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At least 1,009 records · Page 56Linked to original sources
PubMed1985

[Changes in and modulation of receptor activity in hepatic encephalopathy].

In hepatic encephalopathy (HE) brain uptake of large neutral amino acids is impaired with tryptophan crossing the blood brain barrier (BBB) to a much larger extent than all other competing amino acids (AA). The disturbance in the steady-state of transmitter is paralleled to the change of their kinetic data. This is reflected by an increase in serotonin (5-HT) synthesis and turnover, while the number of post-synaptic 5-HT1-binding sites is decreased, 5-HT2-receptor activity is dropping to a much smaller extent. On the other hand, presynaptic dopaminergic activity remains unchanged with no change in D2-receptor activity. Valine (VAL) improves the postsynaptic 5-HT function via modulating activity due to a regulatory mechanism at the membranal level in vitro and ex vivo. Furthermore, VAL leads to a significant reduction of serum ammonia (NH4+) and brain NH4+ concentration. VAL is able to antagonize the binding density diminishing effects of NH4+ on 5-HT binding sites. This effect could be characterized by the measurement of VAL binding sites being 5 to 10 fold higher than the number of leucin (LEU)-sites. Considering the chemical bonds involved in the attachment of biogenic amines and aminoacids (Schiff-bases equilibria) the modulating action of NH4+ on neural transmission may be clarified. Tryptamine can displace the postsynaptic binding of 5-HT in brain tissue and is a possible antagonist to physiological and pharmacological effects of 5-HT. The dynamic changes of the kinetic behaviour of tryptamine-binding might demonstrate a compensating effect as shown in an increase of tryptaminergic receptor activity. As a working hypothesis, the different relative strengths of electron-pair donor and -acceptor sites of both compounds are suggested to their complementary physiological interaction. GABA, an inhibitory transmitter of the CNS is diminished in its maximal binding capacity in severe HE and is independent of NH4+ influence. Furthermore, glutamate and aspartate-receptors decrease in experimentally induced hepatic coma. L-LEU shows modulating effects of glutamine binding. Glycin-activity is increased, while naloxone- and D-ala2-methionine-encephalinamid binding are not different from controls. These data demonstrate a different influence of various brain receptors and binding sites by HE and indicate a differentiated disturbance of (neuronal) membrane activity. Therefore disturbed interneuronal dynamics might be important pathophysiological mechanisms underlying hepatic coma.

Ammonia↗
PubMed1985

[Localization of biogenic monoamines in the dura mater of the rat brain].

Quantitative and qualitative composition of catecholamines (noradrenaline and dophamine) and indolalkylamines (serotonin and tryptamine) and their localization have been studied in cells and neural fibers of the rat dura mater. Luminiscent-cytophotometric and electron microscopic methods have revealed two types of cells depositing biogenic monoamines. As demonstrate the experiments with rausedil injection, monoaminocytes of the first type (mast cells) contain predominantly indolalkylamines and a small amount of dophamine. Monoaminocytes of the second type (chromaffin cells) synthesize mainly serotonin and, perhaps, tryptamine. In adrenergic neural fibers only noradrenaline has been found to be present.

Animals↗
PubMed1986

[Karyological and morphological analysis of bovine kidney cells resistant to tryptophan analogs--inhibitors of tryptophanyl-tRNA synthetase].

Karyological and morphological analysis of the wild type MDBK cell line (spontaneously transformed bovine kidney cells) was undertaken. The results were compared with the same data obtained with resistant lines derived from the wild type line after prolonged cultivation with increasing quantities of tryptophanol and tryptamine, competitive analogues of tryptophan. Tetraploids are much more abundant in the resistant lines than in the initial one. In tryptamine-resistant cells a large marker acrocentric chromosome is duplicated in 96% of cells and elongated, due to appearance of an additional segment. In the population of resistant cells bi- and multinuclear cells are abundant as well as giant cells; the nuclei are enlarged and the number of nucleoli is increased. A hypothesis is proposed that resistance to tryptophan analogues is associated with amplification of tryptophanyl-tRNA synthetase gene.

Amino Acyl-tRNA Synthetases↗
PubMedDate not supplied

[Disorders of oxidative deamination of biogenic amines in the myocardium in experimental atherosclerosis].

Statistically significant inhibition of oxidative deamination of several biogenic amines was found in mitochondrial fraction of heart muscle from rabbits and rats with experimental atherosclerosis and hypercholesterolemia, caused by various methods. Sensitivity of oxidative deamination of tryptamine to inhibitory effect of clorgyline (selective inhibitor of mitochondrial monoamine oxidases) was unaltered in rats with experimental hypercholesterolemia. The rate of oxidative deamination of beta-phenyl ethylamine, tryptamine, benzylamine as well as histamine and putrescine was inhibited after treatment of the mitochondrial fragments from healthy rabbit and rat heart muscles with preparations of oxidized linoleic and linolenic acids, concentration of which was increased in tissues under conditions of atherosclerosis.

Animals↗
PubMed1983

Monoamino-oxidase activity in rat pineal gland. Histochemical studies.

Monoamine-oxidase (MAO) activity was detected in rat pineal gland with dopamine, 5-hydroxytryptamine (5-HT), norepinephrine and tryptamine as substrates, and nitroblue tetrazolium salt as electron acceptor. Pinealocytes stained deeply when 5-HT was the substrate. Dopamine and tryptamine substrates gave similar patterns, with moderate activity in the pinealocytes. Norepinephrine reactivity was detected in the nerve-endings.

Animals↗
PubMed1984

[Inhibition of monoamine oxidase A and B in the heart and brain of the rat with amitriptyline, pargyline and pirlindol].

The inhibition of monoamine oxidase (MAO) A and B by amitriptyline, pargyline and pirlindole was measured in heart and brain homogenates of rats with tryptamine and beta-phenylethylamine as substrates. The tricyclic antidepressant amitriptyline inhibited MAO B stronger in the brain (Ki = 8.41 X 10(-6) mol/l) as well as in the heart (Ki = 7.03 X 10(-5) mol/l) compared to the A-form (1.51 X 10(-4) and 1.03 X 10(-4) mol/l, respectively). Pargyline diminished the activity of both enzyme forms of the heart in the same range (4.29 and 1.60 X 10(-6) mol/l), whereas in the brain the B-form was blocked in a more pronounced manner, too (5.80 X 10(-8) and 4.01 X 10(-6) mol/l, respectively). In contrast to amitriptyline and pargyline pirlindole inhibited the MAO with tryptamine as a substrate in the brain 100 times (2.49 X 10(-7) mol/l) and in the heart nearly 1000 times (3.42 X 10(-8) mol/l) more than with phenylethylamine as a substrate (5.21 and 5.99 X 10(-5) mol/l, respectively). These results show that amitriptyline and pargyline are relatively selective inhibitors of MAO B, whereas pirlindole blocks the A-form of MAO much stronger than MAO B.

Amitriptyline↗
PubMed1984

[Conjugated dinitrocompound dianions as inhibitors of the oxidative deamination of monoamines].

The conjugated derivatives--1.4-dinitrobutene-2, 1,4-dinitro-2-methylbutene-2, 1,4-dinitro-2,3-diphenylbutene-2 sodium salts, as well as dinitromethane sodium salt and beta-nitrostyrol, the inhibitors of oxidative deamination of serotonin, tyramine, tryptamine and benzylamine in bovine liver mitochondria, were studied. All the derivatives under study were found to be active inhibitors of monoamine oxidase catalyzing the oxidative deamination of serotonin, tyramine and tryptamine. In a far lesser degree these preparations inhibited the deamination of benzylamine, a specific substrate for monoamine oxidase B. All the dinitrocompound dianions, with the exception of 1,4-dinitro-2,3-diphenylbutene-2 disodium salt, a non-competitive inhibitor of oxidative deamination of the four substrates under study, cause competitive reversible inhibition of monoamine oxidase.

Alkenes↗
PubMedDate not supplied

[The reaction of the chick embryo amnion to indolamines].

Studies have been made of the effect of serotonin and tryptamine on contractile activity of nerve-free smooth muscle strip from the amnion of 7-19-day chick embryos. It was shown that stimulatory effect of indolamines depends on the age of embryos. Within 7-9 days of incubation, there was a delay in the onset of the response, the sensitivity being rather low (threshold dose for serotonin-5 microM); prolonged washing before each application of the drugs was usually necessary. At the 13-15th day, the reaction-becomes rather quick, being easily abolished by washing procedure; the sensitivity and the level of maximum reaction increase (for serotonin, mean Kd and Pmax values were equal to 0.3 microM and 62.2 mg/mg tissue respectively). Developmental changes in responses to tryptamine are similar to those described for serotonin. The effectiveness of serotonin at the 7-9th day of incubation is significantly lower than that of Ach, whereas at the 13-15th day the value of Kd is similar to that for Ach, Pmax being often higher than for the latter. The data obtained are discussed in relation to proliferation changes in amniotic tissue.

Acetylcholine↗
PubMed1993

[The amine-forming ability of Aeromonas spp].

Motile Aeromonas (A.) species are considered international more and more as potential food poisoning organisms. Their ability to produce biogenic amines, products of metabolism, which in case can cause a disease, was only searched insufficiently till now. 50 strains of the species A.hydrophila, A.sobria, A.caviae and the non-motile species A.salmonicida were included in the tests for amine producing potency. Qualitative investigations to the formation of histamine, tryptamine, and tyramine were ensued by the help of thin layer chromatography. Quantitative investigations were only done in respect of the production of tyramine, which had been proved qualitatively in several strains, while histamine and tryptamine were not produced. Concentrations of tyramine with foodhygienic relevance were found out partially.

Aeromonas↗
PubMed1976

Selectivity of 4-methoxyphenethylamine derivatives as inhibitors of monoamine oxidase.

It has been established that the oxidative deamination of tyramine by monoamine xodase is inhibited by (+/-)-4-methoxy-beta-hydroxyphenethylamine and its N-methylated derivatives. This particular series of compounds does not inhibit the action of monoamine oxidase when tryptamine is used as the substrate. In contrast, 4-methoxyphenethylamine and its N-methylated homologs inhibit the monoamine oxidase-catalyzed deamination of both tyramine and tryptamine.

Animals↗
PubMed2000

Determination of biogenic amines in cheese by ion exchange chromatography.

A sensitive, fully automated method, yielding reproducible results, was developed for the determination of relevant biogenic amines in cheese. Histamine, tyramine, putrescine, cadaverine, tryptamine, agmatine, spermidine and spermine were separated in the ion exchanger of OSTION LG ANB column of the automatic amino acid analyser Mikrotechna 339 T. Elution was carried out at 60 degrees C using a system of two buffers. The samples were extracted and precipitated by trichloroacetic acid and purified, after removal of fat, by membrane filtration. The recovery for individual amines in cheese ranged between 86% and 108%. The detection limit was of 1-5 mg of the respective amine per 1 kg of cheese and the method was linear within the dose range of 0.1-10 micrograms (for tryptamine 0.5-10 micrograms).

Amino Acids↗
PubMed1991

Resolution of end-to-end diffusion coefficients and distance distributions of flexible molecules using fluorescent donor-acceptor and donor-quencher pairs.

We used time-dependent fluorescence energy transfer, time-dependent collisional quenching, and global analysis of the data resulting from these through-space and contact interactions to recover the end-to-end distance distributions and diffusion coefficients of flexible fluorescent molecules. The fluorescence decays of covalently linked tryptamine-acceptor and tryptamine-quencher pairs were measured by the frequency-domain method. These data were fit using numerical solutions of the differential equation, which predicts the time- and distance-dependent population of the excited state donors in the presence of energy transfer or collisional quenching, followed by transformation to the frequency domain for nonlinear least-squares comparison with the experimental data. We found that the energy transfer data for the donor-acceptor pair alone were adequate to recover the starting distribution and the end-to-end diffusion coefficient; however, the resolution is dramatically improved by the use of both the through-space and contact interactions.

Mathematics↗
PubMed1976

Effect of oral contraceptives on platelet monoamine oxidase, monoamine excretion, and adrenocortical function.

Studies with animals indicate that there are cyclical changes in the monoamine oxidase (MAO) activity of brain and uterus, and that these changes may be due to changes in estrogen and progesterone levels. To determine if oral contraceptives (OC) alter the tissue MAO activity of healthy women, we measured platelet MAO activity in 7 control women and in 7 women who were receiving combination estrogen-progesterone OC. The platelet MAO of the control women and the women receiving OC did not differ with the use of tryptamine and serotonin as MAO substrates. The two groups did not differ with respect to the following: serum serotonin, plasma tryptophan, plasma tyrosine, and the urinary excretion of tryptamine, tyramine, serotonin, 5-hydroxyindoleacetic acid, creatinine, 17-hydroxycorticosteroids, 17-ketosteroids, and urinary free cortisol. The subjects receiving OC had higher plasma cortisol concentrations than the controls. Two women in the seventh month of uncomplicated pregnancy, who underwent these studies, had higher plasma cortisol and urinary 17-ketosteroid excretion than control subjects. In the remaining tests the results of pregnant subjects did not differ from those of control subjects. We conclude that tissue MAO activity is not altered by OC or pregnancy.

Adrenal Cortex↗
PubMed1988

Further insights into the oxidation chemistry of 5-hydroxytryptamine.

An important product of electrochemical oxidation of 5-hydroxytryptamine (5-HT) in acid solution is the purple compound tryptamine-4,5-dione (6). However, any attempt to concentrate a solution containing 6 causes it to disappear. The most important reaction of 6 is dimerization to give another purple compound 7,7'-bi-(5-hydroxytryptamine-4-one). Dione 6 can also apparently react with 2,4'-bi-5-hydroxytryptamine to give the trimer 4-[7'-(tryptamine-4,5-dione)]-2,4''-bi-5-hydroxytryptamine. Finally, 6 and other oxidation products of 5-HT react during the concentration step to yield what appears to be a trimer or perhaps a higher oligomer. This oligomer has not been identified, but it has been shown to decompose to give, in part, the neurotoxin 5-hydroxytryptamine-4,7-dione.

Chemical Phenomena↗
PubMed1999

Human indolethylamine N-methyltransferase: cDNA cloning and expression, gene cloning, and chromosomal localization.

Indolethylamine N-methyltransferase (INMT) catalyzes the N-methylation of tryptamine and structurally related compounds. We recently cloned and characterized the rabbit INMT cDNA and gene as a step toward cloning the cDNA and gene for this enzyme in humans. We have now used a PCR-based approach to clone a human INMT cDNA that had a 792-bp open reading frame that encoded a 263-amino-acid protein 88% identical in sequence to rabbit INMT. Northern blot analysis of 35 tissues showed that a 2.7-kb INMT mRNA species was expressed in most tissues. When the cDNA was expressed in COS-1 cells, the recombinant enzyme catalyzed the methylation of tryptamine with an apparent K(m) value of 2.9 mM. The human cDNA was then used to clone the human INMT gene from a human genomic BAC library. The gene was 5471 bp in length, consisted of three exons, and was structurally similar to the rabbit INMT gene as well as genes for nicotinamide N-methyltransferase and phenylethanolamine N-methyltransferase in several species. All INMT exon-intron splice junctions conformed to the "GT-AG" rule, and no canonical TATA or CAAT sequences were present within the 5'-flanking region of the gene. Human INMT mapped to chromosome 7p15.2-p15.3 on the basis of both PCR analysis and fluorescence in situ hybridization. Finally, two possible single nucleotide polymorphisms were identified within exon 3, both of which altered the encoded amino acid. The cloning and expression of a human INMT cDNA, as well as the cloning, structural characterization, and mapping of its gene represent steps toward future studies of the function and regulation of this methyltransferase enzyme in humans.

Amino Acid Sequence↗
PubMed1998

Influence of Polarity and Viscosity of the Micellar Interface on the Fluorescence Quenching of Pyrenic Compounds by Indole Derivatives in AOT Reverse Micelles Solutions.

The fluorescence quenching of the pyrene derivatives (4-(1-pyrenyl)butyl) trimethylammonium bromide (PBTMA), (1-(1-pyrenyl)methyl) trimethylammonium iodide (PMTMA), and 1-pyrene sulfonic acid (PSA) by indole methyl substituted in positions 1 and 2, tryptophan and tryptamine, was studied in AOT/heptane reverse micelles as a function of R = [water]/[AOT]. In these systems the pyrenic probes are associated to the micellar interface. Bulk and intramicellar quenching rate constants were determined for neutral indoles. The quenching rate constants of PBTMA by indole or 1,2-dimethylindole increase with R, whereas for those for PMTMA or PSA by indole the increment is much smaller. For the quenchers, tryptophan and tryptamine, that are bound to the interface of the reverse micelle, the bimolecular intramicellar quenching rate constant is much lower than in water. The results can be explained by a high microviscosity of the interface, and a micropolarity similar to that sensed by other probes. Moreover, the observed trend in the rate constants when R is varied is in line with the reported changes in micropolarity and microviscosity. Laser flash photolysis experiments show that in these systems the main result of the quenching process is the formation of the excited triplet of the probe. Copyright 1998 Academic Press.

Journal Article↗
PubMed1993

5-Hydroxytryptamine (5-HT) contracts the guinea-pig isolated iliac artery via 5-HT1-like and 5-HT2 receptors.

The characterization of 5-hydroxytryptamine (5-HT) receptors mediating contractions of the guinea-pig isolated iliac artery was studied when the basal tone was slightly increased by prostaglandin F2 alpha (PGF2 alpha). In the presence of ketanserin (1 mumol/l), 5-HT and several 5-HT receptor agonists induced contractile responses with the rank order of agonist potency: 5-HT = 5-carboxyamidotryptamine (5-CT) = lysergol > ergometrine = methylergometrine > RU 24969 approximately 5-methoxytryptamine (5-MeOT) > methysergide > sumatriptan > tryptamine. Concentration-effect curves to the ergot alkaloids, lysergol, ergometrine, methylergometrine and methylsergide, were biphasic. In the presence of ketanserin (1 mumol/l), contractile responses to 5-HT, 5-CT, RU 24969, 5-MeOT, sumatriptan and tryptamine were antagonized by methiothepin (30 nmol/l) and flesinoxan (3 mumol/l) with approximate pKB values of 8.5-9.0 and 6.0-6.3, respectively. The first phase of contraction produced by the ergot alkaloids, lysergol, ergometrine, methylergometrine and methysergide, were blocked by methiothepin (30 nmol/l) and flesinoxan (3 mumol/l), respectively, with approximate pKB values about 8.4-8.7 and 6.2-6.4, respectively. The mechanism underlying the second phase of contraction remains to be established. Maximum responses of the concentration-effect curves to 5-HT (1 nmol/l-1 mumol/l) were concentration-dependently depressed by ketanserin (1 nmol/l-1 mumol) and spiperone (30 nmol/l-0.3 mumol/l) and reached approximately 60% of the 5-HT maximum response in the presence of ketanserin (1 mumol/l) and spiperone (0.1 mumol/l), respectively. Agonist potency of 5-HT was not affected by the antagonists.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Characterization of an endothelial 5-hydroxytryptamine (5-HT) receptor mediating relaxation of the porcine coronary artery.

The pharmacological properties of the endothelial 5-hydroxytryptamine (5-HT) receptors involved in relaxation of vascular smooth muscle were determined in rings of pig coronary artery contracted with 10 nmol/l of the thromboxane A2 receptor agonist 9,11-dideoxy-11 alpha,9 alpha-epoxy-methano-prostaglandin F2 alpha (U 46619). (1) In the presence of 10 mumol/l ketanserin, relaxation was obtained with: 5-HT (apparent pD2 value 7.00), 5-carboxamidotryptamine (5-CONH2-T; 6.42), 5-aminotryptamine (5-NH2-T; 5.96), 5-methoxytryptamine (5-OCH3-T; 5.92), tryptamine, 7-trifluoromethyl-4(4-methyl-1-piperazinyl)-pyrrolo(1,2-a)quinoxaline maleate (CGS 12066 A) and 5-methoxy-3(1,2,3,6-tetrahydro-4-pyridinyl)-1H-indole succinate (RU 24969). The maximum relaxation obtainable with the agonists was about 40-60% of the U 46619-induced contraction and the concentration-response curves for 5-HT, 5-NH2-T and 5-OCH3-T were bell-shaped. The endothelium-dependence of this effect (i.e. the failure to relax the artery in endothelium-denuded preparations) was demonstrated for 5-HT, 5-CONH2-T, RU 24969, CGS 12066A and tryptamine. (2) 8-Hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT), 4-hydroxytryptamine, quipazine and yohimbine were ineffective in decreasing the tension of arteries with or without endothelium. Ipsapirone elicited full relaxation of U 46619-induced contraction, but this effect was not endothelium-dependent.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗