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  • 1
    Electronic Resource
    Electronic Resource
    Dopamine Receptor Blockade Inhibits the Amphetamine-Induced Release of Diadenosine Polyphosphates, Diadenosine Tetraphosphate and Diadenosine Pentaphosphate, from Neostriatum of the Conscious Rat (1995)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 64 (1995), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The diadenosine polyphosphates diadenosine tetraphosphate (Ap4A) and diadenosine pentaphosphate (Ap5A) are costored with ATP and released in a calcium-dependent manner from neural preparations in vitro. By means of a push-pull perfusion system, samples from conscious rat were collected from the caudate putamen area, and nucleotide compounds were analyzed by HPLC. The adenine dinucleotides were not detectable before systemic amphetamine injection. The maximal levels were reached 20 min after injection, independently of the dose. The EC50 values for amphetamine-induced release of dinucleotides were 2.04 ± 0.15 and 2.43 ± 0.36 mg/kg for Ap4A and Ap5A, respectively. Amphetamine doses higher than 5 mg/kg did not increase the dinucleotide release, the maximal values being 12.9 ± 0.9 and 11.5 ± 0.9 pmol/fraction for Ap4A and Ap5A, respectively, which corresponds with 64.5 and 57.5 nM in the samples. Adenosine and AMP were present in push-pull samples from rat brain under basal conditions. Their levels were 15 pmol/fraction (75 nM) and 50 pmol/fraction (250 nM) for adenosine and AMP, respectively. A significant increase was obtained for both compounds after amphetamine injection. The adenosine increase reached 45 pmol/sample (225 nM), which was 200% of the basal value 20 min after the stimulant administration. The increase at other times was not significant. The AMP levels increased significantly from 10 to 50 min. The maximal level was reached 20 min after amphetamine injection, with 150 pmol/fraction (750 nM), which represents a 200% increase with respect to the basal level. The adenine dinucleotide release was blocked by the dopamine receptor antagonist haloperidol, which returned the levels to the control basal values. It is suggested that dopamine, released in a nonexocytotic way by the action of amphetamine, induces the release of the dinucleotides Ap4A and Ap5A in the neostriatum area through dopaminergic receptors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.1995.64020670.x
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  • 2
    Electronic Resource
    Electronic Resource
    Fixed Versus Removable Microdialysis Probes for In Vivo Neurochemical Analysis: Implications for Behavioral Studies (1994)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 63 (1994), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The levels of several neurochemicals, i.e., uric acid (UA), dopamine (DA), dihydroxyphenylacetic acid, and 5-hydroxyindoleacetic acid, collected daily from the rat striatum with either fixed or removable microdialysis probes for 7 days after surgery were compared. The implantation of the fixed cannula was followed by a 10-fold increase in the UA content in the dialysates collected from the first day after surgery onward and by a steady decrease in dihydroxyphenylacetic acid levels, whereas those of DA remained fairly stable. With the removable cannula system, only a smaller, transient increase in UA during the first 3 days after surgery was observed, with no change in DA or monoamine metabolites. The glial reaction around the cannula tracks was assessed by both quantitative histological techniques and measuring the glutamine levels in the dialysates collected at the time of surgery and 7 days later. Both the glial cell number and nuclear size, as well as the glutamine outflow, were considerably larger in the animals implanted with the fixed probes. It is, therefore, likely that the UA levels in the dialysate reflect the glial reaction to the probe. The suitability of the removable probe system for behavioral experiments involving repeated microdialysis sampling was illustrated in an experiment showing that the DA release in the nucleus accumbens of male rats assessed daily at postsurgery days 5–10 was virtually identical in three alternating sessions of sexual behavior as was the smaller release of this neurotransmitter detected during intervening nonsexual social interactions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.1994.63041407.x
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  • 3
    Electronic Resource
    Electronic Resource
    Structural Characterization by Affinity Cross-Linking of Glucagon-Like Peptide-1(7–36)Amide Receptor in Rat Brain (1995)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 64 (1995), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Specific binding of glucagon-like peptide (GLP)-1(7–36)amide was detected in several rat brain areas, with the highest values being found in hypothalamic nuclei and the nucleus of the solitary tract. In hypothalamus and brainstem homogenate binding of 125I-GLP-1(7–36)amide was time, temperature, and protein content dependent and was inhibited by unlabeled proglucagon-derived peptides. The rank order of potency was GLP-1(7–36)amide ≫ GLP-1(1–36)amide 〉 GLP-1(1–37) ≅ GLP-2 〉 glucagon. Scatchard analysis of the steady-state binding data was consistent with the presence of both high- and low-affinity binding sites in hypothalamus and brainstem. Brain 125I-GLP-1(7–36)amide-binding protein complexes were covalently cross-linked using disuccinimidyl suberate and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. A single radiolabeled band of Mr 56,000 identified in both hypothalamus and brainstem homogenates was unaffected by reducing agents. An excess of unlabeled GLP-1(7–36)amide abolished the band labeling, whereas glucagon had no effect. Other unlabeled GLPs inhibited Mr 56,000 complex labeling with the following order of potency: GLP-1(1–36)amide 〉 GLP-1(1–37) 〉 GLP-2. The binding of 125I-GLP-1(7–36)amide and the intensity of the cross-linked band were similarly inhibited in a dose-response manner by increasing concentrations of unlabeled GLP-1(7–36)amide. Covalent Mr 56,000 125I-GLP-1(7–36)amide-binding protein complexes solubilized by Triton X-100 were adsorbed onto wheat germ agglutinin. Our results suggest that the GLP-1(7–36)amide receptor in rat brain is a glycoprotein with a single binding subunit that has a greater molecular weight but binding features and ligand specificity similar to those of its peripheral tissue counterparts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.1995.64010299.x
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  • 4
    Electronic Resource
    Electronic Resource
    Effects of Apomorphine and L-Methionine Sulphoximine on the Release of Excitatory Amino Acid Neurotransmitters and Glutamine in the Striatum of the Conscious Rat (1994)
    Oxford, UK : Blackwell Publishing Ltd
    European journal of neuroscience 6 (1994), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The effects of apomorphine, a D1-, D2-dopamine receptor agonist, on the extracellular concentrations of excitatory amino acids, glutamic and aspartic acids, and on that of their precursor, glutamine, were investigated using an intracerebral perfusion system. Apomorphine produced a concentration-related rise in glutamic acid concentration in cerebral perfusates (P 〈 0.01) whereas only the highest concentration of apomorphine (3 × 10-3μg/μl) increased the concentration of aspartic acid (P 〈 0.05). These effects were seen in the sample taken at the same time as the apomorphine injection. The rise in glutamine concentration (P 〈 0.01) produced by apomorphine continued for 10 min beyond perfusion with apomorphine. These effects were attenuated by previous injections of a D1-, D2-dopamine receptor blocker. To investigate further the release of glutamine, the glutamine synthetase inhibitor L-methionine sulphoximine (MSO) was injected intracerebrally before apomorphine perfusion. After MSO pre-injection, the extracellular concentration of glutamine decreased (P 〈 0.01) to near zero concentrations. In MSO-treated animals, apomorphine did not induce the release of glutamic acid, aspartic acid or glutamine. These results indicate a role for dopamine in the release of excitatory amino acids and glutamine in the neostriatum of the rat. A possible volumetric interaction between dopamine and glutamic acid as well as the hypothesis of a striato-pallido-thalamo-cortico-striatal feedback loop are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-9568.1994.tb00271.x
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  • 5
    Electronic Resource
    Electronic Resource
    Dopamine-Glutamate-GABA Interactions and Ageing: Studies in the Striatum of the Conscious Rat (1995)
    Oxford, UK : Blackwell Publishing Ltd
    European journal of neuroscience 7 (1995), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The effects of apomorphine, a D1–D2 dopamine receptor agonist, on the extracellular concentrations of glutamate and GABA were investigated in the striatum of young, middle-aged and aged rats. In vivo intracerebral perfusions were undertaken in the conscious rat using a concentric push-pull cannula system. Amino acid concentrations in samples were determined by HPLC with fluorometric detection. Apomorphine produced a concentration-related rise in striatal glutamate and GABA concentrations in young rats. Maximal increases were obtained at 20 μM apomorphine, and concentrations reached 184 and 191% of the basal value for glutamate and GABA respectively. Apomorphine failed to produce similar increases in glutamate concentration in middle-aged and aged rats. Apomorphine, at 10 μM, also failed to produce an increase in GABA concentration in the aged rat. However, at 20 μM apomorphine produced increases in GABA concentration in middle-aged and aged rats similar to those produced in young rats. These data are indicative of a change in threshold for GABA release induced by dopamine receptor stimulation in the aged rat. These results indicate that an interaction among dopamine, glutamate and GABA exists in the striatum of the rat, and that this type of interaction deteriorates with age.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-9568.1995.tb00640.x
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  • 6
    Electronic Resource
    Electronic Resource
    Endogenous Glutamate Increases Extracellular Concentrations of Dopamine, GABA, and Taurine Through NMDA and AMPA/Kainate Receptors in Striatum of the Freely Moving Rat: A Microdialysis Study (1997)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 69 (1997), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Interactions between glutamate (Glu), dopamine (DA), GABA, and taurine (Tau) were investigated in striatum of the freely moving rat by using microdialysis. Intrastriatal infusions of the selective Glu uptake inhibitor l-trans-pyrrolidine-3,4-dicarboxylic acid (PDC) were used to increase the endogenous extracellular [Glu]. Correlations between extracellular [Glu] and extracellular [DA], [GABA], and [Tau], and the effects of a selective blockade of ionotropic Glu receptors, were studied. PDC (1, 2, and 4 mM) produced a dose-related increase in extracellular [Glu]. At the highest dose of PDC, [Glu] increased from 1.55 ± 0.35 to 6.11 ± 0.88 µM. PDC also increased extracellular [DA], [GABA], and [Tau]. The increasing [Glu] was correlated significantly with increasing [DA], [GABA], and [Tau]. PDC also decreased extracellular concentrations of DA metabolites 3,4-dihydroxyphenylacetic acid (DOPAC) and 4-hydroxy-3-methoxyphenylacetic acid (HVA). Perfusion with the NMDA-receptor antagonist 3-[(R)-2-carboxypiperazin-4-yl]-propyl-1-phosphonic acid (1 mM) or the AMPA/kainate-receptor antagonist 6,7-dinitroquinoxaline-2,3-dione (DNQX) (1 mM) attenuated the increases produced by PDC (4 mM) on [DA], [GABA], and [Tau], and decreases in [DOPAC] and [HVA]. DNQX also attenuated the increases in [Glu] induced by PDC. These data show that endogenous Glu plays a role in modulating the extracellular concentrations of DA, GABA, and Tau in striatum of the freely moving rat.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.1997.69041476.x
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  • 7
    Electronic Resource
    Electronic Resource
    The Prevalence of Peptic Ulcer not Related to Helicobacter pylori or Non-Steroidal Anti-Inflammatory Drug Use is Negligible in Southern Europe (2004)
    Oxford, UK : Blackwell Science Ltd
    Helicobacter 9 (2004), S. 0 
    Details
    ISSN: 1523-5378
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background and Aim.  Helicobacter pylori is the major cause of peptic ulcer disease, but the proportion of H. pylori-negative peptic ulcers seems to be increasing in developed countries. We investigated the frequency of H. pylori-negative peptic ulcer without intake of nonsteroidal anti-inflammatory drugs (NSAIDs) in a Mediterranean European country.Materials and Methods.  We prospectively collected consecutive patients with an endoscopically verified active peptic ulcer over 6 months from different areas of Spain. Helicobacter pylori infection was assessed by rapid urease test and histologic examination (corpus and antral biopsies). A 13C-urea breath test was performed if H. pylori was not detected with the invasive test. Patients were considered H. pylori-negative if all three tests were negative. NSAID use was determined by structured data collection.Results.  Of 754 consecutive peptic ulcer patients, 16 (2.1%) were H. pylori-negative and had not used NSAIDs before the diagnosis. Of the 472 patients who had duodenal ulcers, 95.7% (n = 452) were H. pylori-positive and only 1.69% (n = 8) were negative for both H. pylori infection and NSAID use; 193 patients had benign gastric ulcers and 87% (n = 168) of them were infected by H. pylori (p 〈 .001 vs. duodenal ulcers). NSAID intake was more frequent in gastric ulcer patients (52.8%) than in duodenal ulcer patients (25.4%; p 〈 .001). Consequently, the frequency of H. pylori-negative gastric ulcer in patients not using NSAID was 4.1% (n = 8).Conclusion.  Peptic ulcer disease is still highly associated with H. pylori infection in southern Europe, and only 1.6% of all duodenal ulcers and 4.1% of all gastric ulcers were not associated with either H. pylori infection or NSAID use.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1083-4389.2004.00219.x
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  • 8
    Electronic Resource
    Electronic Resource
    Circadian rhythms of dopamine, glutamate and GABA in the striatum and nucleus accumbens of the awake rat: modulation by light (2004)
    Oxford, UK : Munksgaard International Publishers
    Journal of pineal research 36 (2004), S. 0 
    Details
    ISSN: 1600-079X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract:  Using microdialysis, we investigated the circadian rhythms of the extracellular concentrations of dopamine, glutamate and γ-aminobutyric acid (GABA) in the striatum and nucleus accumbens of the awake rat. Wistar rats were maintained in a 12 hr dark:12 hr light (12:12) cycle for 2 wk before the experiment began. The neurotransmitter levels were measured every 30 min for 30 hr in control (maintaining the 12:12 cycle) or in experimental conditions under a 24-h light period (continuous light) or under a 24-h dark interval (continuous dark). The dopamine metabolites, DOPAC and HVA, and the main serotonin metabolite, 5-HIAA, were measured along with arginine and glutamine under all conditions. In 12:12 conditions, a circadian rhythm of dopamine, glutamate and GABA was found in both the striatum and nucleus accumbens. Again under 12:12 conditions, DOPAC, HVA, 5-HIAA, and arginine, but not glutamine, fluctuated in a circadian rhythm. In the striatum under constant light conditions, there was a circadian rhythm of dopamine, glutamate, GABA, DOPAC and HVA, but not 5-HIAA. By contrast, when the rats were kept under continuous dark, dopamine and its metabolites, DOPAC and HVA (but not glutamate and GABA), did not fluctuate in a circadian rhythm. In the nucleus accumbens, under both constant light or dark conditions, no changes were found in the circadian rhythm in any of the neurotransmitters and metabolites studied. These findings show that in the striatum, dopamine but not glutamate and GABA, seem to be influenced by light. In the nucleus accumbens, however, the three neurotransmitters had a circadian rhythm, which was independent of light.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1600-079X.2003.00114.x
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  • 9
    Electronic Resource
    Electronic Resource
    Perfusion of melatonin into the prefrontal cortex disrupts the circadian rhythm of acetylcholine but not of locomotor activity (2003)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of pineal research 35 (2003), S. 0 
    Details
    ISSN: 1600-079X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Extracellular concentrations of acetylcholine (ACh) in the prefrontal cortex displayed a circadian rhythm, with a maximum increase in the dark phase of the light:dark cycle. The increase in ACh related well to the circadian rhythm of the same rats in which a maximal increase of locomotor activity in the dark phase also was observed. Local perfusion of melatonin (200–500 μm), in a dose-dependent manner, disrupted the ACh rhythm in the prefrontal cortex but did not affect the circadian rhythm of locomotor activity. It is suggested that the change in the cholinergic transmission during a circadian period in the prefrontal cortex may be under the control of the biological clock through the action of melatonin; however, the prefrontal cortical ACh cycle seems not to be related to the regulation of locomotor activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1600-079X.2003.00088.x
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  • 10
    Electronic Resource
    Electronic Resource
    Manometric Comprobation of Esophagogastric Junction Competence after Nissen Fundoplication and Its Relation to the Length of Fundic Wrap (2000)
    Springer
    World journal of surgery 24 (2000), S. 870-873 
    Details
    ISSN: 1432-2323
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. We present 98 patients operated on by two techniques of 360-degree fundoplication due to gastroesopagheal reflux disease and divided in two groups: Group I comprised those who were given a conventional valve 5 cm in length, and group II underwent a short fundoplication that did not surpass 1.5 cm. All were subjected to preoperative esophageal manometry, with determination of the pressure and length of the lower esophageal sphincter (LES) and the motor behavior of the esophageal body. The postoperative manometric results are analyzed, checking that after fundoplication there was a significant increase in tone and length of the LES (p 〈 0.00005); there were no differences between the two groups (p= 0.9920 and p= 0.2160, respectively). The motor function of the esophageal body did not change after surgery. We conclude that even the smallest length of the fundic wrap does not cause a reduction in the pressure and length of the manometric LES; that is, the antireflux effectiveness, measured by manometry, did not depend on the anterior length of the valvuloplasty.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002680010139
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