bluuebunny/crossref_metadata_2025 huggingface dataset:
Peroxidative Changes in Brain Cortical Fatty Acids and Phospholipids, as Characterized During Fe2+‐ and Ascorbic Acid‐Stimulated Lipid Peroxidation In Vitro
Authors: Rehncrona Stig , Smith David S. , Åkesson Björn , Westerberg Eva , Siesjö Bo K.
Published: October 2006

Abstract: The occurrence of peroxidative damage, as distinguished from anaerobic damage, to brain fatty acids and phospholipids was characterized in vitro. Fe2+ and ascorbic acid were used to stimulate peroxidation in cortical homogenates from rat brain incubated with or without oxygen. Lipid peroxidation was established in samples incubated with oxygen by increased diene conjugation, accumulation of thiobarbituric acid‐reactive material (TBAR) and of lipid‐soluble fluorescent products. No peroxidation occurred in samples incubated in the absence of oxygen (100% N2). Lipid peroxidation was characterized by a selective loss of arachidonic acid and docosahexaenoic acid and by degradation of ethanolamine phosphoglyceride, while choline phosphoglyceride did not change. During the course of peroxidation there were parallel increases in products of lipid peroxidation concomitant with the decrease in polyenoic fatty acids. The maximal changes in diene conjugation and TBAR occurred earlier than the maximal changes in fluorescent material and fatty acids. It is concluded that measurements of changes in brain fatty acid and phospholipid composition may be a useful tool to establishment of whether peroxidative damage is important in vivo in situations with a critically reduced oxygen supply. Estimation of lipid‐soluble fluorescence in vivo may also be useful, since it is considered to reflect the accumulation of stable end products of peroxidation.
Free Fatty Acids in the Rat Brain in Moderate and Severe Hypoxia
Authors: Gardiner Mark , Nilsson Bengt , Rehncrona Stig , Siesjö Bo K
Published: October 2006

Abstract: The effects of mild, moderate, and severe hypoxia on cerebral cortical concentrations of free fatty acids (FFAs) were investigated in artificially ventilated rats under nitrous oxide anaesthesia. No change occurred during either mild (arterial Po2 35–40 mm Hg) or moderate (Po2 25–30 mm Hg) hypoxia. The effects of severe hypoxia (Po2 about 20 mm Hg) combined with hypotension (mean arterial blood pressure 80–85 mm Hg) varied with the EEG pattern and the tissue energy state. Thus, a major increase in total as well as in individual FFAs occurred first when EEG was severely depressed (almost isoelectric) and energy homeostasis disrupted. On a relative basis the greatest change occurred in free arachidonic acid. It is concluded that hypoxia is associated with an increase in the concentrations of FFAs in brain tissue, provided that tissue oxygen deficiency is severe enough to cause tissue energy failure. However, an increase in FFAs does not invariably accompany minor reductions in the adenylate energy charge (EC) of the tissue.
Glutamic Acid Decarboxylase in Sea Lamprey (Petromyzon marinus): Characterization, Localization, and Developmental Changes
Authors: Wald Uri , Selzer Michael E. , Krieger Neil R.
Published: October 2006

Abstract: We have carried out assays for glutamic acid decarboxylase (GAD) in homogenates of brain and spinal cord from larval and adult sea lamprey (Petromyzon marinus). The enzyme had similar characteristics in both stages. Optimal pH was 6.8; optimal temperature was 27–30° C; Km at 27°C was 5 mM. GAD activity was distributed uniformly along the length of the spinal cord. Specific activities for the larval cord and brain were 26 and 63 nm CO2/mg protein/h. respectively. The specific activities for the adult cord and brain were 29 and 236 nm CO2/mg protein/h, respectively. Thus, the activity of cord homogenates did not change significantly between larval and adult stages, but that of the brain increased about fourfold.
Effect of Increasing Choline, In Vivo and In Vitro, on the Synthesis of Acetylcholine in a Sympathetic Ganglion
Authors: O'Regan S. , Collier B.
Published: October 2006

Abstract: The experiments described in this paper were designed to test whether increasing choline availability over normal physiological levels increases acetylcholine synthesis in the cat's superior cervical ganglion. When ganglia were perfused with Krebs solution, an increase in the medium's choline concentration over physiological (10−3M) levels increased tissue choline but did not increase tissue acetylcholine or the release of acetylcholine from stimulated ganglia. However, increasing plasma choline in the whole animal increased ganglionic acetylcholine levels. The basis for this difference in the effects of in vivo and in Vitro exposure to elevated choline levels on the tissue acetylcholine content was found to involve plasma factor(s), rather than indirect actions of choline, and the acetylcholine content of isolated ganglia was increased when the tissue was perfused with plasma, instead of Krebs solution, containing 10−3M‐choline. The extra acetylcholine generated by this procedure was associated with a subsequent transient increase in transmitter release during short intervals of stimulation, but most of the extra acetylcholine was not readily available for release from stimulated ganglia. It is concluded that increasing choline available to sympathetic ganglia over physiological concentration does not have a sustained effect on the turnover of releasable transmitter under the conditions of these experiments.
Properties of Bovine Oligodendroglia Isolated by a New Procedure Using Physiologic Conditions
Authors: Farooq Muhammad , Cammer Wendy , Snyder D. Stephen , Raine Cedric S. , Norton William T.
Published: October 2006

Abstract: A new class of procedures, previously shown to permit the isolation of pure oligodendroglia from whole rat cerebrum, has been applied with equal or greater success for the bulk isolation of this cell type from bovine white matter. Thus, the generality of this approach has been demonstrated. The bovine preparations have a purity of >90% intact, phase‐bright oligodendroglia and are obtained in a yield of 8 × 106 cells per gram of white matter. Within 1 day it is possible to obtain a preparation containing 60 mg of protein from a single cell type. These cells show a higher degree of ultrastructural preservation of all cytoplasmic constituents than previously obtained. The values for protein (33 pg/cell), DNA (5.4 pg/cell), and lipid (5–6 pg/cell) are very similar to those obtained with an earlier procedure. The cell lipids are rich in galactolipid, which comprises 20% of the total. The activity of the “myelin‐specific” enzyme, 2′,3′‐cyclic nucleotide 3′‐phosphohydrolase (EC 3.1.4.37), is 4.7 μmol/min/mg protein, similar to that obtained previously for isolated oligodendroglia and about 25–40% of that found in myelin. The activity of 5′‐nucleotidase (EC 3.1.3.5) in the cells is about 10% of that in myelin or white matter.
A Sensitive Radiometric Assay for Ornithine Aminotransferase: Regional and Subcellular Distributions in Rat Brain
Authors: Wong P. T.‐H. , McGeer E. G. , McGeer P. L.
Published: October 2006

Abstract: A radiometric assay for ornithine aminotransferase was developed using [1‐14C]α‐ketoglutarate as the labeled substrate and glutamate decarboxylation as a linking step. This assay gives near total measurement of ornithine aminotransferase activities that are, respectively, about 1.5 and 10 times larger than those obtained by the spectrophotometric assay and the radiometric assay using [1‐14C]ornithine. It is also the most sensitive of the three assay procedures.

Consistent with previous reports, brain ornithine aminotransferase was found to be present predominantly in synaptosomes. Regional distribution of the enzyme correlated with that of the high‐affinity uptake of glutamate, but not with the distribution of glutamate decarboxylase. Ornithine aminotransferase may be responsible for the synthesis of glutamate in glutamatergic neurons but it is clearly not localized exclusively in such neurons.
A Bioluminescence Method for the Demonstration of Regional Glucose Distribution in Brain Slices
Authors: Paschen W. , Niebuhr I. , Hossmann K.‐A.
Published: October 2006

Abstract: Regional glucose distribution in brain slices was assessed by a bioluminescence technique. The reaction is based on light emission of luminiferous marine bacteria, Vibrio fischeri, induced by NADPH. Freeze‐dried brain slices were covered by a solution which contained: (a) enzymes and substrates for glucose oxidation and NADPH formation and (b) an extract of Vibrio fischeri for the bioluminescence reaction. Glucose‐induced bioluminescence was recorded on photographic film. Patterns of regional decrease in glucose concentration were demonstrated in cat brains after occlusion of the left middle cerebral artery. This decrease correlated well with a concomitant depletion of ATP and an increase in NADH‐fluorescence.
Coupling of Dopamine Oxidation (Monoamine Oxidase Activity) to Glutathione Oxidation Via the Generation of Hydrogen Peroxide in Rat Brain Homogenates
Authors: Maker Howard S. , Weiss Cipora , Silides Demetra J. , Cohen Gerald
Published: October 2006

Abstract: Homogenates of perfused rat brain generated oxidized glutathione from reduced glutathione during incubation with dopamine or serotonin. This activity was blocked by pargyline. a monoamine oxidase inhibitor, or by catalase, a scavenger of hydrogen peroxide. These results demonstrate formation of hydrogen peroxide by monoamine oxidase and the coupling of the peroxide to glutathione peroxidase activity. Oxidized glutathione was measured fluorometrically via the oxidation of NADPH by glutathione reductase. In the absence of added dopamine or serotonin, a much smaller amount of reduced glutathione was oxidized: this activity was blocked by catalase, but not by pargyline. Therefore, endogenous production of hydrogen peroxide, not linked to monoamine oxidase activity, was present. These results indicate that glutathione peroxidase (linked to hexose monophosphate shunt activity) can function to eliminate hydrogen peroxide generated by monoamine oxidase and other endogenous sources in aminergic neurons.
The Rapid Uptake and Release of [3H]Adenosine by Rat Cerebral Cortical Synaptosomes
Authors: Bender A. S. , Wu P. H. , Phillis J. W.
Published: October 2006

Abstract: Adenosine, a putative inhibitory transmitter or modulator in the brain, is rapidly transported by rat cerebral cortical synaptosomes. The uptake may represent a facilitated diffusion process, which is saturable and temperature‐dependent. In this study, the uptake process was very rapid, reaching completion within 60 s of incubation at 37°C, and had an apparent Km value of 0.9μM and a Vmax value of 5.26 pmol/mg protein/ 30 s. Over 70% of the adenosine taken up remained unchanged, whereas 14% was metabolized to inosine. Twelve percent of the adenosine was converted to nucleotides. Rapid uptake of adenosine into rat cerebral cortical synaptosomes was partially inhibited by replacing Na+ with choline chloride in the medium. Ca2+ ion is important for the uptake process, as inhibition of adenosine uptake occurs in the presence of either Co2‐ or EGTA. Rapid uptake of adenosine is apparently mediated by a nucleoside carrier, a conclusion based on its inhibition by a variety of purine and pyrimidine nucleosides. Uptake was inhibited by dipyridamole, hexobendine, papaverine, flurazepam, and morphine. Over 60% of the adenosine taken up by the rapid uptake system (30 s) was released by depolarizing agents. In contrast, only 30% of the adenosine taken up during a 15‐min incubation period was released under the same conditions. [3H]Adenosine was the predominant purine released in the presence or absence of depolarizing agents. The basal and KCl‐evoked release mechanisms were found to be at least partially Ca2+‐dependent, however, the release of adenosine by veratridine was increased in the presence of EGTA. This finding is in agreement with the reported Ca2+‐independent release of ATP from brain synaptosomes. The present findings suggest that there are at least two functional pools of adenosine in synaptosomes. Adenosine taken up by different uptake systems may be destined for different uses (metabolism or release) in the neuron.
Immunochemical Characterization of Antisera to Rat Neurofilament Subunits
Authors: Autilio‐Gambetti Lucila , Velasco Manuel E. , Sipple Jack , Gambetti Pierluigi
Published: October 2006

Abstract: Antisera raised to the 68,000, 145,000 and 200,000 molecular weight subunits of rat neurofilaments were used for immunochemical staining of polypeptides separated by one‐ and two‐dimensional gel electrophoresis. It was found that each antiserum reacts intensely with its corresponding neurofilament subunit and weakly with the other two subunits. All the antisera also react with a polypeptide of molecular weight 57,000 present in neurofilament‐rich preparations from both rat spinal cord and peripheral nerve. This polypeptide is different from either tubulin or vimentin and may represent a neurofilament breakdown product, since it varied in amount from preparation to preparation. The three antisera also reacted with the polypeptide subunits of chicken and goldfish neurofilament despite the considerable difference in molecular weight between these subunits and those of mammalian neurofilament. Key Words: Neurofilaments–Antibodies–Immunochemical. Autilio‐Gambetti L. et al. Immunochemical characterization of antisera to rat neurofilament subunits. J. Neurochem. 37, 1260‐1265(1981).
L‐Proline Inhibition of Glutamate Release
Authors: Keller Elizabeth , Davis Joel L. , Tachiki Kenneth H. , Cummins Joseph T. , Baxter Claude F.
Published: October 2006

Abstract: The influence of 1 mm‐l‐proline on electrically stimulated release of endogenous glutamate from slices of rat frontal cortex was measured. One mm‐l‐proline approximates the in vitro concentration that inhibits glutamate‐induced spreading depression. Also, this l‐proline level has been reported to be present in brain after an intraperitoneal injection that induced amnesia in chicks. l‐Proline but not d‐proline exhibits an inhibitory effect on glutamate release, thus supporting the suggestion that this mechanism may play a role in memory retention and/or formation.
Anesthetics Affect the Cerebral Metabolic Response to Circulatory Catecholamines
Authors: Artru Alan A. , Nugent Michael , Michenfelder John D.
Published: October 2006

Abstract: This study examined whether the effect of intravenous infusions of either epinephrine or norepinephrine on cerebral metabolic rate for oxygen (CMRo2) in the dog was modified by different anesthetics. Infusions of either epinephrine or norepinephrine at rates of 0.1‐0.25 μ kg−1min−1 reversibly increased the CMRo2 by 17–23% during anesthesia with cyclopropane 20% and nitrous oxide 50% in oxygen, whereas infusions at rates of 0.1‐25.0 μg‐kg−1‐min−1 had no effect in dogs anesthetized with other inhalational or intravenous agents. Cyclopropane/nitrous oxide also increased permeability of the blood‐brain barrier to Evan's blue dye whereas the other anesthetics tested did not. It is concluded that epinephrine and norepinephrine crossed the blood‐brain barrier during cyclopropane anesthesia, accounting for the increase in CMRo2. The authors speculate that cyclopropane may have increased blood‐brain barrier permeability by a direct effect on endothelial cells or by affecting central adrenergic systems and that epinephrine or norepinephrine may increase CMRo2 either by a direct action on neuronal receptors or via metabolically coupled synaptic events.
The Phosphorylation of Proteins in Hippocampal Slices: Effects of Noradrenaline and of Pretreatment with Kainic Acid
Authors: Hofstein Raphael , Segal Menachem
Published: October 2006

Abstract: Hippocampal slices were incubated in the presence of [32P]Pi, and protein phosphorylation was examined by means of sodium dodecyl sulfate‐gel electrophoresis. Incubation for at least 30 min with 300 μCi of [32P)Pi/brain slice gave rise to the phosphorylation of 8–10 protein bands. Most of these bands showed enhanced phosphorylation in response to noradrenaline. The basal phosphorylation of kainic acid‐pretreated hippocampal slices was enhanced two‐ to threefold compared with controls. There was also an additional increase in kainic acid‐pretreated slices in the response to noradrenaline. 8‐Br‐Cyclic AMP and phosphodiesterase inhibitors, such as papaverine or isobutylmethyl‐xanthine, had no effect on the phosphorylation patterns.
Studies on Cerebellar Haem Metabolism in the Rat In Vivo
Authors: De Matters Francesco , Ray David E.
Published: October 2006

Abstract: Rats were injected intraventricularly with 5‐amino[4‐14C]laevulinate and the radioactivity recovered in the total cerebellum homogenate and in its haem and porphyrin fractions was determined in time. Two phases could be distinguished in the decline of haem radioactivity, suggesting labelling of at least two pools of widely different turnover rates. Succinyl acetone, when injected intraventricularly, caused a marked and long‐lasting inhibition of cerebellar 5‐aminolaevulinate dehydratase activity and a corresponding inhibition of the incorporation of [14C]5‐aminolaevulinate into cerebellar haem in vivo. Inhibition of cerebellar haem biosynthesis by succinylacetone was followed by stimulation of the first enzyme of the pathway, 5‐aminolaevulinate synthase, whereas intraventricular injection of haematin led to a significant depression of the activity of the enzyme. This suggested that the cerebellar 5‐aminolaevulinate synthetase is regulated by haem through a negative feedback mechanism. Rats given repeated doses of succinylacetone, so as to maintain 80% inhibition of their cerebellar 5‐aminolaevulinate dehydratase activity for 5 days, failed to exhibit any obvious symptoms of toxicity but became more sensitive to the neurotoxic effects of large intraventricular doses of 5‐aminolaevulinate.
Vimentin and 70K Neurofilament Protein Co‐exist in Embryonic Neurones from Spinal Ganglia
Authors: Jacobs Michael , Choo Qui Lim , Thomas Clive
Published: October 2006

Abstract: The mesenchymal intermediate filament protein vimentin and the 70K component of neurofilament were detected by two‐dimensional gel electrophoresis in cultures of pure sensory and sympathetic neurones derived from chick embryos. The identities of these neuronal intermediate filament proteins were confirmed by comparison of their molecular weights, isoelectric points, and peptide patterns from limited papain digestions with those of the corresponding proteins from fibroblasts and brain, respectively. A specific antibody to vimentin stained filamenteous structures and colcemid‐induced coils in both neurones and associated satellite cells. In contrast, a specific antibody to the 70K neurofilament protein stained these structures solely in neurones. This neurone‐specific staining, as well as its molecular weight and isoelectric point, distinguishes the 70K neurofilament protein from the 68K neurofilament as sociated protein described by others, which has been claimed to resemble the tubulin assembly protein.
Subcellular Distribution of Prolyl Endopeptidase and Cation‐Sensitive Neutral Endopeptidase in Rabbit Brain
Authors: Dresdner Karl , Barker Louis A. , Orlowski Marian , Wilk Sherwin
Published: October 2006

Abstract: The subcellular distribution of prolyl endopeptidase, and of cationsensitive neutral endopeptidase, two enzymes actively metabolizing many neuropeptides, was determined in homogenates of rabbit brain. The subcellular distribution of both enzymes was more similar to lactate dehydrogenase, a cytoplasmic enzyme marker, than to choline acetyltransferase, a synaptosomal marker. Only 35% of the activity of these two neutral endopeptidases was found in the crude mitochondrial fraction (P2), the bulk of the remaining activity being associated with the high‐speed supernatant. Prolyl endopeptidase and cation‐sensitive neutral endopeptidase thus can be regarded as mainly cytoplasmic enzymes in the rabbit brain.
Characterization, Regional Distribution, and Subcellular Distribution of 125I‐Tyr1‐Somatostatin Binding Sites in Rat Brain
Authors: Epelbaum J. , Arancibia L. Tapia , Kordon C. , Enjalbert A.
Published: October 2006

Abstract: 125I‐Tyr1‐somatostatin binds reversibly, in a saturable manner, and with high affinity to membranes from rat brain. Kinetic and saturation data measured at equilibrium lead to KDvalues of 0.4 nM for cortical membranes. The binding is not affected significantly by seven neuropeptides and drugs unrelated structurally to somatostatin (SRIF) while native SRIF, Tyr1‐SRIF, and D‐Trp8‐D‐Cys14‐SRIF displace 125I‐Tyr1‐SRIF in a dose‐dependent manner, with Ki of 0.23 nM, 0.90 nM, and 0.11 nM, respectively. Binding sites for 125I‐Tyr1‐SRIF were found in 9 out of 11 central structures; there was a significant correlation between binding capacity and endogenous SRIF levels measured by radioimmunoassay. In each of the two structures containing the most binding sites, the cortex and the preoptic area, Scatchard analysis suggests a single population of sites with apparent affinities of 0.8 nM and 1.4 nM, respectively. Subcellular fractionation of these two regions reveals that more than 60% of 125I‐Tyr1‐SRIF specific binding of the homogenate is found in the crude mitochondrial pellet (P2), which contains synaptosomes. When P2 is further fractionated on a discontinuous sucrose gradient, most of the initial P2 binding is recovered from membrane fractions. Each of nine SRIF analogs, with a single alanine substitution, displaces 125I‐Tyr1‐SRIF binding on cortical membranes in the same order of potency as on adenohypophyseal membranes (r= 0.84). The data demonstrate the presence of SRIF binding sites in the rat brain, with kinetic characteristics comparable to those found in the adenohypophysis, and they provide a biochemical basis for the multiple functions of SRIF in brain.
Opiate Receptor: Multiple Effects of Metal Ions
Authors: Sadée W. , Pfeiffer A. , Herz A.
Published: October 2006

Abstract: The opiate antagonist [3H]diprenorphine ([3H]dip), a universal ligand at the μ, δ, and k opiate receptor subtypes, was used to study the effects of Ca‐II, Cu‐II, Mg‐II, Mn‐II, and Na+ on the rat cerebral opiate receptor. Two categories of effects were observed: (a) those on the binding rate constants and (b) those on binding capacity. (a) Sodium ions increased on‐ and off‐rates on [3H]dip with a rather small net change in receptor affinity. The effects of Na+ and the divalent ions Ca‐II, Mg‐II, and Mn‐II were antagonistic to each other. Ca‐II, Mg‐II, and the more effective Mn‐II decreased receptor association and dissociation rates, again with minimal changes in the overall binding affinity in washed membrane homogenates. Previous studies using equilibrium binding analysis alone failed to detect changes in [3H]dip binding kinetics caused by these metal ions. In untreated rat brain homogenates, however, Ca‐II (and to a lesser extent Mg‐II) decreased [3H]dip binding, an effect distinct from that on the binding rate constants in washed membrane homogenates. (b) In untreated, Tris‐buffer homogenates not containing external metal ions, a gradual decline in [3H]dip binding was observed. Cu‐II or an equivalent endogenous divalent metal ion was identified as a causative factor, and Mn‐II partially reversed this effect. Moreover, the addition of Mn‐II stabilized the [3H]dip binding sites at very low concentrations of the metal (nM to μM range) that did not change the binding rate constants and that were in the physiological range of Mn‐II in rat brain. This unique effect of Mn‐II may represent a physiological function in the regulation of the opiate receptor that is not shared by Mg‐II and Ca‐II. The opposite effects of Cu‐II and Mn‐II on the in vitro receptor stability may be related to their opposite pharmacological effect in vivo. Finally, multiple changes of the effects of the tested metal ions on [3H]dip binding were observed during in vitro membrane homogenate dilution, centrifugation, and washing. These changes indicate that the opiate receptor complex as it exists in vivo may lose some of its functions and control mechanisms in vitro.
Changes in Acetylcholinesterase Molecular Forms During the Embryonic Development of Torpedo marmorata
Authors: Witzemann Veit , Boustead Catherine
Published: October 2006

Abstract: Multiple molecular forms of acetylcholinesterase from electric organ and electric lobe of Torpedo marmorata were examined at various developmental stages by sucrose density sedimentation. Four major forms were characterized by their apparent sedimentation coefficients of 6 S, 11 S, 13 S, and 17 S. Embryonic lobe possessed at early stages predominantly the 11 S form. With maturation the 17 S form became the most abundant. The early embryonic stages of the electric organ were characterized by predominating amounts of 6 S and 11 S forms. With differentiation of the postsynaptic membrane of the developing electrocytes, 13 S and 17 S forms replaced the slower‐sedimenting forms. Concomitant with the formation of synaptic contacts, a transient increase in the 13 S form was followed by a dramatic accumulation of rapid‐sedimenting 17 S form. The establishment of fully functional synapses was accompanied by an increase in the amount of the hydrophobic 6 S form. At birth, equal amounts of 6 S and 17 S form were found, with the other forms present in only trace amounts. The observed characteristic changes correlated with morphological and physiological events, indicating a close functional relationship between the accumulation of the 17 S form and synapse formation and the accumulation of the 6 S form and onset of function.
Antiganglioside Antibodies Inhibit Neuritic Outgrowth from Regenerating Goldfish Retinal Explants
Authors: Spirman Nurit , Sela Ben‐Ami , Schwartz Michal
Published: October 2006

Abstract: Antibodies elicited in rabbits against bovine brain gangliosides were applied to regenerating retinal explants to examine the role of gangliosides in the trophic effect responsible for the induction of outgrowth. The results indicate that antibodies specific to gangliosides block the neuritic outgrowth from the regenerating retinal explants. It is inferred that gangliosides function as receptors on the cell surface of the retinal explants that interact with the trophic substances inducing the outgrowth. The relevance of gangliosides to the mechanism of regeneration and development induced by trophic factors is discussed.
Alterations of Lipid Metabolism in Response to Nerve Growth Factor
Authors: Traynor Alexis E. , Schubert David , Allen W. Ross
Published: October 2006

Abstract: In response to nerve growth factor (NGF), clonal pheochromocytoma cells flatten and extend neurites capable of making functional synapses. Although no significant changes in overall phospholipid composition occur in the presence of NGF, there is increased incorporation of 32PO4 into phosphatidylinositol and phosphatidic acid within 10 min after the addition of NGF. NGF stimulates the incorporation of 32PO4 into other lipids, such as phosphatidylcholine, to a lesser extent. The kinetics of the NGF‐induced phosphatidylinositol responses are different when the cells are in suspension from when they are attached to culture dishes. These changes in phospholipid metabolism are discussed with respect to their role in NGF‐induced nerve differentiation.
Neurochemical Studies of the Mesolimbic Dopaminergic Pathway: Glycinergic Mechanisms and Glycinergic‐Dopaminergic Interactions in the Rat Ventral Tegmentum
Authors: Gundlach A. L. , Beart P. M.
Published: October 2006

Abstract: The rat ventral tegmentum (containing somata and dendrites of mesolimbic dopaminergic neurones) contained 1.3 μmnol/g wet weight of glycine. Slices of ventral tegmentum accumulated exogenous [3H]glycine by an energy‐, temperature‐ and sodium‐dependent mechanism. The uptake was mediated by two different transport systems; one system with relatively low affinity for glycine (Km∼400 μm) and the other a higher affinity for glycine (Km∼ 10 μm). Small amino acid analogues of glycine inhibited the uptake process, the most potent being taurine and β‐alanine (47% and 44% inhibition, respectively, at 1 mm). Release of exogenous [3H]glycine by elevated potassium and by protoveratrine A was calcium‐dependent and tetrodotoxin‐sensitive. Glycine (500 μm‐2 mm) potentiated the protoveratrine A‐induced release of exogenous [3H]dopamine from slices of ventral tegmentum; this potentiation was blocked by strychnine (10 μm). A convulsant dose of strychnine elevated the concentration of 3,4‐dihydroxyphenylacetic acid in the ventral tegmentum. Glycine is likely to be a transmitter in the ventral tegmentum and to have a role regulating the activity of somatodendritic regions of mesolimbic dopaminergic neurones.
The Binding of [3H]AMPA, a Structural Analogue of Glutamic Acid, to Rat Brain Membranes
Authors: Honoré Tage , Lauridsen Jørn , Krogsgaard‐Larsen Povl
Published: October 2006

Abstract: Binding of [3H]AMPA to rat brain membranes was investigated. The binding was saturable and reversible at physiological pH. Computer‐aided Scatchard analysis of the binding data, as determined by using l‐glutamic acid (l‐GLU) to define nonspecific binding, suggested the presence of two independent binding sites, with KDs of 9 and 2440 nm, respectively. Additional freezing, thawing and washing sequences gave membranes with only one binding site, with a KD of 278 nm. [3H]AMPA binding exhibited the highest blevel in striatal membranes. A series of analogues of GLU and aspartic acid (ASP) were tested as inhibitors of [3H]AMPA binding. l‐ASP and compounds which interact predominantly with N‐methyl‐d‐aspartic acid (NMDA) receptor sites were inactive as inhibitors of [3H]AMPA binding, whereas l‐GLU and compounds which interact predominantly with glutamic acid diethyl ester receptor sites were inhibitors with the same order of potency as that shown by the excitatory action in vivo. The result suggests that [3H]AMPA might represent binding to an excitatory GLU receptor.
Cerebroside Sulfotransferase in Golgi‐Enriched Fractions from Rat Brain
Authors: Benjamins Joyce A. , Hadden Timothy , Skoff Robert P.
Published: October 2006

Abstract: Golgi‐enriched fractions were prepared from brainstems of 17‐day‐old rats by first floating off myelin, then fractionating the remaining pellet by a series of differential and density gradient centrifugations in sucrose. Fractions enriched in Golgi membranes were recovered at 0.46/0.76 m and 0.76/0.87 m interfaces on the final sucrose gradient as indicated by morphology and the biochemical markers thiamine pyrophosphatase and [3H]fucose‐labeled glycoprotein. Morphology of the two fractions indicated very little contamination with myelin lamellae; however, the presence of significant levels of 2′, 3′‐cyclic nucleotidase in the lighter fraction suggested a contribution from oligodendroglial or myelin‐related membranes. Cerebroside sulfotransferase was highly enriched in the lighter Golgi‐enriched fraction relative to the denser fraction, the post‐34, 880 x g microsomes, and the myelin‐like fraction. In contrast, ceramide galactosyl transferase was more evenly distributed among the fractions. Our results show a more highly localized distribution of sulfatide synthesis than of galactocerebroside synthesis, probably in Golgi membranes or oligodendroglia‐related membranes with similar properties.
Homocarnosinosis: Hypercarnosinuria
Authors: Lunde Hilde , Sjaastad Ottar , Gjessing Leiv
Published: October 2006

Abstract: Homocarnosine (γ‐aminobutyrylhistidine) is a brain‐specific dipeptide. Homocarnosinosis is a familial metabolic disorder in which spastic paraplegia, progressive mental deficiency, and retinal pigmentation coexist with increased CSF homocarnosine levels, i.e. approximately 20 times higher than the mean control level. In the present study, the urinary excretion of carnosine (β‐alanylhistidine) and anserine (β‐alanyl‐1‐methylhistidine) was determined in patients with homocarnosinosis and in their close relatives. Both the patients and their relatives were also loaded with chicken meat, which is rich in anserine and carnosine. The results were compared with those obtained in childhood hypercarnosinuria with serum carnosinase deficiency. Somewhat surprisingly, patients with homocarnosinosis were also shown to have hypercarnosinuria. Chicken meat loading in healthy individuals results in increased excretion of carnosine and anserine and, in addition, 1‐methylhistidine in the urine. Homocarnosinosis patients and patients with serum carnosinase deficiency also showed an increased excretion of carnosine and anserine, but 1‐methylhistidine was not detected in serum carnosinase deficiency, and it was present only in very small amounts in homocarnosinosis. This defect seems to be due to lack of the hydrolyzing enzyme activity. The biochemical and clinical similarities between adult homocarnosinosis and infantile serum carnosinase deficiency are intriguing. A complete insight into the relationship between them must await further investigation.
Characterization of the Blood‐Brain Barrier: Protein Composition of the Capillary Endothelial Cell Membrane
Authors: Lidinsky William A. , Drewes Lester R.
Published: October 2006

Abstract: Microvessels were isolated from canine cerebral cortex, and the composition of the endothelial cell membrane was investigated. Endothelial. cell msmtbranes were separated from the surrounding basement mem brane, solubilized, and subjected to sodium dodecyl sul fate‐polyacrylamide gel electrophoresis in 12% gels Staining with Coomassie Blue revealed a characteristic banding pattern of at least 12 major proteins with ap parent molecular weights between 14,000 and 250,000 When proteins from red blood cell ghosts were run si multaneously, no similarities were observed, except foi proteins at apparent molecular weights of 43,000 (band 3) and 35,000 (band 4). These two proteins migrated exactly to the positions of the erythrocyte proteins actin and gly ceraldehyde 3‐phosphate dehydrogenase, respectively Membrane glycoproteins in gels were also examined by the use of fluorescent lectins. Of the fluorescein isothiocyanate‐conjugated (FITC) lectins tested, only FITC concanavalin A had an affinity for any membrane components. Diazotized [125I]iodosulfanilic acid, a membrane‐impermeable reagent, was used to label the internal (lumen) cell surface and the external (antilumen) cell surface. Autoradiography and determination of radioactivity levels in gel slices showed that several proteins were specifically labeled, and that major differences in radioactivity of proteins existed in internal and external labeling experiments. It is concluded that the protein composition of the luminal membrane is different from that of the an‐tiluminal membrane. In addition to the results obtained, the above procedures provide a model system for the further investigation of endothelial cell membrane proteins and the blood‐brain barrier.
Age and Strain Comparisons of Neurotransmitter Synthetic Enzyme Activities in the Mouse
Authors: Waller Steven B. , Ingram Donald K. , Reynolds Mark A. , London Edythe D.
Published: October 2006

Abstract: Activities of the neurotransmitter synthetic enzymes, choline acetyltransferase (EC 2.3.1.6; ChAT), glutamic acid decarboxylase (EC 4.1.1.15; GAD), and tyrosine hydroxylase (EC 1.14.3.2; TH), were assayed in four brain regions of A/J and C57BL/6J mice at three ages (4. 18, and 24 months). The brain regions assayed were the fronto‐parietal cortex, hippocampus, striatum, and cerebellum. Strain effects: In some brain regions, at several ages, ChAT activity did not differ among the two srains. However, ChAT was higher in the C57BL/6J strain in the cortex at 18 months, the hippocampus at 18 and 24 months, the striatum at 24 months, and the cerebellum at 4 months. The reverse was true in the cerebellum at 24 months, where ChAT was higher in A/J mice. GAD activity in C57BL/6J mice compared to that of A/J mice was higher in the striatum and cortex, and lower in the hippocampus and cerebellum. TH activities in all four regions were generally higher in C57BL/6J mice than in A. J mice. Age effects: Age differences in enzyme activities varied with the genetic strain. ChAT activity generally was higher in brain regions of older mice of both strains. GAD activity was lower in some brain regions of older mice compared to those of younger mice (A/J striatum, C57BL/6J cortex), but higher in other brain regions of older mice compared to those in younger mice (C57BL/6J striatum, hippocampus of both strains). Whereas there were no age‐related differences in striatal TH in either strain, TH activity was higher in other brain regions of older mice (A/J cortex, cerebellum and hippocampus; C57BL/6J cerebellum). In C57BL/6J mice, cortical TH was higher at 18 months than at 4 months, but lower at 24 months than at 18 months. Higher activities of hippocampal ChAT and GAD and cerebellar TH in older C57BL/6J mice reflected increases in Vmax, with no age differences in Km values for substrates. These findings indicate that neurochemical profiles as well as the effects of age on these profiles vary with genetic strain.
Labelling of “Peripheral‐Type” Benzodiazepine Binding Sites in the Rat Brain By Using [3H]PK 11195, an Isoquinoline Carboxamide Derivative: Kinetic Studies and Autoradiographic Localization
Authors: Benavides J. , Quarteronet D. , Imbault F. , Malgouris C. , Uzan A. , Renault C. , Dubroeucq M. C. , Gueremy C. , Fur G. Le
Published: October 2006

Abstract: PK 11195 [1‐(2‐chlorophenyl)‐N‐methyl‐N‐(1‐methylpropyl)‐3‐isoquinolinecarboxamide] is a new ligand for the “peripheral‐type” benzodiazepine binding sites, chemically unrelated to benzodiazepines. It displaces with a very high potency (IC50× 10−9M) [3H]‐RO5–4864 (a benzodiazepine which specifically labels the peripheral‐type sites) from its binding sites. [3H]PK 11195 binds to a membrane fraction from rat brain cortex and rat olfactory bulb in a saturable and reversible manner with a very high affinity (KD= 10−9M). The number of maximal binding sites was ten times greater in the olfactory bulb than in the brain cortex. The order of potency of several compounds as displacers at 25°C (PK 11195 > RO5–4864 > diazepam > dipyridamole > clonazepam) demonstrates that [3H]PK 11195 binds to the peripheral‐type benzodiazepine binding sites. The KD value for the [3H]PK 11195 binding is not affected by temperature changes, whereas RO5–4864 and diazepam affinities decrease with increasing temperatures. Autoradiographic images of [3H]PK 11195 binding to rat brain sections show that binding sites are mainly localized in the olfactory bulb, median eminence, choroid plexus, and ependyma. This ligand could be a useful tool to elucidate the physiological and pharmacological relevance of these binding sites.
Effect of 2‐Amino‐7‐Phosphonoheptanoic Acid on Regional Brain Amino Acid Levels in Fed and Fasted Rodents
Authors: Westerberg Eva , Chapman Astrid G. , Meldrum Brian S.
Published: October 2006

Abstract: 2‐Amino‐7‐phosphonoheptanoic acid, an antagonist of excitation caused by dicarboxylic amino acids with a selective action on N‐methyl‐d‐aspartate receptors, has been administered in an anticonvulsant dose (1 mmol/kg i.p.) to fed or fasted rats and mice. The drug impaired motor activity in fasted mice. Glucose and amino acids were determined in dissected regions of brain fixed by microwave irradiation. Glucose content was low in the brains of fasted rats and mice but was restored to normal (fed) concentration 45 min after the administration of 2‐amino‐7‐phosphonoheptanoic acid in fasted mice. In fed animals, 2‐amino‐7‐phosphonoheptanoic acid did not change brain aspartate concentration. In fasted animals, aspartate concentration was raised in most brain regions. In fasted rats and mice, 2‐amino‐7‐phosphonoheptanoic acid significantly increased glutamine in rat cortex and mouse striatum, decreased glutamate content in rat striatum, and decreased aspartate concentration in all regions except mouse cortex and striatum. GABA levels were significantly decreased in rat striatum and hippocampus. These changes are consistent with an increased synaptic release of glutamate and aspartate following blockage of their post‐synaptic action at selected sites.
Solid‐Phase Radioimmunoassay for Substance P
Authors: Oblin Andre , Zivkovic Branimir
Published: October 2006

Abstract: The solid‐phase immunoassay for quantification of substance P has been developed. The assay is based on the repartition of anti‐substance P antibodies between the insoluble phase‐immobilized substance P and the free peptide. The immobilized substance P‐antibody complex is then quantified with 125I‐protein A. The method allowed detection of 10 pg of substance P. The values of substance P concentration obtained by the present method in different regions of the rat brain were comparable to those obtained by standard radioimmunoassay with 125I‐tyr‐8‐substance P as tracer. The described solid‐phase radioimmunoassay is a simple, sensitive, and reliable technique for quantification of substance P‐like immunoreactivity in biological samples.
Serotonin‐Elicited Amplification of Adenylate Cyclase Activity in Hippocampal Membranes from Adult Rat
Authors: Barbaccia M. L. , Brunelle N. , Chuang D.‐M. , Costa E.
Published: October 2006

The activity of the adenylate cyclase located in membranes prepared from hippocampus of adult rat can be stimulated by serotonin (5‐HT) (Ka= 4 x 10‐7M). The maximal effect is obtained with 10 μM 5‐HT. Freezing of the tissue decreases the 5‐HT stimulation; this stimulation is optimal in the presence of 82.5 mM Tris‐maleate buffer (pH 7.4) and 50 μM GTP. The adenylate cyclase activity of membranes prepared from cortex, hypothalamus, and colliculi of adult rats is not significantly stimulated by 5‐HT. Dopamine (DA) also stimulates adenylate cyclase located in hippocampal membranes; its effect can be blocked by haloperidol (10‐6 M), which fails to inhibit 5‐HT stimulation. Moreover, p‐chlorophenylalanine treatment for 2 weeks or selective lesion of 5‐HT axons afferent to the hippocampus increases the Vmax of 5‐HT stimulation, but fails to change that of DA stimulation. The 5‐HT stimulation can be inhibited by metergoline, spiroperidol, and pizotyline (10‐6 M), but not by the same concentrations of mianserin, ketanserine, alprenolol, phenoxybenzamine, and mepyramine. The 5‐HT stimulation of adenylate cyclase of hippocampal membranes can be mimicked by tryptamine, 5‐methoxytryptamine, bufotenine, and to a lesser extent by LSD; N‐methyltryptamine, N‐methyltryptophan, and 5‐hydroxytryptophan are inactive. Studies with kainic acid suggest that the 5‐HT recognition site (5‐HT1) linked to adenylate cyclase is located on the membrane of intrinsic hippocampal neurons.
Specific Binding of [11C]Spiroperidol in Rat Brain In Vivo
Authors: Arnett Carroll D. , Fowler Joanna S. , Wolf Alfred P. , MacGregor Robert R.
Published: October 2006

Abstract: Spiroperidol labeled with carbon‐11, a shortlived positron‐emitting radionuclide, was used to determine the time course of specific binding of this radio‐ligand to the neuroleptic receptor in vivo in the rat. The three major brain pools‐specifically bound, non‐specifically bound and free (unbound)‐were determined over a 60‐min time course by a rapid filtration technique, utilizing (‐)‐ and (+)‐butaclamol pretreatments to assess total and nonspecifically bound activities, respectively, in striatum and cerebellum. The ratio of specifically to nonspecifically bound pools in the striatum was 4.1 at 30 min and 5.1 at 60 min. Thus [11C]spiroperidol may be useful for labeling neuroleptic receptors in vivo for serial studies using positron emission transaxial tomography.
Thyrotropin‐Releasing Hormone and Its Analog MK‐771 Increase the Cerebroventricular Perfusate Content of Dihydroxyphenylacetic Acid
Authors: Nielsen Jann A. , Moore Kenneth E.
Published: October 2006

Abstract: The effects of thyrotropin‐releasing hormone (TRH) and its synthetic analog, pyro‐2‐aminoadipyl‐his‐tidyl‐thiazolidine‐4‐carboxamide (MK‐771), were determined on the efflux of dihydroxyphenylacetic acid (DOPAC) collected from push‐pull cannulae chronically implanted into the lateral cerebral ventricles of rats. Intracerebroventricular and intraperitoneal injections of both peptides increased the efflux of DOPAC. These results suggest that TRH and MK‐771 increase the activity of dopaminergic neurons that terminate in periventricular regions.
Myelin Gangliosides in Developing Rats: The Influence of Maternal Ethanol Consumption
Authors: Gnaedinger Jean M. , Noronha Antonio B. , Druse Mary J.
Published: October 2006

Abstract: The present study examined myelin gangliosides in the developing offspring of rats that were pair‐fed control or ethanol liquid diets prior to and during gestation. Between 17 and 31 days of age, we observed an increase in the proportion of GM1 in myelin (from 15% to 38% of ganglioside sialic acid) and a decrease in the proportion of GT1b (from 26% to 4%). GM4 was detected at all ages examined. Between 17 and 31 days of age, there was an increase in the proportion of N‐acetylman‐nosamine‐derived radioactivity associated with GM1 (from 16% to 22%) and GM4 (from 5% to 13%), and a decrease in that associated with GT1b (from 24% to 4%). Small, but sygnificant (p < 0.05), developmentally related differences were found in GD2 and GD3. Detection of GM4 in myelin of young rats in the present study appears to depend on the use of nonpartitioning methods of ganglioside extraction. Although the distribution of myelin gangliosides and radioactivity was near‐normal in ethanol‐treated pups, there was a consistent decrease in the proportion and radioactivity associated with the major myelin ganglioside, GM1.
Sulfate Conjugation of Dopamine in Rat Brain: Regional Distribution of Activity and Evidence for Neuronal Localization
Authors: Rivett A. Jennifer , Francis Andrew , Whittemore Russell , Roth Jerome A.
Published: October 2006

Abstract: Brain tissue contains at least two forms of phenolsulfotransferase that are involved in the sulfate conjugation of biogenic amines and their metabolites. Two apparent Km values were obtained for p‐nitrophenol at pH 7.4 (0.6 μM and 0.3 mM) but only one enzyme had the capacity to conjugate dopamine (Km=130 μM). Dopamine sulfotransferase activity was found to vary 17‐fold in different brain regions, with the highest levels in diencephalon, hippocampus, and striatum. To determine the cellular localization of the enzymes, phenolsulfotransferase activity was measured in striatum following selective destruction of striatal neurons by stereotaxic injection of 2 μg kainic acid. Fourteen days after injection the catecholamine sulfotransferase activity in the lesioned striatum was reduced to approximately 40–50% of that in the control contralateral striatum. There was a statistically significant correlation between the ratio of lesioned to control activity for the sulfotransferase and the neuronal marker enzymes glutamate decarboxylase and neuron‐specific enolase. p‐Nitrophenol sulfotransferase activity was also decreased in the lesioned striatum. These results suggest that PST activity is present within the kainic acid‐sensitive neurons of the striatum. The regional variation in activity, together with the results of the kainic acid studies, suggest that sulfate conjugation of biogenic amines and their metabolites in brain may take place within specific types of neurons.