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PubMed1982

Immunohistochemical evidence of indolamine neurons in monkey spinal cord.

In this study, we have identified over 150 cells in the adult macaque spinal cord that are immunoreactive when stained with an antibody to 5-HT by means of the PAP method. The staining was blocked by preabsorption of the primary antibody by the 5-HT-BSA conjugate (used to generate the antibody) and by 5-HT, while BSA, dopamine, norepinephrine, 5-methoxytryptamine and tryptamine preabsorption did not block staining. In addition, the Falck-Hillarp histofluorescence technique was applied to the lumbosacral cord from one of the three monkeys studied; results confirm the presence of cells with yellow fluorescence and rapid fading to brown characteristic for serotoninergic cells. The neuronal identity of these immunoreactive cells is based on light and electron microscopic morphology and the presence of synaptic terminals in contact with labeled somata and dendrites. Most of these neurons were small (10-25 micrometers) and located ventral to the central canal in lamina X. Some processes of the cells extended into the intermediate gray and the ventromedial area of the ventral horn; other processes wrapped around large blood vessels in lamina X or around the wall of the central canal. Cells were most frequent in the cervical cord (approximately 6-7/mm length of cord) and less frequent in the thoracic (1.5/mm), lumbar (3/mm), and sacral (2/mm) cord. A few cells were also found in the marginal and gelatinosa regions of the dorsal horn of the sacral cord. Examination of sections from the medulla-spinal cord junction (obex level) indicates that the spinal cells may be an extension of cell groups located near the raphe obscurus in the gray region around the IVth ventricle. The indolamine spinal cells may act as interneurons in spinal circuits, control spinal blood flow through vessel innervation, or play a role in CSF composition through central canal innervation.

Animals↗
PubMed1990

Electron microscopic analysis of S-antigen- and serotonin-immunoreactive neural and sensory elements in the photosensory pineal organ of the salmon.

Photoreceptor cells in the pineal complex of poikilothermic vertebrates are regarded as homologous with the neuroendocrine pinealocytes in the mammalian pineal organ. They possess an indolamine metabolism, and they contain a number of substances that are immunochemically similar to photo-transduction-related proteins otherwise found in photoreceptors of the lateral eye retina. Using correlative light and electron microscopic pre-embedding immunocytochemistry, we have identified photosensory and neural elements that are immunoreactive with specific antisera against serotonin (5-hydroxy-tryptamine) and the 48 kDa soluble protein S-antigen (arrestin). One type of serotonin-immunoreactive (5HTir) photoreceptor cell was identified. This was characterized by a short basal pole, into which an immunonegative (post-synaptic?) element protruded. Two types of S-antigen-immunoreactive (SAir) photoreceptor cells were observed, one characterized by a short basal pole, similar to that of the 5HTir photoreceptors and the other characterized by a long, extensively branching basal pole. In addition, two types of neurons bearing no morphological specializations typical of photoreceptor cells were SAir: bipolar neurons and multipolar neurons. These were often situated dorsally in the pineal organ. The results indicate an emergence of multiple lines of photoreceptor-derived "pinealocytes" either early in phylogeny, or independently in different taxa. The results are discussed in relation to current theories of pineal evolution.

Animals↗
PubMed1977

Initial clinical trial based on biochemical methodology of zimelidine (a serotonin uptake inhibitor) in depressed patients.

The bicyclic compound Z-1-(4-bromophenyl)-1-(3-pyridyl)-3-dimethylaminopropen (zimelidine) has a pronounced inhibitory effect on neuronal 5-hydroxytryptamine (5-HT) uptake in animals. Zimelidine was given to 6 depressed patients in doses ranging between 25 and 150 mg twice daily for about 3 wk. To get an objective assessment of its pharmacologic effects, the following variables were monitored: (1) plasma levels of parent compound and its desmethylated metabolite; (2) the 5-HT and norepinephrine (NE) uptake inhibiting activity in vitro of plasma drawn from the patients; and (3) the concentrations of the main metabolites of serotonin (5-HT), tryptamine, NE, and dopamine in cerebrospinal fluid (CSF), i.e., 5-hydroxyindoleacetic acid (5-HIAA), indoleacetic acid (IAA), 4-hydroxy-3-methoxyphenylglycol (HMPG), and homovanillic acid (HVA), respectively. Plasma from the patients markedly inhibited 5-HT uptake compared to NE uptake. The inhibitory effect of 5-HT uptake and the plasma concentration of the desmethylated metabolite correlated significantly. The 5-HIAA levels in CSF decreased markedly in 4 patients while the IAA levels increased. The levels of HMPG also decreased significantly, but less so than the 5-HIAA levels. The effects on HVA were inconsistent. Zimelidine appears to be a selective inhibitor of 5-HT uptake in central monoamine neurons and is therefore an interesting pharmacologic tool in future central nervous system (CNS) research.

Animals↗
PubMed2005

Separation and determination of L-tryptophan and its metabolites by capillary micellar electrokinetic chromatography with amperometric detection.

A high-performance method of capillary micellar electrokinetic chromatography (CMEKC) with amperometric detection (AD), using a newly designed pre-aligned electrochemical cell, has been developed for the separation and determination of L-tryptophan (Trp) and its eight metabolites including 3-hydroxy-L-kynurenine (3-HK), 5-hydroxy-L-tryptophan (5-HTP), L-kynurenine (KN), 5-hydroxyindole-3-acetic acid (5-HIAA), xanthurenic acid (XA), indole-3-pyruvic acid (IPA), 5-hydroxytryptamine (5-HT), and tryptamine (Tryp). A carbon disk electrode was used as the working electrode and the optimal detection potential was 0.85 V (versus Ag/AgCl). At 24 kV of applied voltage, the nine compounds were completely separated, within 23 min, in a 10 mol/L Na(2)HPO(4)-NaOH buffer (pH 11.0) containing 40 mmol/L sodium dodecyl sulfate (SDS) and 3% methanol (v/v). A good linear relationship was obtained for all analytes in this paper and the detection limits of 3-HK, 5-HTP, KN, Trp, 5-HIAA, XA, IPA, 5-HT, and Tryp were 7.42, 5.18, 34.6, 3.99, 15.1, 12.7, 260, 6.72, and 8.01 nmol/L, respectively. This method has been applied to analyze the metabolism of Trp in rabbit urine.

Animals↗
PubMed2005

Discontinuous electrolyte systems for improved detection of biologically active amines and acids by capillary electrophoresis with laser-induced native fluorescence detection.

On-line concentration and separation of biologically active amines and acids by capillary electrophoresis (CE) in conjunction with laser-induced fluorescence using an Nd:YAG laser at 266 nm under discontinuous conditions is presented. The suitable conditions for simultaneous analysis of amines and acids were: samples were prepared in a solution (pH* 3.1) consisting of 10 mM citric acid, 89% acetonitrile (ACN), and water; a capillary was filled with 1.5 M Tris-borate (TB) buffer (pH 10.0); and the anodic vial contained PTG10 buffer (pH* 9.0) that consists of 50 mM propanoic acid, Tris, 10% glycerol, and water. After injecting a large-volume sample, amines and acids were separately stacked at the front (cathodic side) and back (anodic side) of the acidic sample zone, mainly because of changes in their electrophoretic mobilities as a result of changes in pH, viscosity, and electric field when high voltage was applied. When the sample was injected at 15 kV for 360 s, the concentration limits of detection (LODs) for 5-hydroxytryptamine (5-HT) and 5-hydroxyindole-3-acetic acid (5-HIAA) were 0.27 and 0.31 nM, respectively, which are about 400- and 800-fold sensitivity improvements when compared to those injected at 1 kV for 10 s. For the analysis of amines, samples were prepared in 100 mM citric acid (pH* 1.8) containing 89% ACN and both the capillary and anodic vial were filled with 400 mM PTG20 (propanoic acid, Tris, 20% glycerol, and water) at pH* 4.5. Using a large injection volume (15 kV for 360 s), we achieved concentration LODs of 17 pM and 0.3 nM for tryptamine and epinephrine, which are about 5200- and 14,000-fold sensitivity improvements, respectively, in comparison with those injected at 1 kV for 10 s. The features of simplicity (no sample pretreatment), rapidity (12 min), and sensitivity for identification of amines and acids of interest in urine samples show diagnostic potential of the two approaches developed in this study.

Acids↗
PubMed2005

Silica nanoparticles for separation of biologically active amines by capillary electrophoresis with laser-induced native fluorescence detection.

This paper describes the analysis of biologically active amines by capillary electrophoresis (CE) in conjunction with laser-induced native fluorescence detection. In order to simultaneously analyze amines and acids as well as to achieve high sensitivity, 10 mM formic acid solutions (pH < 4.0) containing silica nanoparticles (SiNPs) were chosen as the background electrolytes. With increasing SiNP concentration, the migration times for seven analytes decrease as a result of increase in electroosmotic flow (EOF) and decrease in their electrophoretic mobilities against EOF. A small EOF generated at pH 3.0 reveals adsorption of SiNPs on the deactivated capillary wall. The decreases in electrophoretic mobilities with increasing SiNP concentration up to 0.3x indicate the interactions between the analytes and the SiNPs. Having a great sensitivity (the limits of detection at a signal-to-noise ratio (S/N) = 3 of 0.09 nM for tryptamine (TA)), high efficiency, and excellent reproducibility (less than 2.4% of the migration times), this developed method has been applied to the analysis of urinal samples with the concentrations of 0.50 +/- 0.02 microM, 0.49 +/- 0.04 microM, and 74 +/- 2 microM for TA, 5-hydroxytryptamine, and tryptophan, respectively. The successful examples demonstrated in this study open up a possibility of using functional nanoparticles for the separation of different analytes by CE.

Body Fluids↗
PubMed2006

Capillary electrophoresis determination of biogenic amines by field-amplified sample stacking and in-capillary derivatization.

A sensitive CE method for determining biogenic amines in wines based on in-capillary derivatization with 1,2-naphthoquinone-4-sulfonate is presented. In this method, reagent and buffer solutions are introduced hydrodynamically into the capillary whereas the sample is injected electrokinetically, thus, allowing a selective preconcentration of the analytes by field-amplified sample stacking. Amines are labeled inside the capillary using a zone-passing derivatization approach in mixed tandem mode. The most relevant variables influencing on the derivatization and separation as well as significant interactions have been evaluated using experimental design. Multi-criteria decision making is utilized for the simultaneous optimization of interacting variables through overall desirability response surfaces. The validation of the method has proven an excellent separation performance and accuracy for the determination of biogenic amines such as histamine, tryptamine, phenylethylamine, tyramine, agmatine, ethanolamine, serotonin, cadaverine, and putrescine in red wines. Detection limits range from 0.02 mg/L for ethanolamine to 0.91 mg/L for serotonin. The RSDs for migration time and peak area are around 1.2 and 6.2%, respectively. Red wines from different Spanish regions have been analyzed using the proposed method.

Biogenic Amines↗
PubMed2002

Genotoxicity of naturally occurring indole compounds: correlation between covalent DNA binding and other genotoxicity tests.

3-Methylindole (3MI), melatonin (Mel), serotonin (Ser), and tryptamine (Tryp) were evaluated in vitro for their potential to induce DNA adducts, DNA strand breaks, chromosomal aberrations (Abs), inhibition of DNA synthesis, and mutations. All compounds produced DNA adducts in calf thymus DNA in the presence of rat liver S9. In cultured rat hepatocytes, all produced DNA adducts but none induced DNA strand breaks. In Chinese hamster ovary cells, 3MI and Mel produced DNA adducts, Abs, and inhibition of DNA synthesis with and without S9, except that Mel without S9 did not form adducts. Ser formed DNA adducts, was an equivocal Abs inducer, and suppressed DNA synthesis. Tryp induced neither adducts nor Abs, but did suppress DNA synthesis with S9. Ser and Tryp were less cytotoxic than 3MI and Mel. Mel, Ser, and Tryp failed to induce mutations in Salmonella and E. coli strains with or without S9. 3MI and Mel produced DNA adducts but not mutations in Salmonella TA100 with S9. 3MI and its metabolite indole 3-carbinol also did not induce mutations in a shuttle vector system in human cells. The lack of correlation between DNA adducts and other genotoxicity endpoints for these indole compounds may be due to the higher sensitivity of the (32)P-postlabeling adduct assay or it may indicate that the indole-DNA adducts per se are not mutagenic and are not able to induce strand breaks or alkali-labile lesions. The indole-induced Abs may result from cytotoxicity and suppression of DNA synthesis with minimal if any contribution from DNA adducts.

Animals↗
PubMed1987

Dopamine and noradrenaline content in fish retina: modulation by serotonin.

The presence of noradrenaline (NA) and the possible interaction of serotonin (5-HT) with dopaminergic and noradrenergic neuronal elements was studied in the retina of the teleost Eugerres plumieri. By means of a histofluorescent technique, paired amacrine cells can be visualized after intravitreal injection of NA or 5,6-dihydroxytriptamine, suggesting their probable catecholaminergic and indoleaminergic nature. With a high-performance liquid chromatographic (HPLC) method and after pargyline treatment of the animal, 6.86 ng/mg protein of dopamine (DA) was detected, while NA content was 0.50 ng/mg protein. The NA levels of the retina increased, whereas the DA levels decreased in a significant manner after in vivo treatment with 5-HT. 5-methoxy-N,N-dimethyltryptamine, a 5-HT agonist, was able to mimic this effect partially, while the agonists tryptamine and quipazine did not affect the levels of DA and NA. The antagonists methysergide, metergoline, and cyproheptadine significantly blocked the 5-HT-induced NA increase, whereas only the first two antagonists were effective in inhibiting the 5-HT-induced DA decrease. The 5-HT modulation of NA and DA is apparently receptor mediated and is not due to a hetero-exchange, since imipramine was not able to block the 5-HT effect. These findings support the suggested interaction between serotoninergic and dopaminergic cells [Negishi et al: J Neurosci Res 5:621-635, 1980; Neurosci Lett 25:1-5, 1981]. Furthermore, they demonstrate the possible modulation which 5-HT exerts on the endogenous levels of NA.

Animals↗
PubMed1995

Protein kinase C modulates exogenous acetylcholine current in Xenopus oocytes.

The modulation of acetylcholine-activated current (IACh) by protein kinase C (PKC) was studied in Xenopus laevis oocytes microinjected with either mRNA extracted from C2C12 myotubes (C2C12 mRNA) or RNAs encoding murine alpha beta gamma delta subunits of the nicotinic ACh receptor (nAChR). Voltage-clamped oocytes were treated for 90 sec with 12-O-tetradecanoylphorbol-13-acetate (TPA, 300 nM), a potent PKC activator. Transient increase in the amplitude and acceleration in the decay of IACh were invariably observed within minutes of TPA application, and were independent of extracellular Ca2+ concentration. Both parameters recovered to control within 20-30 min; then a slight depression of IACh developed. By this time, an initial PKC down regulation was observed. At the peak of TPA-induced potentiation, dose-response relations suggested an increased binding affinity of nAChR for the neurotransmitter. 4 alpha-phorbol 12,13-didecanoate (300 nM), a biologically inactive analogue of TPA, did not affect IACh, while staurosporine (5-10 microM), a potent inhibitor of PKC activity, suppressed the action of TPA on IACh. In oocytes co-injected with C2C12 mRNA and with rat brain mRNA, IACh was potentiated by 5-hydroxy-tryptamine (10 microM), whose receptors are coupled to phosphoinositide hydrolysis. The nAChR-channel activity in cell-attached patches increased when TPA was applied to the oocytes. In 50% of the oocytes examined, a sustained depression of the single channel activity followed. We conclude that in Xenopus oocytes an endogenous PKC system regulates the function of embryonic-type muscle nAChRs.

Acetylcholine↗
PubMed1976

Quantum chemical studies on drug action V: Involvement of structure-activity, quantum chemical, and hydrophobicity factors in thrombocyte uptake of 5-hydroxytryptamine.

Inhibition of the uptake of 5-hydroxytryptamine (serotonin) in the thrombocyte by various tryptamine derivatives was investigated. The activity depended on the nature and position of the substituent. This activity was correlated with the total orbital energy and hydrophobicity factors. Other quantum parameters, such as the highest occupied molecular orbital energy and the lowest empty molecular orbital energy, failed to correlate. The possible involvement of two receptor sites that are sterically and electronically dissimilar is postulated because compounds fell into two distinct groups. The hydrophobicity factor was important in only one group of compounds, while the electronic factor was important in both.

Animals↗
PubMed1979

Monoamine oxidase inhibition by beta-carbolines: a quantum chemical approach.

Monoamine oxidase inhibition by beta-carboline derivatives is related to the energy change, delta E, arising from complex formation between the inhibitor and the enzyme. The energy change was expressed in terms of electronic indexes, which were estimated for a set of aromatic beta-carbolines. The electronic indexes were correlated to the experimental activity indexes by a simplified quantum chemical perturbational treatment with a multiple regression procedure. A characteristic structure for the inhibitor-enzyme complex was derived from the correlation. The molecules are linked by two kinds of bond. One involves the lone pyridine nitrogen pair of beta-carbolines; the other is due to a pi-electronic interaction between the inhibitor indole fragment and a suitable area of the enzyme. Such a model explains the competitive inhibition by beta-carbolines compared to tryptamine and other aromatic amines that are monoamine oxidase substrates.

Carbolines↗
PubMedDate not supplied

Development of an efficient system for the separation of indole alkaloids by high performance liquid chromatography and its applications.

An efficient system for the analysis of indole alkaloids by HPLC on a reversed-phase column using an ion pair technique is described. The optimised chromatographic conditions allowed the successful separation of 22 standard monoterpenoid indole alkaloids (including some isomers) and tryptamine. The described HPLC system was applied to the analysis of alkaloids in intergeneric somatic hybrid cell cultures of Rauvolfia serpentina x Rhazya stricta.

Cells, Cultured↗
PubMedDate not supplied

Qualitative determination of false-positive effects in the acetylcholinesterase assay using thin layer chromatography.

A method has been developed to determine the false-positive effects on acetylcholinesterase inhibition in the TLC assay based on Ellman's method. Various aldehydes and amines have been tested in order to determine whether the observed inhibition is due to a true enzyme inhibition or due to the inhibition of the reaction between thiocholine and 5,5'-dithiobis-(2-nitrobenzoic acid). 4-Dimethylaminobenzaldehyde, 3-ethoxy-4-hydroxybenzaldehyde, diethylamine, triethylamine, triethanolamine and tyramine showed real enzyme inhibition, although their activity was about 10(3) times lower than that shown by galanthamine. Heptanal, decanal, cinnamaldehyde, anisaldehyde, benzaldehyde, hexylamine and tryptamine appeared to show a non-specific chemical inhibition. By checking this chemical inhibition on the TLC assay, the true enzyme inhibition could be distinguished from the false-positive chemical inhibition observed in the toluene extract of Nerine bowdenii in the course of isolation of active compounds.

Acetylcholinesterase↗
PubMed2004

Atmospheric pressure matrix-assisted laser desorption/ionization with analysis by ion mobility time-of-flight mass spectrometry.

The use of an atmospheric pressure matrix-assisted laser desorption/ionization (AP-MALDI) source was employed with an atmospheric pressure ion mobility spectrometer (APIMS) and an orthogonal acceleration reflector time-of-flight mass spectrometer (TOFMS) to analyze dipeptide and biogenic amine mixtures from a liquid glycerol 2,5-dihydroxybenzoic acid (DHB) matrix. Improved sensitivities were obtained by the addition of a localized electrical (corona) discharge in conjunction with the AP-MALDI source. Enhanced sample ionization efficiency created by this combination provided an overall elevation in signal intensity of approximately 1.3 orders in magnitude. Combinations of three dipeptides (Gly-Lys, Ala-Lys, and Val-Lys) and nine biogenic amines (dopamine, serotonin, B-phenylethylamine, tyramine, octopamine, histamine, tryptamine, spermidine, and spermine) were resolved in less than 18 ms. In many cases, reduced mobility constants (K(o)) were determined for these analytes for the first time. Ion mobility drift times, flight times, arbitrary signal intensities, and collision-induced dissociation (CID) fragmentation product signatures are reported for each of the samples.

Atmospheric Pressure↗
PubMed2004

Enhancing capillary liquid chromatography/tandem mass spectrometry of biogenic amines by pre-column derivatization with 7-fluoro-4-nitrobenzoxadiazole.

This paper describes a capillary liquid chromatography/tandem mass spectrometry (LC/MS/MS) determination of biogenic amines enhanced by pre-column derivatization with 7-fluoro-4-nitrobenzoxadiazole (NBD-F). Biogenic amines including tryptamine, N-methylsalsolinol, histamine, and agmatine were studied. The biogenic NBD-amine derivatives could be quantitatively enriched in-line on 20 x 0.25 mm capillary columns packed in-house with 5 microm C(8) silica particles. In an electrospray ionization (ESI) source these derivatives were ionized effectively, and collision-induced dissociation (CID) produced predominant characteristic ions allowing sensitive MS/MS detection. Agmatine, a potential neurotransmitter/modulator, was taken as a reference compound to study the analytical figures of merit of the procedure. The detection limit of agmatine was estimated to be 0.6 ng/mL (signal-to-noise (S/N) = 3). A linear calibration curve in the range 15-1000 ng/mL agmatine with an r value of 0.9997 was obtained. Tissue samples of rat brain, stomach, and intestine were analyzed. Minimum sample pre-treatment was needed. Each analysis was accomplished within ca. 12 min. The concentration of agmatine was found to be 0.246, 3.31, and 0.058 microg/g wet tissue in the brain, stomach, and intestine, respectively.

4-Chloro-7-nitrobenzofurazan↗
PubMed1997

Effect of 5-hydroxytryptamine on sodium- and potassium-dependent adenosine triphosphatase and its reactivity toward ouabain.

Activity of vertebrate Na+,K+-ATPase was inhibited by 5-hydroxytryptamine. Inhibition was reversible, and activity could be restored by dilution of 5-hydroxytryptamine (5HT). The ability of indole derivatives to inhibit depended on the presence of a net charge on the third atom of the indole C-3 side chain. Indoles with a net positive charge, such as 5HT, were stronger inhibitors than those with a net negative charge. Derivatives with a net charge of zero were not inhibitors. The ability of indole derivatives to inhibit Na+, K+-ATPase activity decreased in the order 5HT > tryptamine > tryptophanamide > tryptophol > N-acetyl-5-methoxytryptamine > indole-3-acetic acid. Trp did not inhibit either ATPase or pNPPase activity. Charged indole derivatives also inhibited the pNPPase activity of Na+,K+-ATPase. 5HT and tryptophanamide were stronger inhibitors of pNPPase activity than indole-3-acetic acid. Binding of [3H]ouabain was inhibited by 5HT and tryptophanamide. Trp did not inhibit [3H]ouabain binding. The near equilibrium level of [3H]-ouabain binding in the presence of ATP, Mg2+, and Na+ was decreased by 5HT in the manner characteristic of a competitive inhibitor. Enzyme-bound [3H]ouabain could be displaced by 5HT. 5HT was a complex mixed inhibitor of K+ with interactions at two sites, Tris was a competitive inhibitor with interactions at three sites, and ouabain was a simple noncompetitive inhibitor. The data are explained through a model indole binding site containing oppositely charged residues.

Animals↗
PubMed2002

Redox intermediates of plant and mammalian peroxidases: a comparative transient-kinetic study of their reactivity toward indole derivatives.

A comparative study on the reactivity of five indole derivatives (tryptamine, N-acetyltryptamine, tryptophan, melatonin, and serotonin), with the redox intermediates compound I (k2) and compound II (k3) of the plant enzyme horseradish peroxidase (HRP) and the two mammalian enzymes lactoperoxidase (LPO) and myeloperoxidase (MPO), was performed using the sequential-mixing stopped-flow technique. The calculated bimolecular rate constants (k2, k3) revealed substantial differences regarding the oxidazibility of the substrates by redox intermediates at pH 7.0 and 25 degrees C. With HRP it was shown that k2 and k3 are mainly determined by the reduction potential (Eo') of the substrate with k2 being 7-45 times higher than k3. Compound I of mammalian peroxidases was a much better oxidant than HRP compound I with the consequence that the influence of the indole structure on k2 of LPO and MPO was small varying by a factor of only 88 and 38, respectively, which is in strong contrast to a factor of 160,000 determined for k2 of HRP. Interestingly, the k3 values for all three enzymes were very similar. Oxidation of substrates by mammalian peroxidase compound II is strongly constrained by the nature of the substrate. The k3 values for the five indoles varied by a factor of 3,570 (LPO) and 200,000 (MPO), suggesting that the reduction potential of compound II of mammalian peroxidase is less positive than that of compound I, which is in contrast to the plant enzyme.

Animals↗