bluuebunny/crossref_metadata_2025_split huggingface dataset:
AN ADAPTATION OF THE PUSH‐PULL CANNULA METHOD TO STUDY THE IN VIVO RELEASE OF [3H]DOPAMINE SYNTHESIZED FROM [3H]TYROSINE IN THE CAT CAUDATE NUCLEUS: EFFECTS OF VARIOUS PHYSICAL AND PHARMACOLOGICAL TREATMENTS
Authors: Nieoullon A. , Cheramy A. , Glowinski J. 
Published: October 2006

Abstract— The release of [3H]dopamine ([3H]DA) continuously synthesized from l‐[3,5–3H]tyrosine from the caudate nucleus of the cat was estimated in halothane anaesthetized or‘encéphale isolé’animals. For this purpose, an improved superfusion cannula, avoiding tissue damage, was used. The best localization for the tip of the superfusion cannula was found first by determining the topographical distribution of endogenous DA within the caudate nucleus. A rostro‐caudal heterogenous distribution of the transmitter was detected.In perfusion experiments, l‐[3,5–3H]tyrosine was introduced continuously at a rate of 33μl/min. [3H]DA was the only catecholamine found in serial 15 min fractions as revealed by cochromatography. The spontaneous release of [3H]DA was greater in anaesthetized than in ‘encéphale isolé’ cats; it represented 150 and 100 times the blank value, respectively.Depolarization by K+ (30 mm) applied locally in the striatum or by electrical or mechanical stimulation of the substantia nigra caused a transitory increase in [3H]DA release. Conversely, a decrease in nerve activity induced by tetrodotoxin (5 × 10−‐7 m) or by electrocoagulation of the substantia nigra was associated with a decline in the amounts of [3H]DA in superfusates. A temporary reduction in [3H]DA release could also be obtained by a short‐lasting cooling block of the substantia nigra.As expected, d‐amphetamine (10−‐5 m) and benzotropine(10−‐7 m) added to the superfusing medium increased [3H]DA release.These pharmacological results, as well as the changes in [3H]DA release observed after various manipulations of the activity of dopaminergic neurones, confirms the validity and the high sensitivity of this approach.
GAMMA‐AMINOBUTYRIC ACID BINDING IN MAMMALIAN BRAIN: RECEPTOR‐LIKE SPECIFICITY OF SODIUM‐INDEPENDENT SITES
Authors: Greenlee Donald V. , Van Ness Paul C. , Olsen Richard W. 
Published: October 2006

AbstractThe binding of radioactive gamma‐aminobutyric acid to particulate fractions of mammalian brain was measured by a centrifugation assay, using repeatedly washed and frozen and thawed membranes and sodium‐free assay conditions. Studies of over 30 structural analogues indicated an excellent correlation between inhibition of gamma‐aminobutyric acid binding and activity as agonists or antagonists on gamma‐aminobutyric acid synapses as reported in the neurophysiology literature. In particular, binding was inhibited by low concentrations of the gamma‐aminobutyric acid receptor‐specific drugs muscimol, homotaurine, and isoguvacine, but very poorly by analogues such as 2,4‐diaminobutyric acid and nipecotic acid which specifically inhibit gamma‐aminobutyric acid transport but are inactive on synaptic receptors. Binding was inhibited by the synaptic antagonist bicuculline but not by picro‐toxinin. Thus, these binding sites show the chemical specificity required of physiological receptors for the neurotransmitter gamma‐aminobutyric acid.
MUSCIMOL UPTAKE, RELEASE AND BINDING IN RAT BRAIN SLICES
Authors: Johnston G. A. R. , Kennedy S. M. E. , Lodge D. 
Published: October 2006

Abstract— The GABA analogue, muscimol, was taken up relatively inefficiently compared to GABA by slices of rat cerebral cortex at 37 C. Muscimol uptake followed saturation kinetics (Km ImM. Vm 0.1 μmol g mini and showed an absolute dependence on sodium ions. The relative susceptibilities of muscimol uptake and GABA high affinity uptake to a variety of inhibitors, including (‐)‐nipecotic acid. (+)‐2.4‐diaminobutyric acid and arecaidine, and the stimulation of muscimol efflux by 50μM‐GABA, suggest that muscimol and GABA share some common transport carriers. Since L‐histidine inhibited muscimol uptake hut not GABA high affinity uptake, at least part of the observed muscimol uptake may be mediated by the 'small basic’amino acid transport system. Muscimol appeared to he taken up into nerve terminals, since uptake was inhibited by the neuronal uptake inhibitor cis‐3‐aminocyclohexanecarboxylic acid but not by the glial uptake inhibitor β‐alanine. Muscimol efflux was stimulated in a calcium‐dependent manner by an increased potassium ion concentration.Sodium‐independent binding of muscimol was observed in slices of rat cerebral cortex at 4 C. Binding could be inhibited by a variety of substances. including GABA, isoguvacine and (+)‐bicuculline methochloride, which are known to inhibit the binding of muscimol to putative GABA receptors associated with synaptic membranes purified from rat brain.
BIOCHEMICAL STUDIES OF NERVE EXCITABILITY: THE USE OF PROTEIN MODIFYING REAGENTS FOR CHARACTERIZING SITES INVOLVED IN NERVE EXCITATION
Authors: Baumgold Jesse , Matsumoto Gen , Tasaki Ichiji 
Published: October 2006

Abstract—A variety of protein modifying reagents were applied to crab nerves extracellularly while monitoring the action potentials. These reagents were also applied to squid giant axons intracellularly, while monitoring the action potentials, and for some compounds the membrane resistance and resting membrane potential. The effects of modifying sulfhydryl, imidazole, amino, and methionine groups on the nerve excitability were examined. These studies revealed that imidazole and sulfhydryl groups are present on the axoplasmic side of the axolemma and that chemical modification of these groups leads to block of nerve conduction. When various reagents which modify amino groups were applied either from the inside of squid axons or to the outside of crab nerves, the excitability was not usually affected. The suppression of excitability due to the effect of some of these amino reagents could be attributed to the modification of groups other than amino groups. The hydrolytic action of cyanogen bromide was found to be effective in bringing about conduction block, suggesting that there exist accessible methionine groups in protein molecules which must remain intact in order to maintain nerve conduction.
SUBCELLULAR DISTRIBUTION OF DOPAMINE IN SUBSTANTIA NIGRA OF THE RAT BRAIN: EFFECTS OF γ‐BUTYROLACTONE AND DESTRUCTION OF NORADRENERGIC AFFERENTS SUGGEST FORMATION OF PARTICLES FROM DENDRITES1
Authors: Hefti F. , Lichtensteiger W. 
Published: October 2006

Abstract— The subcellular distribution of dopamine (DA) in substantia nigra from individual male rats was studied with a fractionation procedure on microscale. After differential centrifugation the distribution of DA coincided with that of noradrenaline (NA) which can serve as a marker for synaptosomes in this area. The proportion of DA/NA concentrations was about 1–2 in most fractions. Sixty per cent of nigral DA was found in P2 (17,000 g). When P, was layered on a continuous density gradient, DA and NA peaked at the density of 1.0–1.2 M‐sucrose. Since DA‐containing particles covered a relatively broad range on this gradient, particles between 0.7 and 1.3 M‐sucrose were collected with a discontinuous density gradient. Sixty per cent of DA from P2, was found in this subfraction.The particles containing DA could have been derived from dendrites or axon collaterals of nigrostriatal neurones or represent precursor DA in noradrenergic (NA) terminals. The role of collaterals was investigated by comparing the effect of γ‐butyrolactone (GBL, 750 mg/kg, 1 h) on DA concentrations in subcellular fractions from substantia nigra and caudate‐putamen. In caudate‐putamen, GBL produced a marked increase of DA in total homogenates and subcellular fractions except P3, whereas DA concentrations remained unchanged in all fractions from substantia nigra. This speaks against a contribution from DA terminals.The proportion of DA contained as precursor in NA terminals was analysed after destruction of the NA input to substantia nigra by two methods. A single injection of 6‐hydroxydopamine into the IV ventricle decreased nigral NA by 5574, DA only by 17%. Unilateral electrolytic lesions in the pontine tegmentum affected NA concentrations in homogenates and fraction P2 of the ipsilateral substantia nigra to a much greater extent than DA. From the results obtained with the two approaches, it is estimated that precursor DA in particulate fractions does not exceed 10%.Our observations indicate that dendrites of the DA neurones in substantia nigra can form particles which behave like synaptosomes on density gradients centrifugation; they may be termed ‘dendrosomes’. According to the proportion of DA found in the particulate fractions at least 4040% of nigral DA appear to be localised in dendrites.
THE SYNTHESIS OF CHOLINE PHOSPHOGLYCERIDES IN THE GIANT FIBRE SYSTEM OF THE SQUID
Authors: Brunetti Marina , Giuditta A. , Porcellati G. 
Published: October 2006

Abstract—The mechanisms and pathways of synthesis of phosphatidylcholine in the giant fibre system of the squid (Loligo vulgaris) have been examined by incubating the stellate ganglion‐nerve preparation or its separated compartments in an artificial bathing solution with labelled choline. Other experiments were done by dissecting the whole stellate ganglion into axoplasm, axon sheath, giant fibre lobe, small fibres and ganglion residue, after incubation. The initial rate of choline incorporation into choline phosphoglycerides was severalfold higher in the lobe than in the axon. Higher lipid radioactivity was recovered in the axon sheath as compared to the axoplasm, and in the small fibres as compared to the ganglion residue which contains its cell bodies. The production of phosphorylcholine and CDP‐choline in the intact ganglion‐nerve preparation during incubation with choline points to the occurrence of the net synthesis pathway for phosphatidylcholine in this material. Base‐exchange activity was also observed in the axon and giant fibre lobe preparations in vitro, but no indication can yet be given whether it also takes place in intact preparations.Electrical stimulation and‘depolarizing’conditions enhance choline phosphorylation in the squid axon and lobe, but decrease phosphatidylcholine labelling.
IN VIVO RELEASE OF ENDOGENOUS GABA FROM RAT SUBSTANTIA NIGRA MEASURED BY A NOVEL METHOD
Authors: Van der Heyden J. A. M. , Venema K. , Korf J. 
Published: October 2006

Abstract—A sensitive GABA assay using HPLC coupled with fluorimetric detection with o‐phthalaldehyde is described. GABA, lysine and ethanolamine can be measured within approx 12 min. The detection limits for these compounds (signal/noise = 3) is 0.67 pmol, 1.8 pmol and 0.73 pmol respectively. Using this assay the in vivo release of GABA from rat substantia nigra was studied with a push‐pull perfusion technique.A pronounced increase in the rate of endogenous GABA release was observed after addition of depolarizing amounts of K+ to the perfusion medium, whereas the concentrations of lysine and ethanolamine in the perfusate did not change. This enhanced release of GABA was not diminished after omission of Ca2+ and Mg2+ from the medium. Increasing the Mg2+ concentration and leaving out Ca2+ however, resulted in a marked depression in the K+‐induced GABA release.Electrical stimulation of the striatum also produced an increase in release of GABA from the substantia nigra.Inhibition of glutamic acid decarboxylase (with 3‐mercaptopropionic acid) caused an immediate decrease in GABA release. Inhibition of GABA transminase (with aminooxyacetic acid) leads to an increased release of GABA after approx 15 min.These findings suggest that the technique is suitable for measuring neuronal release of endogenous GABA in vivo
ON THE COMPOSITION AND STRUCTURE OF INDIVIDUAL GANGLIOSIDES FROM THE BRAIN OF ELASMOBRANCHES
Authors: Avrova N. F. , Li Y.‐T. , Obukhova E. L. 
Published: October 2006

AbstractGangliosides with a short carbohydrate chain: II3(NeuAc)2‐LacCer, II3(NeuAc)2‐GgOse3Cer, II3(NeuAc)3‐LacCer, II3NeuAc‐LacCer, and II3NeuAC‐GgOse3 Cer, were found to be predominant in the brain of 8 species of cartilaginous fish, elasmobranches. N‐acetylneuraminic acid was the only sialic acid found in these gangliosides, the N‐glycolyl derivative being practically absent. 4‐Sphingenine was shown to be the predominant sphingoid in elasmobranch brain gangliosides.The sequential enzymatic hydrolysis of II3(NeuAc)2 ‐LacCer from shark and ray brain by acylneur‐aminyl hydrolase (EC 3.2.1.18) and β‐D‐galactoside‐galactohydrolase (EC 3.2.1.23), as well as permethylation studies, provide further evidence for the following structure of this major elasmobranch brain ganglioside:
[3H]HARMALINE AS A SPECIFIC LIGAND OF MAO A—I. PROPERTIES OF THE ACTIVE SITE OF MAO A FROM RAT AND BOVINE BRAINS
Authors: Nelson D. L. , Herbet A. , Pétillot Y. , Pichat L. , Glowinski J. , Hamon M. 
Published: October 2006

AbstractA high‐affinity (Kd= 5.9 nM) specific binding site for [3H]harmaline was detected in membranes from rat and bovine brains. Studies of the regional and subcellular distributions of this binding indicated its close association with monoamine oxidase type A activity (MAO A) measured with [3H]serotonin ([3H]5‐HT) as the substrate. Maximal binding capacity and MAO A activity were found in mitochondrial enriched fractions. Mitochondria of synaptosomal or extra‐synaptosomal origin exhibited very similar properties with respect to [3H]harmaline binding characteristics and MAO A activity.Among psychoactive drugs, only monoamine oxidase inhibitors (MAO I) prevented the specific binding of [3H]harmaline. Logit‐log inhibition curves of binding by MAO I gave only one slope which was not significantly different from 1.0, suggesting the existence of only 1 category of specific sites for [3H]harmaline in the membrane preparations from rat and bovine brains. Consistent with the preferential inhibition of MAO A by harmaline, other MAO I of this class, i.e. clorgyline and Lilly 51641, were 102‐2 × 103 times more efficient than deprenyl and pargyline, two inhibitors of MAO type B, in displacing [3H]harmaline from its specific binding site. Ki and IC50 values for the inhibition of [3H]harmaline binding by MAO I and MAO substrates (tryptamine, 5‐HT, norepinephrine) were almost identical with those characterizing their action on MAO A activity with [3H]5‐HT as the substrate. In conclusion, the specific binding site for [3H]harmaline exhibited all the expected properties of the active site of MAO A. Like the technique of precipitation with a specific antibody, binding of [3H]harmaline should be of great help for studying the structural characteristics of the active site of MAO A and determining the number of MAO molecules in tissues under various physiological conditions.
TYROSINE HYDROXYLASE ACTIVITY IN NORADRENERGIC NEURONS OF THE LOCUS COERULEUS AFTER RESERPINE ADMINISTRATION: SEQUENTIAL INCREASE IN CELL BODIES AND NERVE TERMINALS
Authors: Zigmond R. E. 
Published: October 2006

AbstractThe effect of a single systemic injection of reserpine on tyrosine hydroxylase activity in the locus coeruleus, cerebellum, hypothalamus, and hippocampus was examined. Increases in enzyme activity were seen in all four brain areas; the time‐course of the changes, however, was different in each case. In the locus coeruleus the maximum change in enzyme activity was seen 3 days after drug administration; in the cerebellum, 7‐11 days; in the hypothalamus, 8‐11 days; and in the hippocampus, 21 days. Since tyrosine hydroxylase in the cerebellum and hippocampus is present in terminals of neurons whose cell bodies are located in the locus coeruleus, the delayed increase in enzyme activity in cerebellum and hippocampus probably depends upon the slow rate of transport of TH molecules in these neurons.
MAXIMUM ACTIVITIES, PROPERTIES AND DISTRIBUTION OF 5’NUCLEOTIDASE, ADENOSINE KINASE AND ADENOSINE DEAMINASE IN RAT AND HUMAN BRAIN
Authors: Phillips E. , Newsholme E. A. 
Published: October 2006

Abstract— The maximum activities of 5’nucleotidase, adenosine kinase and adenosine deaminase have been measured in several areas of rat and human brain. There is no major difference between the activities of nucleotidase and kinase between rat and human brain, but the activity of deaminase is considerably higher in human brain. The activities of all these enzymes are similar in three areas of rat brain and nine areas of human brain, except for hind brain of the human, which has a low activity of adenosine deaminase. This variation may indicate the existence of different steady‐state concentrations of adenosine in certain areas of the brain.Subcellular fractionation of different areas of rat brain showed that, whereas adenosine kinase and deaminase activities were located mainly in the soluble fractions, 5’nucleotidase was present in all subcellular fractions (i.e. membrane, synaptosomal, mitochondrial and soluble). In particular, there was no major localisation within the synaptosomal fraction. Thus it is unlikely that the regulation of the activities of these enzymes is dependent upon changes within a specific compartment (e.g. synaptosomes) in the brain.
DEVELOPMENTAL CHANGES IN LEVELS AND FORMS OF CHOLINESTERASES IN MUSCLES OF NORMAL AND DYSTROPHIC CHICKENS
Authors: Lyles Joan M. , Silman Israel , Barnard Eric A. 
Published: October 2006

Abstract— Acetylcholinesterase (AChE) and pseudocholinesterase (°ChE) were studied in vivo and during the first several months of development of pectoral and posterior latissimi dorsi (PLD) muscles in normal and dystrophic chickens. Muscle extracts were prepared in a high ionic strength‐nonionic detergent medium in the presence of protease inhibitors, in order to obtain complete solubilization and to prevent degradation of intrinsic molecular forms of both enzymes.In both normal and dystrophic pectoral muscles levels of AChE and °ChE increase rapidly in vivo, °ChE accounting for 5–10% of total cholinesterase activity. In the normal pectoral muscle the concentration of both enzymes drops rapidly after hatching with increasing muscle mass; total AChE per muscle remains relatively constant for 30 days post‐hatch. In the dystrophic pectoral muscle both AChE and °ChE accumulate after hatching, resulting in greatly elevated levels (approx 10–25‐fold) of both enzymes throughout the period studied.Multiple molecular forms of AChE and °ChE are observed in the pectoral muscle by sucrose gradient centrifugation. Four principal forms are distinguished: two light (L1, L2), one medium (M), and one heavy (H2). The °ChE forms are 0.5–1.0 S units lighter than the corresponding AChE forms. L2 is the predominant light form of AChE, whereas L1 is the major light °ChE form detected. The lighter forms of AChE predominate in normal and dystrophic embryonic pectoral muscle at day 14, being replaced by the H2 form by day 19. H2 is the major °ChE form detected at day 19. After hatching, H2 AChE is the predominant form found in both of the normal muscles studied. In the dystrophic pectoral muscle, progressive accumulation of the L2 form of AChE is detected as early as day 4 post‐hatch; this form eventually becomes predominant, although the heavier forms are also elevated. In PLD muscle the same phenomenon occurs, but with a slower time course. In dystrophic pectoral muscle a similar rise in the L1 form of °ChE is first observed by day 4, with heavier forms also elevated in the mature muscle. Thus the alteration in the control of these two enzymes in dystrophic fast‐twitch muscles results in an accumulation of the light forms of AChE and °ChE.
EFFECTS OF EXCITATORY NEUROTRANSMITTER AMINO ACIDS ON SWELLING OF RAT BRAIN CORTICAL SLICES1
Authors: Chan Pak H. , Fishman Robert A. , Lee Jane L. , Candelise Livia 
Published: October 2006

Abstract— With the single rat brain cortical slice serving as an in vitro bio‐assay system, the effects of neurotransmitter amino acids (1 mm) on brain swelling, water, sodium and potassium content, inulin space, and lactate production were studied. The putative dicarboxylic amino acid neurotransmitters, l‐glutamic acid and l‐aspartic acids, greatly increased intracellular brain swelling with increased intracellular Na+, water content and lactate production, and decreased inulin space and intracellular K+. Equimolar GABA, taurine, glycine, the putative inhibitory neurotransmitter amino acids, and equimolar α‐amino‐isobutyric acid had no effect. Brain swelling and intracellular Na+/K+ ratios were greatly increased by l‐glutamate and l‐aspartate at a concentration of 10 mm. However, l‐aspartate at these concentrations greatly depleted the K+ content and lactate production as compared to l‐glutamate.Further studies indicated that only the structural analogs and isomers of the dicarboxylic amino acids possessing two acidic groups and an α‐amino group had a similar effect on the induction of brain swelling. Among the analogs of glutamic acid, dl‐homocysteic acid and kainic acid had a greater effect on brain swelling, as observed from the total adenosine 5′‐triphosphate (ATP) levels and the time‐course and dose‐response. A biphasic response in lactate production was induced by dl‐homocysteic acid and kainic acid, suggesting that these analogs had a neurotoxic effect on cellular metabolism at higher concentrations.
A MODEL OF HIGH AFFINITY CHOLINE TRANSPORT IN RAT CORTICAL SYNAPTOSOMES
Authors: Wheeler D. D. 
Published: October 2006

Abstract— Initial velocity of choline uptake by cortical synaptosomes from the Long‐Evans rat has been measured as a function of both choline and sodium concentration. These data were then fitted to the rate equation for each of several possible models which characterize the participation of sodium in the transport process, and the models giving best fit were identified. Although one cannot unequivocally distinguish between a model including a high affinity carrier component plus diffusion and one including both high affinity and low affinity carriers, the conclusions concerning the high affinity component are the same in both cases. The major conclusions from the model are as follows: (1) The carrier may first combine with either choline or sodium; if the first reaction is with sodium, then there is an obligatory reaction with a second sodium before choline can interact with the carrier. (2) Translocation may occur as either CS or CNa2S (C= carrier; S= choline; CS= carrier‐substrate complex). (3) The apparent maximal velocity (Va) is dependent on the sodium concentration. (4) K1, the choline concentration giving Va/2. is also dependent on the sodium concentration. K1 increases with [Na] from 0 to 38.41 mm; above 38.41 mm‐[Na]. K1 declines with [Na]. (5) There is a sigmoidal relationship between velocity of uptake and [Na]; however, uptake is not zero at [Na] = 0. (6) Jm. uptake at a given [choline] and infinite [Na]. is hyperbolically related to the choline concentration, but changes slowly over the range of 0.5–5.0 ± 10‐6m. (7) KNa, the sodium concentration giving a velocity equal to Jm/2, is related to the choline concentration by a quadratic equation, and was found to be greater than physiological [Na] at choline concentrations of 0.5, 0.6, or 1.0 ± 10‐6m. but less than physiological [Na] at choline concentrations of 2.0 or 5.0 ± 10‐6m.The best fit model for the high affinity uptake of choline is very similar to what has been found in previous studies for the high affinity uptake of glutamic acid and GABA, thus raising the question of whether or not all high affinity synaptosomal mechanisms may be variations of a common model.