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  • 1
    Electronic Resource
    Electronic Resource
    Characterization of Extracellular Histamine in the Striatum and Bed Nucleus of the Stria Terminalis of the Rat: An In Vivo Microdialysis Study (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 56 (1991), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The intracerebral microdialysis technique, coupled with a sensitive radioenzymatic assay, was employed to study histamine release in the striatum and in the bed nucleus of the stria terminalis (BNST) in conscious, freely moving rats. In these brain regions, extracellular histamine concentrations decreased by 20% when calcium was omitted from the perfusion solution. Extracellular histamine was insensitive to the addition of tetrodotoxin to the perfusion medium. In striatum, extracellular histamine concentrations declined in an apparent biexponential manner after the administration of α-fluoromethylhistidine, an inhibitor of histamine synthesis. The half-lives for the disappearance of histamine were 32 min and 7.7 h, indicating the presence of at least two histamine pools. Histidine loading resulted in a nearly twofold increase in histamine outflow in striatum. In the BNST, yohimbine increased the extracellular histamine content by 50%, suggesting that histamine release is subject to α2-adrenergic regulation in vivo. The extent to which histamine detected in cerebral microdialysis samples is of neurogenic origin remains to be established.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1991.tb02083.x
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  • 2
    Electronic Resource
    Electronic Resource
    A Simple, Sensitive, and Economic Assay for Choline and Acetylcholine Using HPLC, an Enzyme Reactor, and an Electrochemical Detector (1985)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 45 (1985), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: A simple, efficient, economic, and sensitive method is presented for the detection of choline and acetylcholine in neuronal tissue using HPLC, a postcolumn enzyme reactor with immobilized enzyme, and electrochemical detection. The method is based on a separation of choline and acetylcholine by cation exchange HPLC followed by passage of the effluent through a postcolumn reactor containing a mixture of acetylcholinesterase and choline oxidase; the latter enzyme converts choline to betaine and hydrogen peroxide, the former enzyme hydrolyzes acetylcholine to acetate and choline. The hydrogen peroxide produced is electrochemically detected. A simple and efficient preparation of neuronal tissue is described using an optional prepurification step on Sephadex G-10 columns, offering the possibility to detect choline and acetylcholine as well as catecholamines and their related metabolites in the same tissue sample. The sensitivity of the assay system is 250 fmol for choline and 500 fmol for acetylcholine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1985.tb07238.x
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  • 3
    Electronic Resource
    Electronic Resource
    Effects of Transient Forebrain Ischemia and Pargyline on Extracellular Concentrations of Dopamine, Serotonin, and Their Metabolites in the Rat Striatum as Determined by In Vivo Microdialysis (1990)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 54 (1990), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Striatal microdialysis was performed in rats subjected to 20 min of transient forebrain ischemia produced by occlusion of the carotid arteries during hemorrhagic hypotension. Extracellular changes of dopamine, serotonin, and their metabolites were monitored before, during, and after the ischemic insult at 10-min intervals by on-line HPLC analysis. During ischemia, extracellular dopamine increased dramatically (156 times baseline), as did 3-methoxytyramine (3-MT), whereas 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) decreased (15–25% of baseline). Upon reperfusion, dopamine was cleared from the extracellular fluid within 40 min and reached a stable level (70% of baseline). DOPAC and HVA increased (250–330%) transiently and reached their maximum 1 h following reperfusion, whereas 3-MT decreased to undetectable levels within 20 min. Although baseline levels of serotonin were not detectable, serotonin and 5-hydroxyindoleacetic acid showed a qualitatively similar temporal pattern to dopamine and its acid metabolites. Killing rats by cervical dislocation produced changes in extracellular dopamine, serotonin, and their metabolites that were almost identical to those seen during ischemia. Pargyline pretreatment 2 h before ischemia had marginal effects on the postischemic clearing of dopamine. The pargyline pretreatment, however, did increase the survival rate of rats subjected to ischemia, and this protective effect might be due to the pargyline-induced blockade of the postischemic monoamine oxidase-mediated increase in dopamine metabolism and the concurrent production of the potentially neurotoxic molecule, hydrogen peroxide.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1990.tb02322.x
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  • 4
    Electronic Resource
    Electronic Resource
    Effect of Ouabain Applied by Intrastriatal Microdialysis on the In Vivo Release of Dopamine, Acetylcholine, and Amino Acids in the Brain of Conscious Rats (1989)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 52 (1989), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: In the present study we have applied a brain microdialysis technique to investigate the effects of ouabain infusion on the release of dopamine, acetylcholine, and amino acids from striatal neurons in freely moving rats. Ouabain caused an increase in the dialysate levels of dopamine; its metabolite 3,4-dihydroxyphenylacetic acid (DOPAC); and the amino acids glutamate, aspartate, taurine, glycine, alanine, serine, asparagine, and threonine. The ouabain-induced increase in dopamine was dose dependent and explosive (100- fold at an infusion concentration of 1 mmol/L) and contrasted strongly with the small effect of the glycoside on the output of DOPAC. We investigated the nature of ouabain-induced transmitter release by determining its sensitivity to coinfusion with tetrodotoxin or the calcium antagonist Mg2+.In the case of dopamine two mechanisms of ouabain-induced release could be established. At lower infusion concentrations ouabain induced an exocytotic type of release whereas at higher concentrations the release was probably camer mediated. In the case of amino acids we noticed a calcium-independent release which was nerve impulse flow dependent in the case of glutamate and aspartate and impulse flow independent in the case of alanine, serine, glycine, threonine, and asparagine. Ouabain induced a decrease in the release of acetylcholine and glutamine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1989.tb02512.x
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  • 5
    Electronic Resource
    Electronic Resource
    Measurement of Acetylcholine Release in Freely Moving Rats by Means of Automated Intracerebral Dialysis (1987)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 48 (1987), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The present study demonstrates the feasibility of measuring acetylcholine in perfusion samples collected by means of in vivo brain dialysis in the striata of freely moving rats. The output of the dialysis device was directly connected to an automated sample valve of a HPLC-assay system that comprises a cation exchanger, a post-column enzyme reactor, and an electrochemical detector. The presence of an acetylcholinesterase inhibitor (neostigmine) in the perfusion fluid was required for the detection of acetylcholine in the perfusate. Increasing concentrations of neostigmine induced increasing amounts of acetylcholine. Continuous perfusion with a fixed concentration (2 μM) of neostigmineresultedingraduallyincreasingamounts of collected acetylcholine over time although a considerable variation between successive samples exists. The brain dialysis technique was further validated by studying the effect of various drugs. Systemically administered atropine increased the output of acetylcholine, whereas the addition of tetrodotoxin to the perfusion fluid resulted in a complete disappearance of the neurotransmitter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1987.tb05695.x
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  • 6
    Electronic Resource
    Electronic Resource
    Measurement of acetylcholine and choline in cerebrospinal fluid by high-performance liquid chromatography: failure to detect acetylcholine in normal human cerebrospinal fluid
    Amsterdam : Elsevier
    Journal of Chromatography B: Biomedical Sciences and Applications 529 (1990), S. 408-416 
    Details
    ISSN: 0378-4347
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/S0378-4347(00)83847-5
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  • 7
    Electronic Resource
    Electronic Resource
    Liquid chromatography with electrochemical detection for the determination of choline and acetylcholine in plasma and red blood cells - Failure to detect acetylcholine in blood of humans and mice
    Amsterdam : Elsevier
    Journal of Chromatography B: Biomedical Sciences and Applications 428 (1988), S. 1-8 
    Details
    ISSN: 0378-4347
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/S0378-4347(00)83884-0
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  • 8
    Electronic Resource
    Electronic Resource
    The significance of extracellular calcium for the release of dopamine, acetylcholine and amino acids in conscious rats, evaluated by brain microdialysis (1988)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 337 (1988), S. 373-378 
    Details
    ISSN: 1432-1912
    Keywords: Brain dialysis ; Striatum ; Dopamine ; Acetylcholine ; Verapamil ; Calcium ; Magnesium ; Amino acids ; Haloperidol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The influence of the calcium concentration of the perfusion fluid on the release of striatal dopamine recorded by brain dialysis was investigated. The release of dopamine appeared very sensitive to the calcium concentration of the Ringer. Next we studied whether three different methods known to antagonize the effects of calcium entry, were able to affect the release of dopamine. The conditions investigated were: the use of calcium-free Ringer, infusion of magnesium, and infusion of the calcium-antagonist verapamil. Calcium-antagonism was studied on the day of implantation of the cannula as well as on several days thereafter. It appeared that magnesium infusion was the most effective condition to antagonize the effects of calcium on the release of dopamine. Magnesium infusion was also most effective in preventing drug-evoked voltage-dependent dopamine release (induced by coadministration of haloperidol and GBR 12909). In addition magnesium infusion appeared a potent antagonist of acetylcholine release. In contrast, the dialysate content of aminoacids was not influenced by magnesium infusion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00169526
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  • 9
    Electronic Resource
    Electronic Resource
    Dopaminergic regulation of striatal cholinergic interneurons: an in vivo microdialysis study (1990)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 342 (1990), S. 523-527 
    Details
    ISSN: 1432-1912
    Keywords: Acetylcholine ; Choline ; Dopaminergic agents ; Microdialysis ; Rat ; Striatum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In vivo microdialysis was used to study the putative inhibitory effects of dopamine on cholinergic interneurons in the striatum of conscious rats. The dopamine receptor agonists apomorphine (0.3 and 3 mg/kg, s.c.) and (±)N-0437 (1.4 mg/kg, s.c.) decreased interstitial concentrations of acetylcholine while increasing those of choline. In contrast, the dopamine receptor antagonists haloperidol (0.1 and 1 mg/kg, i.p.) and (±)sulpiride (20 mg/kg, i.p.) enhanced striatal acetylcholine output but had little effect on choline. Previously, a lack of effect of these drugs on striatal acetylcholine was reported. The main methodological difference between these studies was that the calcium concentration of the microdialysis perfusion solution was 3.4 mM in the former study versus 1.2 mM in the present experiments. The results of this study reemphasize the importance of the calcium concentration in determining the effects of drugs on central neurotransmitter release, and confirm a role of dopamine in the regulation of striatal cholinergic interneurons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00169040
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  • 10
    Electronic Resource
    Electronic Resource
    The use of tetrodotoxin for the characterization of drug-enhanced dopamine release in conscious rats studied by brain dialysis (1987)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 336 (1987), S. 502-507 
    Details
    ISSN: 1432-1912
    Keywords: Brain dialysis ; Striatum ; Nucleus accumbens ; Dopamine ; Amphetamine ; Tetrodotoxin ; Morphine ; 1-methyl-4-phenylpyridinium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effect of TTX (infused during brain dialysis of the striatum and nucleus accumbens) on the in vivo release of dopamine, 3,4-dihydroxyphenylacetic acid and homovanillic acid, was investigated. In addition it was studied whether the increase in the release of dopamine, induced by various pharmacological treatments, was sensitive to TTX infusion. The following drugs were studied: haloperidol, amphetamine, haloperidol co-administered with GBR 12909, morphine and MPP+. Dialysis was carried out in the striatum, except for morphine, which was studied in the nucleus accumbens. The infusion of TTX revealed three different types of pharmacologically enhanced dopamine release in conscious rats. First, action potential dependent dopamine release (exocytosis), which was observed in untreated animals as well as in animals treated with haloperidol, haloperidol + GBR 12909, and morphine. Second, action potential independent release (carrier-mediated) was established in the case of amphetamine. Third, action potential independent DA release, probably caused by neurotoxic reactions was observed during MPP+ infusion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00169306
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