barrier transport of L‐lysine was studied. The uptake of L‐lysine plus metabolites in the brain remained essentially unchanged at approx 0.002–0.005 nmol/g in the low dose (3μg per kg body weight) injection, and 20–40 nmol/g in the high dose (30 mg/kg) injection throughout the time intervals of up to 60 min. The uptake of L‐lysine plus metabolites in the heart, however, decreased substantially from 0.03 to 0.003 nmol/g in the low dose injection and from 320 to 62 nmol/g in the high dose injection. The plasma to heart uptake ratio only decreased slightly through the 60 min period: from 6 to 2 in either the low or high dose L‐lysine injection. The plasma to brain uptake ratio, however, decreased rapidly from a high of 62 to a low of about 4 in either the low or high dose injection throughout the 60‐min time course. Study of labeled L‐pipecolate formation in the plasma and individual organs indicates that this compound was formed only in the brain to a significant level within 0.5 min of14C‐L‐lysine intravenous pulse injection. Labeled pipecolate was recovered from heart, liver, kidney and plasma in significant quantities only at 2 min or later after pulse‐injection. It is concluded that the blood‐brain barrier of L‐lysine in the rat is not particularly strong and that the rat brain may be primarily responsible for L‐pipecolate synthesis from L‐lysine. The possible etiology of human hyperpipecolatemia is also discussed in light of the current findings.
THE PROTEIN‐MEDIATED TRANSFER OF LECITHIN TO SUB‐FRACTIONS OF MATURE AND DEVELOPING RAT MYELIN
Authors: Brammer M. J.
Published: October 2006

Abstract— Phospholipid transfer to mqelin subfractions isolated from adult. 15‐day old and 21‐day old rats has been investigated by incubating myelin with radioactively labelled sonicated lecithin Lesicles and subsequently fractionating the myelin on discontinuous sucrose density gradients. The transfer process is greatly stimulated by the addition of rat brain pH 5.1 supernatant and is dependent on the amount of supernatant present in the incubation mixture and on the incubation time. Lecithin is transferred much more rapidly to the most dense mqelin subfraction than to the less dense fractions. This difference in transfer rate is most marked in myelin isolated from adult rats. The possible relevance of these obsenations to mkelin sqnthesis and turnover is discussed.
ACETYLCHOLINESTERASE OF RAT SYMPATHETIC GANGLION: MOLECULAR FORMS, LOCALIZATION AND EFFECTS OF DENERVATION
Authors: Glsiger V. , Vlgny M. , Gautron J. , Rieger F.
Published: October 2006

Abstract— In sucrose gradient centrifugation, acetylcholinesterase (AChE, EC 3.1.1.7.) from the rat superior cervical ganglion (SCG) has been found to contain four molecular forms, characterized by their sedimentation coefficients (4 S, 6.5 S, 10 S and 16 S). Homogenization of the ganglia in various media showed that the 4 S enzyme was readily solubilized in water whereas solubilization of the 6.5 S and 10 S forms was quantitative only in media containing Triton X‐100. In order to solubilize the 16 S form, high concentrations of salt (NaCl 1 M) and detergent had to be present. AChE analysed by non‐denaturing polyacrylamide gel electrophoresis separated into five bands. Although both distribution patterns were stable, i.e. each form or band preserved its characteristic sedimentation or electrophoretic migration when reanalysed, there was no 1:1 correlation between the forms isolated by sedimentation and the bands obtained by electrophoresis: one band might contain more than one form of enzyme, and conversely one form gave rise to several bands. It was therefore impossible to derive molecular weights from electrophoretic migration in non‐denaturing gels. However, it could be shown that the results obtained by both methods of analysis were consistent.

Acetylcholinesterase from other nervous structures was analysed: in pre‐ and postganglionic nerves, the main forms were 10 S and 6.5 S, with a small proportion of 4 S; the 16 S form was not detected. In other sympathetic ganglia, the distribution of forms was identical to that of the superior cervical ganglion. In rachidian ganglia, no 16 S form could be found.

Following the section of the preganglionic nerve, the acetylcholinesterase activity of the superior cervical ganglion decreased by 50% in 3 days, and then rose again to about 80% of its original value after 2 weeks. These effects mainly reflected variations in the major 4 S and 10 S forms. The 16 S form, in contrast to its disappearance from denervated muscles, increased transiently during the first 2 weeks after denervation, reaching about twice its original activity.

A concomitant cytochemical study of normal and denervated ganglia showed that after preganglionic denervation, AChE localized in the sympathetic neurones decreased markedly and remained low even during the recovery phase. During this period a cholinesterasic activity appeared in the perineuronal glia. Controls established that the enzyme synthetized in the glia is AChE.
UTILIZATION OF POLYUNSATURATED FATTY ACID SUPPLEMENTS BY CULTURED NEUROBLASTOMA CELLS1
Authors: Robert J. , Rrebel G. , Mandel P.
Published: October 2006

Abstract— Brain phosphoglycerides are known to contain large amounts of polyunsaturated fatty acids (PUFA). However, neuroblastoma cells contain very low amounts of PUFA. Since the serum used for cell culture has been shown to be deficient in PUFA, a supplementation of this serum with various PUFA was undertaken. Linoleic, arachidonic and docosahexaenoic acids were incorporated in cell phosphoglycerides, mainly at the expense of oieic acid, while linolenic acid was only poorly incorporated. Linoleic. linolenic and arachidonic acids were transformed to their elongation and desaturation products; but the last step of transformation, which involves the action of a Δ 4 desaturase, was never observed. The levels of incorporation and transformation of exogenous PUFA could vary strikingly in different lines of neuroblastoma cells. The simultaneous addition of two PUFA (linoleic and linolenic acids) was followed by a reduction in the amount of their respective derivatives in cell phosphoglycerides. compared to that obtained when only one PUFA was given to the cells, suggesting a competitive inhibition of the desaturation of each PUFA. Such alterations in membrane lipids may provide a useful model for the study of membrane structure‐function relationships.
RELEASE OF NOREPINEPHRINE FROM NEURONS IN DISSOCIATED CELL CULTURES OF CHICK SYMPATHETIC GANGLIA VIA STIMULATION OF NICOTINIC AND MUSCARINIC ACETYLCHOLINE RECEPTORS
Authors: Greene Lloyd A. , Rein Glen
Published: October 2006

Abstract— Dissociated cell cultures of chick embryo sympathetic ganglia were incubated with [3H]nor‐epinephrine ([3H]NE) which was taken up and stored in reserpine‐sensitive sites. Exposure of the cultures to cholinergic agonists for 5 min intervals resulted in the releaseof a significant proportion (2–20%) of the intracellular stores of [3H]NE. Studies with specific cholinergic agonists and antagonists indicated that release of [3H]NE could be evoked by stimulation of either nicotinic or muscarinic receptors. Release evoked by both nicotinic and muscarinic agonists was totally blocked in the presence of 3 μM‐tetrodotoxin. thus indicating that release was mediated via active electrical responses. Release by both types of agonists was also blocked in the presence of elevated Mg2+ or when free Ca2+ was removed from the extracellular medium. These findings are consistent with the presence of a stimulus‐secretion coupling mechanism. Release evoked by nicotine was optimal in the presence of 1.2 mM‐Ca2+, whereas release evoked by the muscarinic agonist methacholine increased by about 2‐fold when the Ca2+ concentration was decreased from 1.2 to 0.3 mM. The latter observation may be due to a lowered threshold for evocation of active responses at low concentrations of Ca2+. Finally, no evidence was observed for interaction between the two types of receptors. These findings (a)indicate that cultured chick sympathetic neurons possess functional nicotinic and muscarinic cholinergic receptors as well as the ability to release NE via a stimulus‐secretion coupling mechanism; (b) suggest that such cultures may be particularly useful for studying the molecular events which link stimulation of cholinergic receptors to neurotransmitter release; and (c) provide further evidence that muscarinic receptors may play aphysiological role in ganglionic transmission.
METABOLISM OF γ‐HYDROXY‐[1‐14C] BUTYRATE BY RAT BRAIN: RELATIONSHIP TO THE KREBS CYCLE AND METABOLIC COMPARTMENTATION OF AMINO ACIDS
Authors: Doherty John D. , Roth Robert H.
Published: October 2006

Abstract— Ninhydrin decarboxylation experiments were carried out on the labelled amino acids produced following intraventricular injection of either γ‐hydroxy‐[1‐14C]butyric acid (GHB) or [1‐14C] succinate. The loss of isotope (as 14CO2) was similar for both substances. The [1‐14C]GHB metabolites lost 75% of the label and the [1‐14C] succinate metabolites lost 68%. This observation gives support to the hypothesis that the rat brain has the enzymatic capacity to metabolize [1‐14C]GHB to succinate and to amino acids that have the isotope in the carboxylic acid group adjacent to the a‐amino group. These results also indicate that the label from [1‐14C]GHB does not enter the Krebs cycle as acetate. The specific activity ratio of radiolabelled glutamine to glutamic acid was determined in order to evaluate which of the two major metabolic compartments preferentially metabolize GHB. It was found that for [1‐14C]GHB this ratio was 4.20 ± 0.18 (S.E. for n = 7) and for [l‐14C]succinate this ratio was 7.71 (average of two trials, 7.74 and 7.69). These results suggest that the compartment thought to be associated with glial cells and synaptosomal structures is largely responsible for the metabolism of GHB. Metabolism as it might relate to the neuropharmacological action of GHB is discussed.
PELIZAEUS‐MERZBACHER DISEASE: BRAIN LIPID AND FATTY ACID COMPOSITION
Authors: Bourre J. M. , Bornhofen J. H. , Araoz C. A. , Daudu O. , Baumann N. A.
Published: October 2006

Abstract— Biochemical analysis of the leukodystrophy brain from a case of Pelizaeus‐Merzbacher disease, classical type, was performed. A decrease in the amount of solid material present was found. The lyophilized brain weight was reduced to 76% of normal with a slightly greater decrease in the amount of extractable lipid. Total myelin was diminished to 7% of normal. Among specific lipids plasmalogens were present in slightly lowered amounts. Cerebrosides and sulphatides were drastically reduced to 8% of normal, whereas sphingomyelin was less severely affected. Fatty acids from phospholipids were close to normal, only enols being slightly diminished. Analysis of pure cerebrosides and sulphatides revealed that the a‐hydroxylated compounds as well as very long chain fatty acids (over C18, especially C23 to C26) were greatly reduced. For chain lengths over C18, the ratio of leukodystrophy fatty acid to normal fatty acid was close to 10%. The defect in very long chain fatty acids is estimated at 99.2% in total brain.

Thus, we have found a marked decrease in the amount of very long chain fatty acids and a less marked decrease in sphingolipids. The reduced amount of these acids appears to be partially offset by an increase in the amount of medium‐chain fatty acids in sphingolipids. We conclude that one aspect of Pelizaeus‐Merzbacher disease may be a defect in the synthesis of myelin very long chain fatty acids (as these acids are far much reduced than any other myelin molecule).
ISOLATION AND CHARACTERIZATION OF BOVINE BRAIN CATHEPSIN D
Authors: Whitaker John N. , Seyer Jerome M.
Published: October 2006

Abstract—

Bovine brain cathepsin D was purified 1774‐fold with a 19% recovery by affinity chromatography on immobilized pepstatin. Approximately 2 mg of enzyme protein were isolated from 150 g (wet weight) of bovine brain. The enzyme eluted from gel filtration as a single peak with a molecular weight of 40,000–42,000. On polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate, the predominant band migrated with a molecular weight of 48,000: however, less distinct bands were also present in the molecular weight ranges of 31,000 and 13,000. The isolated enzyme had isoelectric points over a range of pH 5–7 with 3 major peaks occurring at pH 5.6, 6.1, and 6.6. The amino acid composition of brain cathepsin D showed substantial differences from that reported for cathepsin D isolated from bovine spleen. Amino‐terminal sequence analysis revealed an Asp‐Val‐lle sequence by Edman degradation. With hemoglobin as the substrate the enzyme had an apparent K, of 60mM.
SYNAPTIC VESICLES ISOLATED FROM RAT HEART:l‐[3H]NOREPINEPHRINE UPTAKE PROPERTIES1
Authors: Bareis Donna Lynn , Slotkin Theodore A.
Published: October 2006

Abstract—

A fraction containing synaptic vesicles was isolated from rat heart by differential centrifugation, and the uptake ofl‐[3H]norepinephrine was studiedin vitro., Uptake was highly dependent upon time and temperature, and was linear for 6 min at 30° or 4 min at 37°C. About 80% of the measured uptake required both ATP and Mg2+and was inhibited by nanomolar concentrations of reserpine; no inhibition was obtained with cocaine. These properties are characteristic of storage vesicle uptake as opposed to synaptic membrane uptake. Uptake of norepinephrine was saturable and displayed a singleKmvalue of 2 μM. The uptake was completely stereospecific, as unlabeleddl‐norepinephrine was less than half as effective as unlabeledl‐norepinephrine in reducing uptake ofl‐[3H]norepinephrine. Norepinephrine uptake could be inhibited by various phenethylamines and indoleamines following the rank order: reserpine > harmaline > 5‐hydroxytryptamine > dopamine > norepinephrine. The vesicle preparation also incorporated [3H]5‐hydroxytryptamine and [3H]dopamine. 5‐Hydroxytryptamine uptake displayed aKmof 0.5 μM and a maximal uptake equivalent to that seen with norepineph‐rine; dopamine uptake followed complex kinetics. Administration of reserpinein vivoor destruction of sympathetic neurons by long‐term guanethidine treatment both eliminated the ability of the preparation to take up norepinephrine. Synaptic vesicles of cardiac sympathetic neurons thus resemble vesicles prepared from other central and peripheral catecholaminergic tissues; this method may be used readily to examine drug effects on rat heart synaptic vesicle function.
CYCLIC AMP IN THE RAT CEREBRAL CORTEX AFTER ACTIVATION OF NORADRENALINE NEURONS OF THE LOCUS COERULEUS
Authors: Korf J. , Sebens Jantiena B.
Published: October 2006

Abstract—

The levels of cyclic AMP in the rat brain were studied in vivo following destruction or stimulation of the noradrenergic pathway originating in the locus coeruleus. After chronic lesion of the locus coeruleus no alterations in cyclic AMP content were found. Electrical stimulation of the locus coeruleus produced an elevation of cyclic AMP in the cerebral cortex of chloral hydrate anaesthetized rats of 30%. Maximal increases were found after 15–60 s stimulation at a frequency of 30–100 Hz. This maximal response was slightly inhibited by phenoxybenzamine, an α‐adrenergic blocking agent, and by the β‐blocker propranolol. When the α and β blockers were administered together a highly significant decrease in cyclic AMP response was observed. Pretreatment of the rats with reserpinc +α methyl‐p‐tyrosine prevented the cyclic AMP response. In addition to the effect in the cerebral cortex, cyclic AMP‐levels were also enhanced in the hippocampus, in the striatum and in the hypothalamus. These results suggest that the locus coeruleus regulates a small fraction of cerebral cyclic AMP levels, by both α‐ and β‐adrenergic receptors.
PROTEINS OF AXONAL TRANSPORT: INTERACTION OF RAPIDLY TRANSPORTED PROTEINS WITH LECTINS
Authors: Karlsson J.‐O.
Published: October 2006

Abstract—

Rapidly transported fucose‐labelled glycoproteins from the optic system of the rabbit were solubilised with the non‐ionic detergent Berol 172.

The major labelled components were bound to wheat germ agglutinin or Concanavalin A coupled to Sepharose but not to other lectins or glycoproteins. It was concluded that rapidly transported proteins contain exposed N‐acetyl‐D‐glucosamine
HOMOCARNOSINOSIS: INCREASED CONTENT OF HOMOCARNOSINE AND DEFICIENCY OF HOMOCARNOSINASE IN BRAIN
Authors: Perry Thomas L. , Kish Stephen J. , Sjaastad Ottar , Gjessing Len R. , Nesbakken Ragnar , Schrader Harald , Lösken Aagot C.
Published: October 2006

Biochemical studies were carried out on a brain biopsy obtained from a 40 y old woman with homocarnosinosis. This patient and 2 of her siblings have a progressive neurological disorder characterized by spastic paraplegia, dementia and retinal pigmentation. Homocarnosine concentrations in their CSF, as well as in the CSF of their neurologically normal mother, are elevated 20‐40‐fold. Homocarnosine content was 4 times higher in the patient's frontal cortex than in biopsied cortex from a large group of control subjects. The activity of the synthetic enzyme, homocarnosine‐carnosine synthetase. was not increased in the homocarnosinosis patient's brain. Homocarnosinase activity, however, was undetectable in the patient's brain biopsy, while it could readily be measured in comparable biopsies from control subjects. We conclude that homocarnosinase deficiency is probably inhcrited as an autosomal recessive trait, but that it is unlikely of itself to have caused the neurological syndrome affecting our patients.
BACLOFEN: EFFECTS ON AMINO ACID RELEASE AND METABOLISM IN SLICES OF GUINEA PIG CEREBRAL CORTEX
Authors: Potashner S. J.
Published: October 2006

Slices of guinea‐pig cerebral cortex were used to investigate the effects of the antispastic drug β‐(p‐chlorophenyl)‐γ‐aminobutyrate (Baclofen, Lioresal) on the release and metabolism of several amino acids. Electrical stimulation of slices evoked (1) a relatively large release, probably from nerve terminals, of 14C‐labelled tissue glumate, aspartate and γ‐aminobutyrate (GABA) synthesized via metabolism of D‐[U‐14C]glucose and (2) a relatively small release, probably not from nerve terminals, of 14C‐labelled tissue alanine and threonine‐serine‐glutamine and of exogenous radiolabeled glutamate, aspartate, GABA and α‐aminoisobutyrate that had been taken up from the medium. Baclofen (4μM) preferentially inhibited the release of 14C‐labelled tissue glutamate and aspartate. It had no effect on the concentrations and specific radio‐activities of most of the labelled tissue amino acids in the slices. However, it increased the turnover of 14C‐labelled tissue glycine approx 4‐fold and elevated the specific radio activity of tissue alanine by 40%. It was concluded that Baclofen affects transmission not by modulating the release of the inhibitory amino acid GABA, but by selectively suppressing the release of the excitatory amino acids glutamate and aspartate from nerve terminals. Provided that this action obtains in the spinal cord, it may at least partly underlie the antispastic action of Baclofen as glutamate and aspartate are presumed to be the transmitters released from terminals of non‐nociceptive primary afferent fibers and excitatory interneurons, respectively. The Baclofen‐induced increase in glycine turnover suggests an additional effect on inhibitory glycinergic interneurons in the spinal cord.
EFFECTS OF ALTERED OSMOLALITY ON RESPIRATION AND MORPHOLOGY OF MITOCHONDRIA FROM THE DEVELOPING BRAIN
Authors: Holtzman David , Herman Mary M. , Desautel Marcia , Lewiston Norman
Published: October 2006

Abstract— The effects of altered osmolality on respiration and fine structure were studied in isolated cerebral mitochondria from mature rats (60‐100 days of age) and from rat pups in the first month of postnatal life (5, 10, 20 and 30 days). In the mature cerebral mitochondria, ADP‐dependent respiration was inhibited in media of decreased osmolality. There was a transient inhibition of ADP‐dependent respiration and a sustained increase in ADP‐independent respiration in media of increased osmolality. In contrast, cerebral mitochondria from 5‐day‐old rats showed both inhibition of ADP‐dependent respiration and increased ADP‐independent respiration in hypo‐osmolal media. In these mitochondria, inhibition of ADP‐dependent respiration was stable and ADP‐independent respiration was unchanged in media of increased osmolality. The transition to the mature respiratory response occurring with altered osmolality took place between 10 and 30 days of age. During this same age period, cerebral mitochondria showed an increasing resistance to matrix condensation in media of normal and increased osmolality.
SUBCELLULAR DISTRIBUTION OF [3H]QUINUCLIDINYL BENZYLATE BINDING ACTIVITY IN VERTEBRATE RETINA AND ITS RELATIONSHIP TO OTHER CHOLINERGIC MARKERS
Authors: Moreno‐Yanes Jose A. , Mahler Henry R.
Published: October 2006

Abstract— The subcellular distribution of binding sites for tritiated quinuclidinyl benzylate ([3H]QNB) was studied in cow retina. Primary fractions showing higher specific activity than homogenate were P2 (synaptosomal‐mitochondrial) and P3 (microsomal). P2 was subfractionated on a Ficoll gradient with the P2B subfraction exhibiting the greatest enrichment in [3H]QNB binding. Similar subfractionation of P2 on a discontinuous sucrose gradient showed that fractions of particles banding in 0.8m and in the 0.8‐1.0 m‐sucrose interface also exhibit the greatest enrichment of [3H]QNB binding. When subjected to Scatchard analysis, this reaction shows a density of sites equal to 0.212‐0.294 pmol per mg of protein. By plotting the apparent dissociation constant (KD) values vs protein concentration a‘true’KD value of 0.73 nM was obtained. Only one set of binding sites was found using three different concentrations of protein. The reaction was specificially antagonized by atropine (DI50= 7 nM) and scopolamine (DI50= 9 nM) whereas carbamylcholine and d‐tubocurarine exhibited DI50's of 0.4 and 0.15 mM, respectively. For P3 the binding of [3H]QNB is characterized by one set of binding sites with ni= 0.250 pmol per mg of protein and an apparent KD of 8.2 nM, and a DI50 for atropine of 15 nM. The [3H]QNB binding sites showed a subcellular distribution similar to that of acetylcholinesterase and choline acetyltransferase.

P1 fractions accounted for 40–60% of the total activity of the three cholinergic markers. Purification of the crude P1 yielded an additional fraction in which the cholinergic markers showed an enrichment with respect to homogenate and P1. Synaptosomes isolated from this fraction exhibited the unusual ultrastructure expected from nerve endings in the outer synaptic layer of retina.

The possible location of the muscarinic cholinergic transmitter system in the vertebrate retina is discussed.
THE SULPHATION OF VANILYLMANDELIC ACID AND HOMOVANILLIC ACID BY LIVER, SMALL INTESTINE AND BRAIN
Authors: Wong Kim Ping
Published: October 2006

Abstract— The sulpho‐conjugates of vanilylmandelic acid (VMA) and homovanillic acid (HVA) were biosynthesized in vitro from ATP and sodium sulphate and from 3′‐phosphoadenosine‐5′‐phosphosulphate (PAPS) obtained commercially or generated in vitro. Hydrolysis with sulphatase indicated the sulphate nature of these conjugates. In decreasing order of activity, the liver, small intestine and brain of various animals exhibited this sulpho‐conjugatory ability. The Km, values of VMA and HVA for the sulphotransferase of mouse liver were, respectively, 1740 and 93 μM. Competition studies suggested that the same enzyme may be involved in the sulphation of these two acids.
EFFECTS OF DEPOLARIZATION ON COFACTOR REGULATION OF GLUTAMIC ACID DECARBOXYLASE IN SUBSTANTIA NIGRA SYNAPTOSOMES
Authors: Miller Leonard P. , Walters Judith R.
Published: October 2006

Abstract— The level of saturation of glutamate decarboxylase (GAD) by cofactor, pyridoxal‐5′‐phosphate (pyridoxal‐P), determined in synaptosomes prepared from substantia nigra tissue, was reduced from 45 to 28%; when ATP was included in the homogenizing medium to prevent nonspecific activation of GAD by endogenous pyridoxal‐P. When the synaptosomes were incubated for 5–20 min at 37°C in Krebs‐Ringer phosphate buffer (KRP), the level of saturation of GAD by cofactor decreased further, from 28 to 20%. Depolarization of the nigral synaptosomes by either high K+ (55 mM) or veratridine resulted in a significant increase in the level of GAD saturation by cofactor, to 32 and 41%. respectively. Omitting Ca2+ from the incubation medium blocked the depolarization‐induced rise in the level of saturation. Depolarization with high K+ and veratridine also caused a significant decrease in the ATP concentration in the synaptosomes. No difference in ATP concentration was observed when the samples were incubated at 37°C for 5–20min or incubated in the absence of added Ca2+ with high K+. Results provide further evidence that in vivo brain GAD is largely unsaturated by cofactor and support the possibility that increased release and utilization of GABA may be associated with increases in the amount of pyridoxal‐P endogenously bound to GAD in nerve terminals.
HETEROGENEITY OF S‐100 PROTEINS OF BRAIN: SUBUNIT COMPOSITIONS
Authors: Mahadik S. P. , Korenovsky A. , Rapport M. M.
Published: October 2006

Abstract— Two populations of S‐100 proteins (III‐IVa‐1) and (III‐IVb‐1) were isolated from bovine brain by a simple three‐step procedure involving precipitation with ammonium sulfate, ion exchange chromatography and gel electrophoresis. These two fractions reacted with anti‐S‐100 serum and showed all the properties of S‐100 protein, but differed in the distribution of protein among the four subunits obtained in SDS‐gels. These subunits had apparent molecular weights of 7800, 6800, 6100, and 5200. Separations based on charge differences revealed only three subunits. Similar fractions isolated from rat brain contained only two subunits with apparent molecular weights of 7800 and 6500. The two S‐100 protein fractions also differed in the specific extinction at 280 nm and in the protein distribution among the separate bands which formed either in a 14% acrylamide‐agarose gel‐discontinuous buffer system or in 7.5% gels in the presence of calcium. The yield of S‐100 protein isolated in the presence of aids (EDTA, EGTA, mercaptoethanol, protease inhibitors) was considerably higher than in their absence (80 mg vs 60 mg/kg tissue), the predominant loss occurring in fraction III‐IVa‐1. It is concluded that 'S‐100 protein’contains a number of molecular species which have different subunit compositions and differences in stability.
ASTROGLIAL UPTAKE IS MODULATED BY EXTRACELLULAR K+
Authors: Cummins C. J. , Glover R. A. , Sellinger O. Z.
Published: October 2006

Abstract— Primary cultures of rat brain astrocytes were used to examine the uptake of the glucose analogue, 2‐deoxy‐d‐glucose (2‐DOG). 2‐DOG competes with glucose for uptake, indicating that both are transported by the same carrier system. Extracellular K+ at 11.9 mM increased the uptake of 2‐DOG at 2‐DOG concentrations greater than 100 μM. Uptake. appears Na+‐dependent only at high concentrations of 2‐DOG. This suggests that the extracellular concentrations of Na+ and K+ may regulate the astrocytic uptake of 2‐DOG.
THE CONVERSION OF [3H]TRYPTOPHAN TO 5‐[3H]HYDROXYTRYPTAMINE IN MOUSE BRAIN FOLLOWING DEPLETION OF PHENYLALANINE AND TYROSINE1
Authors: Johnson Kenneth M. , Fritz Richard R. , Vickroy Thomas W.
Published: October 2006

Abstract— Phenylalanine ammmonia‐lyase (PAL), an enzyme which converts phenylalanine (Phe) and tyrosine (Tyr) to trans‐p‐cinnamic acid and trans‐p‐coumaric acid, respectively, was administered to mice and its effect on the conversion of [3H]tryptophan to 5‐[3H]HT in the brain was measured. Although PAL significantly depleted plasma Tyr, it has little or no effect on either brain Tyr or catecholamine concentrations. Endogenous brain tryptophan levels were significantly increased 2 h after PAL administration, brain 5‐HT was dramatically increased 4 h following PAL and each returned to baseline levels by 8 h. This return to baseline was accompanied by a marked decrease in the fraction of tryptophan converted to 5‐HT during a 20 min pulse period preceding death, suggesting the activation of a compensatory decrease in 5‐HT synthesis in response to increased 5‐HT concentration. These data suggest that PAL administration readily produces reversible alterations in 5‐HT synthesis and that this may be a fruitful approach to studying brain 5‐HT function.
Rat Brain Protein Synthesis Declines During Postdevelopmental Aging
Authors: Dwyer Barney E. , Fando Juan L. , Wasterlain Claude G.
Published: October 2006

: Using improved methods to measure brain protein synthesis in vivo (Dunlop et al., 1975) we have established that brain protein synthesis significantly declines in forebrain, cerebellum and brain stem when mature rats (3 months old) are compared to old rats (22.5 months old). The incorporation of (3H) L‐lysine into forebrain protein is reduced 11% in 10.5 month old rats compared to 3 month old rats. A further reduction of 9% occurred between 16.5 months and 22.5 months. Our data suggest that reduced levels of protein synthesis initiation may be responsible, at least in part, for this age‐related decline.
Effect of 6‐Hydroxydopamine Lesions of the Medial Prefrontal Cortex on Neurotransmitter Systems in Subcortical Sites in the Rat
Authors: Pycock C. J. , Carter C. J. , Kerwin R. W.
Published: October 2006

Abstract: The effect of lesions of the catecholamine nerve terminals in the medial prefrontal cortex of the rat on neurotransmitter mechanisms within the basal ganglia has been investigated. Bilateral 6‐hydroxydopamine lesions were stereotaxically placed in the dopamine‐rich (DA) area of the frontal cortex. Animals were pretreated with desmethylimipramine to block the uptake of neurotoxin into noradrenergic (NA) terminals and to make it more selective for DA terminals. The lesion produced a selective reduction of both NA and DA from the medial prefrontal cortex, a result related to falls in tyrosine hydroxylase activity at this site. Lesioned animals showed enhanced DA turnover and utilisation in striatal and limbic regions. There was no change in subcortical tyrosine hydroxylase activity. In addition there were significant falls in other putative neurotransmitters within basal ganglia sites, including 5‐hydroxytryptamine and GABA. Decreased activity of the neurotransmitter‐synthesizing enzymes glutamate decarboxylase and choline acetyltransferase was also recorded in certain regions of the basal ganglia. The results suggest that frontal cortical catecholamine systems may serve to regulate various neurotransmitter mechanisms in the basal ganglia.
The Extrusion of Sodium Ions from Presynaptic Nerve Endings of Rat Cerebral Cortex
Authors: Logan J. G.
Published: October 2006

(Na+‐K+) ATPase is present in synaptosomal preparations and it is assumed to represent the sodium‐potassium pump. 10 μm‐noradrenaline activates (Na+‐K+) ATPase approximately 100%, but 50 μm‐noradrenaline does not stimulate the rate of 22Na extrusion from synaptosomes. The results suggest that it is unlikely that the noradrenaline stimulation of (Na+‐K+) ATPase is part of a feedback mechanism whereby released noradrenaline can influence the activity of the presynaptic sodium pump.
Protease Inhibitors Reduce Effects of Denervation on Muscle End‐Plate Acetylcholinesterase
Authors: Fernandez Hugo L. , Duell Myron J.
Published: October 2006

Abstract: The effects of certain protease inhibitors on end‐plate acetyl‐cholinesterase (AChE) activity, as well as on wet weight and total protein, were studied in vivo in intact and denervated anterior gracilis muscles from the rat. A combination of leupeptin, pepstatin, and aprotinin, administered intraarterially, partly prevented the early (24 h) denervation‐induced decrease in muscle weight and protein content. In turn, leupeptin and aprotinin, either alone or in combination, markedly reduced the decay of AChE activity in the denervated muscles, whereas pepstatin alone was ineffective. Such effects were additive in that the inhibitors in combination were more effective than when they were used separately. Additional experiments indicated that none of the inhibitors, at the concentrations used, affected AChE activity directly, nor did they have a significant effect during processing of the muscle samples. These findings indicate that the initial decay of AChE activity with denervation was effectively reduced by the inhibitors, probably through inactivation of proteolytic enzymes which, otherwise, would be increased in denervated muscle.
Thiamine and Cholinergic Transmission in the Electric Organ of Torpedo
Authors: Eder Lorenza , Dunant Yves
Published: October 2006

Abstract: The electric organ of Torpedo marmorata was found to contain as much as 120 ± 24 nmol of thiamine per g of fresh tissue. The vitamin was distributed as nonesterified thiamine (32%), thiamine monophosphate (22%), thiamine diphosphate (8%), and an important proportion of thiamine triphosphate (38%). A high level of thiamine triphosphate was found in synaptosomes isolated from the electric organ. In contrast, the synaptic vesicles did not show any enrichment in thiamine, whereas they contained a marked peak of acetylcholine (ACh) and ATP. Thus thiamine seems to be very abundant in cholinergic nerve terminals; its localization is apparently extravesicular, either in the axoplasm or in association with plasma membrane. When calcium was reduced and magnesium increased in the external medium, the efficiency of transmission was diminished, owing to inhibition of ACh release; in a parallel manner the degree of thiamine phosphorylation was found to increase—this condition is known to modify the repartition of ACh between vesicular and extravesicular compartments. Electrical stimulation, which causes periodic variations of the level of ACh and ATP, also caused significant changes in thiamine esters. In addition, related changes of the vitamin and the transmitter were observed under other conditions, suggesting a functional link between the metabolism of thiamine and that of ACh in cholinergic nerve terminals.
Catecholamine‐Sensitive Guanylate Cyclase from Human Caudate Nucleus
Authors: Frey William H. , Senogles Susan E. , Heston Leonard L. , Tuason Vicente B. , Nicol Susan E.
Published: October 2006

Abstract: Partial purification of soluble guanylate cyclase on DEAE‐Sephacel yields two separate peaks of guanylate cyclase activity. After 10‐fold purification of the soluble enzyme, guanylate cyclase is markedly inhibited by micromolar concentrations of dopamine (I50= 0.2 μm). Dopamine inhibition is observed whether the reaction is conducted with Mn21 or with Mg2+, under atmosphere or N2(g), and using enzyme from either peak from the DEAESephacel column. Other catecholamines also inhibit partially purified guanylate cyclase with an order of potency at 1 μm of: dopamine =l‐DOPA > norepinephrine = isoproterenol = adrenochrome > epinephrine. The structural requirements for inhibition are two free hydroxyl groups on the phenyl ring and an ethylamine side chain. Dopamine also inhibits the Triton X‐100‐solubilized microsomal guanylate cyclase after partial purification on DEAESephacel. Neither chlorpromazine, propranolol, nor phentolamine at 20 μm effectively block the dopamine inhibition of partially purified soluble guanylate cyclase. Micromolar concentrations of the reducing agents dithiothreitol and glutathione also inhibit partially purified guanylate cyclase, but unlike these agents, catecholamines can inhibit whether added in the reduced or the oxidized forms. Inhibition of enzyme activity by micromolar concentrations of dopamine, adrenochrome, or dithiothreitol is rapidly reversed by dilution and the dopamine inhibition is competitive with MgGTP. Inhibition does not appear to involve covalent binding or to result from the ability of catecholamines to reduce the concentrations of oxygen or free radicals in solution.
Time Course and Localization of the Effects of Estrogen on Glutamic Acid Decarboxylase Activity1
Authors: McGinnis Marilyn Y. , Gordon John H. , Gorski Roger A.
Published: October 2006

Abstract: Two approaches were used in an attempt to characterize the effect of estrogen on glutamic acid decarboxylase (GAD) [EC 4.1.1.15] activity in ovariectomized rats. In the first experiment, estradiol‐17β (E2) was unilaterally implanted in one of five different brain areas. After 3 days of estrogen exposure, the animals were sacrificed, and GAD activity in the substantia nigra (SN) and ventral tegmental region (VTR) was measured. Estrogen implanted into the preoptic area and the ventromedial nucleus was ineffective, as were implants of cholesterol, regardless of implant site. However, GAD activity was decreased in the SN when E2 was implanted into the caudate nucleus or amygdala and in the VTR when implanted into the nucleus accumbens septi. Furthermore, this decrease in GAD activity occurred only in the implanted side. In the second experiment, the time course of changes in GAD activity was measured in ovariectomized rats given a single systemic injection of either 8μg estradiol benzoate (EB) or oil. Rats were sacrificed at 0, 12, 29, or 53 h postinjection. It was found that GAD activity in the SN was maximally suppressed 29 h after EB, whereas decreased GAD activity in the VTR was apparent 12 h after EB but had returned to normal by 29 h. Oil injections had no significant effect on GAD activity. These results suggest that there may be two separate and distinct γ‐aminobutyric acid pathways, which are differentially responsive to estrogen.
Evidence Against Dopaminergic and Further Support For α‐Adrenergic Receptor Involvement in the Pineal Pho sphatidy lino sitol Effect
Authors: Nijjar Mohinder S. , Smith Thomas L. , Hauser George
Published: October 2006

Abstract: Several α‐adrenergic receptor agonists and antagonists were used to strengthen the earlier findings that the stimulation by (‐)‐norepinephrine of 32P1 incorporation into acidic phospholipids, especially phosphatidylinositol, in the rat pineal gland is mediated through α‐adrenergic receptors. Dopamine was able to induce similar stimulation, although always to a smaller extent than equimolar concentrations of norepinephrine. The dopaminergic agonists apomorphine and piribedil did not increase phosphatidylinositol labeling. A number of antagonists considered to act primarily at dopaminergic or α‐adrenergic receptors respectively completely prevented dopamine from exerting its effect. Both types of antagonists also were able to inhibit in varying degree the elevation of phospholipid labeling induced by norepinephrine. Dopamine increased phosphatidylinositol turnover without first being converted to norepinephrine, inasmuch as dopamine β‐hydroxylase inhibitors had no influence on dopamine activity. Dopamine and α‐agonists competitively activated the receptors involved in the phospholipid effect. The conclusion drawn from the several lines of evidence is that only α‐adrenergic receptors are concerned with the changes in pineal phospholipid metabolism brought about by the various agonists used and that the action of dopamine occurs through these receptors rather than through discrete dopaminergic receptors.
Studies on Polyadenylic Acid‐Containing RNA from Developing Nervous System of the Chicken the
Authors: Murphy Colleen A. , Hu Yu‐Wan , Mezei Catherine
Published: October 2006

Abstract: To investigate certain biochemical aspects of myelination, a study was undertaken of the messenger‐like RNA in the nervous system of pre‐ myelinating 14‐day embryos and of myelinating 17‐day embryos and 3‐day chicks. The central and peripheral nervous systems of the chick were found to contain and to actively synthesize poly(A)+ RNA. RNA species binding to oligo(dT)‐cellulose contained a relatively high proportion of adenylate residues and were resistant to the actions of pancreatic and T1 ribonucleases. Preparations labeled by incubation with adenosine in vitro showed a decrease in the proportion of poly(A)+ RNA as the age of the animal increased, while preparations labeled in vivo exhibited the opposite trend. Polyacrylamide gel electrophoretograms of both in vivo and in vitro labeled pqeparations showed that the poly(A)+ fractions contained mainly heterodisperse RNA species. The average molecular size of poly(A)+ RNAs of purified polysomal fractions of nerve RNA from 3‐day chicks was smaller than 18S, whereas that of total poly(A)− RNA was larger than 18s. The proportion of poly(A)+ molecules larger than 18s was lower in the rapidly myelinating nerve tissues of 17‐day embryos and post‐hatching chicks than in those of premyelinating 14‐day embryos. Similar results were obtained for crude nuclear RNA fractions or RNA preparations fractionated under denaturing conditions. These results are consistent with previous work showing that the embryonic peripheral nerve contains a larger proportion of high‐molecular‐weight, messenger‐like RNA molecules than does nerve tissue from young chicks or adults.
Enhancement of Tryptophan Uptake by Divalent Cations in the Absence of Sodium Ions
Authors: Bruinvels J. , Moleman P.
Published: October 2006

Abstract: Nations were found to inhibit the uptake of L‐tryptophan into synaptosomes with a shallow dose‐response curve. Almost maximal inhibition was obtained with 10 mM‐Na+. The divalent cations Ca2+ and Mg2+ were shown to be responsible for the increased uptake of L‐tryptophan in the absence of Na+ ions. Other divalent cations also promoted tryptophan uptake under this condition (Ca2+ < Mg2+ < Mn2+ < Fe2+ < Zn2+ < Cu2+). It was concluded that monovalent chelate complexes were responsible for this enhancing effect. The measured L‐tryptophan uptake was the net product of membrane bound and unbound tryptophan. Both bound and unbound tryptophan were increased in the presence of divalent cations. If no divalent cations were added to the incubation medium, Na+ ions decreased the unbound tryptophan but were without effect on bound tryptophan. Under these circumstances D‐tryptophan had no effect on binding of the L‐isomer and affected the transport of 1.‐tryptophan only at very high does (100 x conc. L‐tryptophan). These results suggest that I ‐tryptophan binds to a stereospecific transport carrier located in the synaptosomal membrane and that Na+ ions prevent the translocation of this carrier amino acid complex from the outer to the inner site of the neuronal membrane.
Differential Transmitter Release from Nerve Terminals Isolated from Basal Ganglia and Substantia Nigra
Authors: Hardy J. A. , de Belleroche J. S. , Border D. , Bradford H. F.
Published: October 2006

Abstract: The K+‐induced release of amino acids and dopamine from synaptosomes of basal ganglia and substantia nigra of sheep was studied. K+ (56 mM) caused an increase in the release of GABA from caudate, putamen, globus pallidus, and substantia nigra, the increased release being 227, 171, 198, and 366%, respectively, compared with samples incubated without stimulation. The release of glutamate was also increased by 56 mM‐K+ (136–183%) from all regions except the globus pallidus, and a significant release of aspartate was only seen in response to K+ stimulation of synaptosomes from putamen (50%). Veratrine (75 μM) also stimulated a similar pattern of amino acid release from these regions. Regional correlation was shown between the presence of an uptake system for an amino acid and its evoked release. [14C]Dopamine formed from L‐[U‐14C]tyrosine was released only from caudate and putamen synaptosomes by K+ stimulation, the increases being 105% and 74%, respectively. Synthesis of [14C]dopamine from L‐[U‐14C]tyrosine occurred only in synaptosomes prepared from these two regions and was not detected in synaptosomes from substantia nigra or globus pallidus although whole‐tissue homogenates of substantia nigra were able to synthesise dopamine.
m‐Synephrine: Normal Occurrence in Adrenal Gland
Authors: Midgley John M. , Couch Margaret W. , Crowley Jan R. , Williams Clyde M.
Published: October 2006

Abstract: Gas chromatography‐mass spectrometry‐selected ion monitoring has been used to identify m‐synephrine (phenylephrine) in bovine adrenal gland. After ion exchange chromatography, m‐synephrine was converted to its N‐trifluoroacetyl‐O‐trifluoroacetoxy derivative and identified by retention time and relative intensities of the two characteristic ions at m/e 140 and m/e 455. Deuterated m‐synephrine was synthesized and used as an internal standard for quantitative analysis. Bovine adrenal gland contains 83 ng g‐1 (range, 33‐131) of endogenous m‐synephrine.