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At least 271 records · Page 15Linked to original sources
PubMed1987

Tremorigenic effect and inhibition of tryptamine and serotonin receptor binding by beta-carbolines.

The abilities of some naturally occurring beta-carbolines (BCs), dihydro-BCs and tetrahydro-BCs to inhibit the specific binding of 3H-tryptamine (TA), 3H-serotonin (5-HT) and 3H-ketanserine to rat brain membranes and to induce tremor in mice were studied. These compounds, particularly DHBCs and BCs, showed higher affinity for TA binding sites than to 5-HT1 or 5-HT2 binding sites inhibiting the former at nanomolar and the two latter ones at micromolar or high micromolar concentrations. The Ki values for norharmane, harmaline and harmine (17, 18 and 74 nM, respectively) for TA sites indicate the highest affinity so far described for natural beta-carbolines to any receptor sites and thus may indicate their major site of action. among the BC derivatives studied, the before mentioned harmala alkaloids were the most potent inducers of tremor in mice, although the orders of the tremorogenic potency and the binding to TA site did not correlate. It is suggested that especially the tremorigenic effect of BC derivatives is partly based on the binding to specific tryptamine receptors.

Animals↗
PubMed2006

Rhabdomyolysis after ingestion of "foxy," a hallucinogenic tryptamine derivative.

"Foxy methoxy" (chemical name, 5-methoxy-N,N-diisopropyltryptamine) is a hallucinogenic tryptamine that has been abused with increasing frequency since its appearance in the late 1990s. Like other drugs in this class, foxy frequently produces feelings of euphoria, disinhibition, and auditory as well as visual hallucinations. The drug has been linked to adverse effects, including restlessness, agitation, gastrointestinal distress, and muscle tension. In light of the relatively recent advent of foxy as a drug of abuse and given the inability of commercial toxicologic screening tests to detect the presence of hallucinogenic tryptamines, additional adverse effects seem probable. We report ingestion of foxy by a healthy 23-year-old man that resulted in rhabdomyolysis and transient acute renal failure.

5-Methoxytryptamine↗
PubMed1993

Selectivity of sterically fixed tryptamine and 5-methoxytryptamine derivatives for serotonin receptor subtypes, II: Structure-activity relationships and in vitro pharmacology of N-alkyl- and N,N-dialkyl-3- indolylbicyclo-[2.2.1]-heptane-2-amines.

Twenty-four norbornane analogues of tryptamine and 5-methoxytryptamine were investigated for affinity at 5-HT2 receptors of the rat tail artery and proved to be weak non-competitive antagonists of 5-HT. Compound 12 which displayed a marked depression of the concentration-effect curves, was examined for potential interaction with the allosteric binding site of the 5-HT2 receptor. The effects elicited by 12, in the presence and absence of the allosteric activator ketanserin, were atypical and must be attributed to a mechanism, unknown up to now. In radioligand displacement experiments binding data for a set of nine compounds were determined at 5-HT1-like, 5-HT2 and 5-HT3 receptors, indicating subtype selectivity for some analogues. The binding affinity of 8 at 5-HT3 receptors which was comparable with the affinity of the selective 5-HT3 agonist 2-methyl-5-HT, could not be demonstrated on the longitudinal muscle strip of the guinea-pig ileum, partially due to the M3 antimuscarinic activity of 8. Functional studies on the rat oesophageal tunica muscularis mucosae did not reveal 5-HT4 agonist properties for two analogues of 5-methoxytryptamine (8, 16).

5-Methoxytryptamine↗
PubMed1977

Mass spectra of some specifically deuterated tryptamines.

The mass spectra of the four tryptamine derivatives, N-acetyl-5-methoxytryptamine (melatonin), N-acetyl-5-hydroxytryptamine (N-acetyl-serotonin), N,N-dimethyl-5-hydroxtryptamine (bufotenine) and N,N-dimethyl-5-methoxytryptamine (O-methylbufotenine), with specifically labeled [D4] aminoethyl sidechains have been measured. Comparison of these spectra with those of the unlabeled compounds enable the major fragmentations of the compounds to be defined.

Bufotenin↗
PubMed1978

Quantitative assay of the N-methylated metabolites of tryptamine and serotonin by gas chromatography mass spectrometry as applied to the determination of lung indoleethylamine N-methyltransferase activity.

A specific and sensitive method is described for the identifcation and quantification of the N-mono- and dimethylated derivatives of tryptamine and serotonin by gas chromatography mass spectrometry. Deuterated analogues of the amines have been prepared for use as internal standards. The technique has been applied to the determination of indoleethylamine N-methyltransferase activity in rabbit and human lung. No interference from the beta-carboline formation or other side reactions between the substrates and the methyl donor was observed.

Animals↗
PubMed1990

Inhibition of MAO by substituted tryptamine analogues.

Three different acetylenic analogues of tryptamine, in which the side chain is attached at the 2 position of the heterocyclic ring, were studied as inhibitors of MAO-A and MAO-B. IC50 values were determined after 30 min preincubation of the enzyme and inhibitor, at 37 degrees C before assay. Irreversibility and time-dependence of the inhibition were also established in each case. The kinetic parameters defining non-covalent complex formation and covalent adduct formation were calculated for the mechanism-based inhibition of both MAO-A and MAO-B by these compounds.

Animals↗
PubMed1994

Interactions between substituted tryptamine analogues, MAO inhibitors and cytochrome P-450.

The effects of some MAO inhibitors, N-acetylenic analogues of tryptamine, on rat liver microsomal cytochrome P-450 (cyt P-450) have been investigated. All the compounds tested interacted with cyt P-450 with Ks values ranging between 14 and 358 microM (clorgyline Ks = 10.5 microM). Compounds with a tertiary amine and those possessing a secondary amine group in the acetylenic side chain exhibited type I and type II difference spectra, respectively. Aniline hydroxylase activity was inhibited irreversibly and in a time-dependent fashion by all compounds tested with IC50 ranging between 7 x 10(-5) and 7 x 10(-3) M (clorgyline 10(-4) M).

Animals↗
PubMed1987

Comparative analysis of two types of 5-hydroxytryptamine receptor mediating vasorelaxation: differential classification using tryptamines.

Two receptors mediating relaxant responses to 5-hydroxytryptamine (5-HT) were studied comparatively in rings of rabbit jugular vein contracted with U-46619 (10 nmol/l). At low concentrations of 5-HT (0.001-0.1 mumol/l) vascular relaxation was mediated indirectly by the endothelial 5-HT receptor previously described by Leff et al. (1987). In preparations denuded of endothelium, higher concentrations of the amine (0.03-30 mumol/l) caused relaxation responses directly, presumably via a receptor located on the smooth muscle cells. Similarity between the receptors was evident in that both were susceptible to antagonism by methysergide, but resistant to blockade by ketanserin and MDL 72222. In these respects, the receptors qualified for a '5-HT1-like' classification. Consistent with this, 5-carboxamidotryptamine demonstrated a higher agonist potency than 5-HT at the receptor mediating relaxation directly. However, in endothelium-intact jugular vein rings this potency order was reversed, showing that the endothelial 5-HT receptor did not satisfy completely the criteria for a '5-HT1-like' designation. When the activities of a single set of tryptamines were compared in endothelium-intact and -denuded jugular vein rings, different affinity and relative efficacy estimates were obtained, confirming that two distinct 5-HT receptors mediate relaxation responses in this tissue. The most striking difference between these two receptor types was demonstrated by alpha-methyl-5-HT since it expressed a high affinity comparable to 5-HT at the endothelial receptor, but was inactive at the receptor in endothelium-denuded preparations at concentrations up to 30 mumol/l.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Effects of 5,7-dihydroxytryptamine and 6-hydroxydopamine on head-twitch response induced by serotonin, p-chloroamphetamine, and tryptamine in mice.

Head-twitch response (HTR) in mice was induced by intracerebroventricular injection of tryptamine (TRA) as well as serotonin (5-HT) and p-chloroamphetamine (PCA). Pretreatment with 5,7-dihydroxytryptamine enhanced both the 5-HT-induced and the TRA-induced HTR. The PCA-induced HTR, however, was attenuated by the drug. On the other hand, pretreatment with 6-hydroxydopamine did not alter the 5-HT response but enhanced both the PCA- and the TRA-induced response. These results suggest that 5-HT may directly stimulate the post-synaptic receptors, while the PCA response may be based on the release of endogenous 5-HT. The presynaptic component of the central serotonergic system does not appear to be involved in the TRA response. Both PCA and TRA may affect catecholaminergic systems which can suppress the response.

5,7-Dihydroxytryptamine↗
PubMed1984

Tryptamine transport in rat brain slices: a comparison with 5-hydroxytryptamine.

The uptake of [14C]tryptamine (14C-T) and [3H]serotonin (3H-5HT) into slices of rat hypothalamus (HT), fronto-parietal cortex (CX), and caudate nucleus (Cau) has been investigated. In all three brain areas, the uptake of 3H-5HT at 37 degrees C was much greater than that in an ice-bath at 1.0-1.5 degrees C. In contrast, the uptake of 14C-T at 37 degrees C was not much greater than uptake at 1.0-1.5 degrees C. While markedly different amounts of 3H-5HT were accumulated by each of the brain areas studied, the regional uptake of 14C-T was quantitatively similar. In general the uptake of 14C-T was inhibited less than 3H-5HT by cocaine, DNP, ouabain, and decreased Na+ concentrations. Similarly, 14C-T was less susceptible to serotonin uptake inhibitors except in the caudate. It was concluded that though a common indoleamine uptake system accumulates both T and 5HT, a non-specific low affinity or diffusional process also transports both amines and is predominantly responsible for T, but not 5HT, uptake. The spontaneous release, or wash-out, of 14C-T from the caudate was much faster than that of 3H-5HT. In addition, while depolarizing stimuli caused little or no release of 14C-T, large releases of 3H-5HT were observed. T, therefore, does not behave like a conventional neurotransmitter.

Animals↗
PubMed1994

Effects of low- and high-dose tranylcypromine on [3H]tryptamine binding sites in the rat hippocampus and striatum.

Chronic studies were initiated in rats to determine the effects of high- and low-dose tranylcypromine (TCP) on [3H]tryptamine (3H-T) binding sites. Male Sprague-Dawley rats were administered TCP (0.5 or 2.5 mg/kg/day) or vehicle (distilled water) for 4, 10 or 28 days via Alzet minipumps. After decapitation, the hippocampus and striatum were used to prepare membrane fragments for single point 3H-T binding. Hippocampal 3H-T binding was reduced after 10 and 28 days with the low dose and after 4, 10 and 28 days with the high dose. Striatal 3H-T binding was reduced by both doses at all time intervals. The high dose resulted in a significantly greater reduction in striatal 3H-T binding than did the low-dose after 4, 10, and 28 days. These results suggest that a more rapid reduction of 3H-T binding in the hippocampus and/or a greater reduction of 3H-T binding in the striatum by high-dose TCP than by low-dose TCP may be contributing factors in the reported efficacy of the former in refractory depression.

Animals↗
PubMed1983

Output of endogenous monoamine oxidase inhibitor in rats: effect of ethanol, tryptamine and tryptophan.

Contrary to prediction, loading rats with tryptamine, tryptophan or methanol failed to produce any rise in endogenous monoamine oxidase inhibitor output, whilst ethanol administration resulted in a significantly decreased excretion. These findings, which provide no support for the hypothesis that the inhibitor is a beta-carboline, may shed some light on the tranquilizing effect of ethanol in man.

Animals↗
PubMed1993

The effect of side chain substitution at positions 2 and 3 of the heterocyclic ring of N-acetylenic analogues of tryptamine as monoamine oxidase inhibitors.

N-Acetylenic analogues of tryptamine in which the side chain is located at position 2 of the indole ring are compared with those in which the side chain is located at position 3, in terms of their actions as inhibitors of monoamine oxidases A and B. IC50 values at 0 and 30 min of pre-incubation were determined. Time-dependence and irreversible inhibition confirmed that all of them behave as mechanism-based inhibitors. The kinetic constants of each inhibition step were determined for both monoamine oxidase forms and compared between them. In all cases the first-order rate constants for the covalent adduct formation were similar to inhibitor selectivity which is derived solely from differences in affinities for non-covalent binding to the A and B enzymes. Those compounds where the acetylenic side chain was substituted at position 2 of the heterocyclic ring and selective inhibitors of monoamine oxidase A were more potent than those with the side chain in position 3.

Acetylene↗
PubMed1989

Neurotoxic effects of partially oxidized serotonin: tryptamine-4,5-dione.

Neurotoxicity of tryptamine-4,5-dione (4,5-DKT), a partially oxidized form of serotonin, was assessed after microinjection into the lateral ventricle, hippocampus, or cingulate cortex of rats followed by Fink-Heimer staining for axon terminal degeneration. Intracerebroventricular injections of 4,5-DKT resulted in terminal degeneration which was most dense in layers I and III of insular cortex, layer I of cingulate cortex, and the molecular layer of the dentate gyrus. Argyrophilic and probably degenerating neurons were most frequently subjacent to the granule cell layer of the dentate gyrus, layers II, III, and IV of entorhinal cortex, and throughout the insula. Injections of 5-20 micrograms of 4,5-DKT directly into the hippocampus indicated that toxicity was dose-dependent. These injections produced axon terminal degeneration and neuronal argyrophilia in sectors CA1 and CA3 and in the dentate gyrus. Argyrophilic neurons were also observed in layers II, III, and IV of ipsi- and contralateral entorhinal cortices. Injections into anterior and posterior cingulate cortices produced degeneration in the caudate and anterior thalamic nuclei, and contralateral cortex. These results indicate that 4,5-DKT is a novel indole neurotoxin which exhibits a striking propensity for medial limbic system structures including some of those affected in dementia of the Alzheimer type.

Animals↗
PubMed1990

Simultaneous detection of tryptamine and dopamine in rat substantia nigra and raphe nuclei using specific antibodies.

Using a double-labelling procedure, morphological relationships existing between dopaminergic and indoleaminergic neuronal systems in the rat brain were investigated. First, thanks to a tryptamine (T) antiserum, we visualized this indoleamine in all mesencephalic regions and showed that the T-immunoreactivity (IR) seems to overlap with the stainings observed from serotonin and 5-methoxytryptamine antisera. Secondly, using a monoclonal anti-dopamine (DA) antibody and our anti-T antibodies, the simultaneous and specific detection of these compounds enabled us to define the spatial relationships existing between the dopaminergic and tryptaminergic neuronal systems from the substantia nigra (SN) to the raphe nuclei. No co-localization existed, but the intensity of T-IR decreased from back to front, whereas the DA-staining decreased in the opposite way, indicating possible interactions at the end of the SN and the B9 area.

Animals↗
PubMed1985

The effect of caffeine on mouse striatal tryptamine.

The experiments show that the striatal tryptamine accumulation rate as determined after pargyline treatment was increased by the administration of caffeine or theophylline. These increases were correlated with increases in the availability of brain tryptophan.

Animals↗