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PubMedDate not supplied

Catabolism of intracerebroventricularly injected 5-hydroxytryptamine in mouse: effect of coinjection of tryptamine and several pretreatments.

The catabolism of intracerebroventricularly injected 5-hydroxytryptamine in mouse brain was investigated. Pretreatment of animals with the 5-hydroxytryptamine type 1 receptor antagonist metergoline, the 5-hydroxytryptamine type 2 receptor antagonist ketanserin, the 5-hydroxytryptamine reuptake inhibitor fluoxetine, or the selective 5-hydroxytryptamine neurotoxin 5,7-dihydroxytryptamine failed to alter the rate of catabolism of intracerebroventricularly administered 5-hydroxytryptamine. The monoamine oxidase inhibitor tranylcypromine effectively blocked degradation of injected 5-hydroxytryptamine and accumulation of 5-hydroxyindoleacetic acid. Coinjection of tryptamine with 5-hydroxytryptamine reduced the rate of conversion of 5-hydroxytryptamine to 5-hydroxyindoleacetic acid. These results indicate that intracerebroventricularly administered 5-hydroxytryptamine is removed by a monoamine oxidase dependent system. This catabolism is not affected by inhibition of presynaptic uptake, 5-hydroxytryptamine receptor type 1 or type 2 blockade, or destruction of serotonergic nerve terminals. The coadministration of tryptamine may prolong the residence period of 5-hydroxytryptamine through competition for monoamine oxidase.

Animals↗
PubMed1977

In vitro half-life of 14-C-tryptamine in whole blood of drug-free chronic schizophrenic patients.

The authors found higher in vitro 14C-tryptamine half-lives in the blood of 10 drug-free chronic schizophrenic patients than in the blood of 13 mentally normal control subjects. This finding was negatively correlated for both groups with platelet MAO activity. Repeated determinations of in vitro 14C-tryptamine half-lives over a period of 5 months were positively correlated for the patients, although some blood samples showed statistically significant variability.

Adult↗
PubMed2004

Investigation of intermolecular interaction in molecular complex of tryptamine and benzoic acid by solid-state 2D NMR.

Solid-state NMR spectra and powder X-ray diffraction of the two-component molecular complex composed of tryptamine and benzoic acid were observed to investigate the intermolecular interaction in the molecular complex. 1D (13)C CP/MAS NMR spectrum and powder X-ray diffraction pattern of the complex was clearly different from the convolution of each spectrum of the single component. 2D (1)H-(13)C heteronuclear-correlation (HETCOR) NMR technique indicated that the intermolecular interaction between the primary amine of tryptamine and the carboxyl group of benzoic acid must be related to the complex formation.

Benzoic Acid↗
PubMed1999

Tryptamine, serotonin and catecholamines: an immunocytochemical study in the central nervous system.

Tryptamine, a serotonin-related indolamine, could be involved in the modulation of catecholaminergic and serotoninergic systems interaction. Despite previous reports on this topic, the morphological relationship among these systems is not well described. We studied the interaction among serotoninergic and catecholaminergic with tryptaminergic systems by double immunostaining at the level of light microscopy. Mesencephalic rat brain sections treated according to the Schiff quenching method were double immunostained using peroxidase and fluorescein labeled antibodies. Primary antibodies to anti-tryptophan hydroxylase (TrpOH), anit-tyrosine hydroxylase (TH) and anti-tryptamine (T) were used to demonstrate serotoninergic, catecholaminergic and tryptaminergic neurons respectively. A morphometric study was performed in order to analyze the different morphological characteristics of each system. The results showed that (i) T+ and TrpOH+ neurons are localized in the same areas but their morphology is significantly different. Moreover morphometric parameters of T+ neurons were significantly different from those TrpOH+ or TH+ neurons; (ii) The number of TrpOH+ neurons was larger than T+ neurons; (iii) T+ neurons were dominant in the lateral dorsal raphe nucleus. TrpOH+ neurons were more numerous in the central area of the dorsal raphe nucleus; (iv) Coexpression of TrpOH and T was demonstrated in the somata of dorsal raphe nucleus neurons; (v) TrpOH+ neurons from raphe nuclei and TH+ neurons from substantia nigra are contacted by T+ fibres. The present morphological evidence supports a functional relationship among these three aminergic systems.

Animals↗
PubMed1977

Interaction of drugs with apomorphine, tryptamine and norepinephrine. A new 'in vivo' approach: the ATN-test in rats.

A new experimental test procedure is described for the 'in vivo' study of drug interactions with dopamine (DA), 5 hydroxy-tryptamine (5-HT) and norepinephrine (NE). The ultimate aim of this study is to provide an empirical evaluation of the relative specificity with which drugs may affect particular neurotransmitter systems, and to allow a classification of new drugs in this respect. The data indicate that, within certain dosage limits, compounds may modulate specifically a single component of the test procedure and may thus be considered as interacting specifically to modify one neurotransmitter system: i.e. DA in the apomorphine-test (e.g. pimozide), 5-HT in the tryptamine-test (e.g. pizotifen) and NE in the norepinephrine-test (e.g. phenoxy-benzamine). Higher doses of the same compounds may, however, excert effects on other neurotransmitter systems as well, and these actions may be classified as nonspecific. Thus the concept of drug specificity as applied in the present study, is not exclusive, but refers to the dissociation, in terms of doses, which exists between a drug's effect on one neurotransmitter system and its possible effects on other systems. The ATN-test separates and delineates, in terms of doses, the specific and nonspecific effects of drugs.

Animals↗
PubMed1990

[Serotonin and tryptamine metabolism in the acute hepatic failure model--changes in tryptophan and its metabolites in the liver, brain, kidney and serum].

When trinitrophenylated (TNP) hepatocytes and lipopolysaccharide (LPS) are intravenously injected into TNP-liver protein sensitized guinea pigs, massive hepatic cell necrosis was induced in most of mice. Using this experimental acute hepatic failure model, the tryptophan metabolism in the liver, brain, kidney and serum was studied. As a result, the tryptophan level was remarkably high in all three organs and serum, and the metabolism of both the tryptamine pathway and serotonin pathway was induced. Also, in the brain, the tryptamine metabolism was more induced compared to the serotonin. These results suggest that the metabolites of tryptophan may be involved in this acute hepatic failure model.

Acute Disease↗
PubMed1978

Modification of the effects of LSD-25, d-amphetamine and tryptamine on electrically evoked responses in the visual system by methiothepin and octoclothepin.

LSD-25 (32 microgram/kg), d-amphetamine (3.2 mg/kg), and tryptamine (320 to 3200 microgram/kg) given intravenously depressed the response recorded in the visual cortex to electrical stimulation of the optic chiasm of the chloralose anesthetized cat. Relatively large doses of 1 mg/kg of the dibenzothiepin derivatives, methiothepin and octoclothepin, antagonized the depressant effects of both LSD-25 and tryptamine to a greater degree than d-amphetamine.

Animals↗
PubMed1978

Evidence for the presence of m-tyramine, p-tyramine, tryptamine, and phenylethylamine in the rat brain and several areas of the human brain.

Postmortem human brains have been obtained from four nonpsychiatric patients, aged 59-70 years. Regional analysis of the trace amines phenylethylamine, p-tyramine, m-tyramine, and tryptamine has indicated that the amines are distributed heterogeneously throughout the brain, but are most concentrated in the basal ganglia. Although the levels are very low, evidence obtained from animal studies has indicated that the trace amines have a very rapid turnover rate. Their presence in a brain synaptosomal fraction suggests a possible involvement in the process of neurotransmission. Postmortem changes in human brain amines are discussed in relation to those occurring postmortem in the rat brain, in which phenylethylamine, p-tyramine, and tryptamine have been shown to increase to levels greater than those prevailing in vivo.

Aged↗
PubMed1981

Serotonin autoreceptors on dorsal raphe neurons: structure-activity relationships of tryptamine analogs.

A series of indole-ethylamines were tested for their ability to suppress the spontaneous firing of single dorsal raphe serotonergic neurons in the rat. The compounds were all derivatives of either tryptamine or N,N-dimethyltryptamine possessing hydroxy or methoxy substituents on the benzene ring portion of the indole nucleus. Their activity was assessed using quantitative microiontophoresis or following systemic (intravenous) administration. The serotonin autoreceptor or so-called "S2 receptor" mediating the inhibition of raphe serotonergic neurons was found to exhibit a high degree of structural specificity among the closely related tryptamine analogs. The following structure-activity rules were demonstrated: (1) for either hydroxy or methoxy derivatives, the relative favorability of the ring positions conforms to the series 5 much greater than 4 greater than 6; (2) methoxy derivatives are more sensitive to a shift of the ring substituent from the 5- to the 4- or 6-positions than are hydroxy compounds; and (3) activity is enhanced by N,N-dimethylation. Furthermore, addition of a methyl group at the 7-position of 5-methoxy-N,N-dimethyltryptamine markedly reduces the activity of this potent agonist. Of the radioligands which label brain serotonin receptors, the pharmacological characteristics of D-[3H]lysergic acid diethylamide binding best correspond to those displayed by the S2 receptor as determined in the present physiological analysis, although sufficient data are not yet available to make a complete comparison.

Animals↗
PubMed1981

Agonist potencies of tryptamine derivatives at pre- and postjunctional receptors in canine saphenous vein.

Strips form canine saphenous veins were incubated with (3H)-noradrenaline and mounted for superfusion. 5-Hydroxytryptamine (5-HT inhibited the release of tritium caused by sustained electrical stimulation (2 Hz, 150 mA, 0.1 msec) being about 10 times more potent than noradrenaline. 5-HT inhibited contractions induced by intermittent electrical stimulation at 2 Hz but increased the tone of the preparations in the absence of stimulation. Agonist potencies of tryptamine derivatives at prejunctional 5-HT receptors were determined by calculating those concentrations which would reduce the contractile effect of 2 Hz to that of 1 Hz, agonist potencies at postjunctional 5-HT receptors were determined by estimating the concentration which produces 50% of maximum response (pD2 values). Comparison of the agonist potencies at pre- and postjunctional receptors of various tryptamine derivatives suggest that in canine saphenous vein the two types of 5-HT receptor are structurally similar.

Animals↗
PubMed1997

[Deodorant effects of champignon extract and repressive effects on production of indole and tryptamine in vivo].

Champignon extract has potent deodorant effects, and its repressive effects on bad smells generated by the decomposition of fishery products are especially marked. Utilizing the amount of ammonical nitrogen, indoleacetic acid and tryptamine generated as the standard criteria, the deodorant effects of champingnon were evaluated. In an in vitro test, chicken liver homogenate was decomposed by incubating at 37 degrees C and with the progress of its decomposition, ammonical nitrogen was generated. Champignon extract was shown to have the ability to repress the generation of ammonical nitrogen. For an in vivo test, an excessive amount of tryptophan was orally administered to domestic rabbits resalting in an increase in blood levels of indoleacetic acid and tryptamine. Champignon extract given concomitantly rapidly reduced blood levels of the two compounds to negligible levels.

Animals↗
PubMed1982

Tetrahydro-beta-carbolines: affinities for tryptamine and serotonergic binding sites.

The affinities of four tetrahydro-beta-carbolines at [3H]tryptamine, [3H]5-HT (5-HT1), and [3H]spiperone (5-HT2) binding sites in rat cerebral cortex were investigated. The unsubstituted tetrahydro-beta-carboline was the most potent of the four compounds at all three binding sites, but was 200-400 times more potent at the tryptamine site than at either of the serotonin sites.

Animals↗
PubMed1991

Characterization of rat platelet serotonin receptors with tryptamine agonists and the antagonists: ketanserin and SCH 23390.

Current literature suggests that the platelet 5-HT2 receptor, thought to be the only active platelet serotonin (5-HT) receptor, may be both heterogeneous and not the sole 5-HT receptor subtype on platelet membranes. The present studies used more selective tryptamine agonists, and the antagonists ketanserin and SCH 23390 to characterize rat platelet 5-HT receptors in vitro. The present studies also addressed anticoagulant effects (citrate versus heparin) on platelet 5-HT aggregation in the rat. 5-HT was less potent at enhancing ADP-induced aggregation in heparinized rat platelet rich plasma (PRP) as compared to citrated PRP. However, potency and maximum aggregation to ADP were greater in heparinized platelets. In citrated rat PRP, the selective tryptamine agonists, 5-carboxamidotryptamine (5-CT) and 2-CH3-5-HT, produced little change in the baseline ADP-induced aggregation and induced platelet shape change only in higher concentrations (greater than 1 microM). In contrast, alpha-CH3-5-HT-induced shape change and enhancement of ADP aggregation were superimposable with that of 5-HT itself suggesting 5-HT2 receptor activation. The antagonists, ketanserin and SCH 23390, inhibited 5-HT enhancement of ADP-induced aggregation with affinity constants consistent with the presence of 5-HT2 receptors as well. Studies with heparinized rat PRP did not unmask activity to 5-CT or 2-CH3-5-HT. Thus, although reports of multiple platelet 5-HT receptors exist, the only detectable, functional 5-HT receptor to enhance aggregation in rat platelets was probably of the 5-HT2 type.

Animals↗
PubMed2005

Endogenous psychoactive tryptamines reconsidered: an anxiolytic role for dimethyltryptamine.

The presence of the potent hallucinogenic psychoactive chemical N,N-dimethyltryptamine (DMT) in the human body has puzzled scientists for decades. Endogenous DMT was investigated in the 1960s and 1970s and it was proposed that DMT was involved in psychosis and schizophrenia. This hypothesis developed from comparisons of the blood and urine of schizophrenic and control subjects. However, much of this research proved inconclusive and conventional thinking has since held that trace levels of DMT, and other endogenous psychoactive tryptamines, are insignificant metabolic byproducts. The recent discovery of a G-protein-coupled, human trace amine receptor has triggered a reappraisal of the role of compounds present in limited concentrations in biological systems. Interestingly enough, DMT and other psychoactive tryptamine hallucinogens elicit a robust response at the trace amine receptor. While it is currently accepted that serotonin 5-HT(2A) receptors play a pivotal role in the activity of hallucinogenic/psychedelic compounds, we propose that the effects induced by exogenous DMT administration, especially at low doses, are due in part to activity at the trace amine receptor. Furthermore, we suggest that endogenous DMT interacts with the TA receptor to produce a calm and relaxed mental state, which may suppress, rather than promote, symptoms of psychosis. This hypothesis may help explain the inconsistency in the early analysis of endogenous DMT in humans. Finally, we propose that amphetamine action at the TA receptor may contribute to the calming effects of amphetamine and related drugs, especially at low doses.

Anxiety↗
PubMed2005

Photoinduced processes in protonated tryptamine.

The electronic excited state dynamics of protonated tryptamine ions generated by an electrospray source have been studied by means of photoinduced dissociation technique on the femtosecond time scale. The result is that the initially excited state decays very quickly within 250 fs. The photoinduced dissociation channels observed can be sorted in two groups of fragments coming from two competing primary processes on the singlet electronic surface. The first one corresponds to a hydrogen-atom loss channel that creates a tryptamine radical cation. The radical cation subsequently fragments to smaller ions. The second process is internal conversion due to the H-atom recombination on the electronic ground state. Time-dependent density functional theory calculations show that an excited pisigma* state dissociative along the protonated amino N-H stretch crosses both the locally excited pipi* state and the electronic ground state S(0) and thus triggers the photofragmentation reactions. The two processes have equivalent quantum yields, approximately equal to 50% of the fragments coming from the H-atom loss reaction. The two primary reaction paths can clearly be distinguished by their femtosecond pump/probe dynamics recorded on the different fragmentation channels.

Journal Article↗
PubMed2005

Direct measurement of the energy thresholds to conformational isomerization in tryptamine: experiment and theory.

The methods of stimulated emission pumping-hole filling spectroscopy (SEP-HFS) and stimulated emission pumping population transfer spectroscopy (SEP-PTS) were applied to the conformation-specific study of conformational isomerization in tryptamine [TRA, 3-(2-aminoethyl)indole]. These experimental methods employ stimulated emission pumping to selectively excite a fraction of the population of a single conformation of TRA to well-defined ground-state vibrational levels. This produces single conformations with well-defined internal energy, tunable over a range of energies from near the zero-point level to well above the lowest barriers to conformational isomerization. When the SEP step overcomes a barrier to isomerization, a fraction of the excited population isomerizes to form that product. By carrying out SEP excitation early in a supersonic expansion, these product molecules are subsequently cooled to their zero-point vibrational levels, where they can be detected downstream with a third tunable laser that probes the ground-state population of a particular product conformer via a unique ultraviolet transition using laser-induced fluorescence. The population transfer spectra (recorded by tuning the SEP dump laser while holding the pump and probe lasers fixed) exhibit sharp onsets that directly determine the energy thresholds for conformational isomerization in a given reactant-product conformer pair. In the absence of tunneling effects, the first observed transition in a given X-Y PTS constitutes an upper bound to the energy barrier to conformational isomerization, while the last transition not observed constitutes a lower bound. The bounds for isomerizing conformer A of tryptamine to B(688-748 cm(-1)), C(1)(860-1000 cm(-1)), C(2)(1219-1316 cm(-1)), D(1219-1282 cm(-1)), E(1219-1316 cm(-1)), and F(688-748 cm(-1)) are determined. In addition, thresholds for isomerizing from B to A(<1562 cm(-1)), B to F(562-688 cm(-1)), and out of C(2) to B(<747 cm(-1)) are also determined. The A-->B and B-->A transitions are used to place bounds on the relative energies of minima B relative to A, with B lying at least 126 cm(-1) above A. The corresponding barriers have been computed using both density functional and second-order many-body perturbation theory methods in order to establish the level of theory needed to reproduce experimental results. While most of the computed barriers match experiment well, the barriers for the A-F and B-F transitions are too high by almost a factor of 2. Possible reasons for this discrepancy are discussed.

Journal Article↗
PubMed2006

Conformational identification of tryptamine embedded in superfluid helium droplets using electronic polarization spectroscopy.

We report electronic polarization spectroscopy of tryptamine embedded in superfluid helium droplets. In a dc electric field, dependence of laser induced fluorescence from tryptamine on the polarization direction of the excitation laser is measured. Among the three observed major conformers A, D, and E, conformers D and E display preference for perpendicular excitation relative to the orientation field, while conformer A is insensitive to the polarization direction of the excitation laser. We attribute the behavior of conformer A to the fact that the angle between the permanent dipole and the transition dipole is close to the magic angle. Using a linear variation method, we can reproduce the polarization preference of the three conformers and determine the angle between the transition dipole and the permanent dipole. Since the side chain exerts small effect on the direction of the transition dipole in the frame of the indole chromophore, all three conformers have a common transition dipole more or less in the indole plane at an angle of approximately 60 degrees relative to the long axis of the chromophore. The orientation of the side chain, on the other hand, determines the size and direction of the permanent dipole, thereby affecting the angle between the permanent dipole and the transition dipole. For conformer D in the droplet, our results agree with the Anti(ph) structure, rather than the Anti(py) structure. Our work demonstrates that polarization spectroscopy is effective in conformational identification for molecules that contain a known chromophore. Although coupling of the electronic transition with the helium matrix is not negligible, it does not affect the direction of the transition dipole.

Journal Article↗
PubMed1960

Structure-activity relationship of tryptamine analogues on the heart of Venus mercenaria.

A number of tryptamine analogues and other exciter agents have been tested on the heart of Venus mercenaria. The method of estimation of potency, especially for irreversibly acting compounds, is discussed. Specificity of action with respect to the site of action of 5-hydroxytryptamine is defined experimentally. The specific activity of tyramine and phenethylamine and the non-specific excitatory action of indole and skatole indicate that the indole ring is neither necessary nor sufficient for 5-hydroxytryptamine-like activity. Tryptamine analogues differ in mode of action as well as potency. Congeners without a 5-hydroxyl group tend to act more slowly and irreversibly as well as less strongly than 5-hydroxytryptamine. Methyl substitution also increases the time of action and difficulty of reversal. However, the potency of such compounds may be increased or decreased depending upon the position of substitution and the presence of the 5-hydroxyl group. The relations between structure and potency and mode of action are discussed. Suggestions are made concerning the effective conformation of the 5-hydroxytryptamine molecule and the nature of its receptor.

Animals↗