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PubMed1980

Structural requirements for uptake into serotoninergic neurones.

Experiments were performed to examine whether non-hydroxylated tryptamines and 4-chloroamphetamine utilize the membrane 5-hydroxytryptamine carrier to pass into serotoninergic neurones. The accumulation and deamination of 14C-tryptamine by mouse brain slices or homogenates of rat hypothalamus were not inhibited by cocaine or norzimelidine, a selective inhibitor of the neuronal 5-HT uptake. The prevention by alpha-methyltryptamine (10 mg/kg, intraperitoneally), alpha-ethyltryptamine (20 mg/kg intraperitoneally) and 4-chloroamphetamine (20 mg/kg intraperitoneally) of the irreversible inhibtion of monoamine oxidase by pheniprazine (2.5 mg/kg intraperitoneally) and clorgyline (5 mg/kg intraperitoneally) in serotoninergic synaptosomes from mouse brain was not antagonized by pretreatment of the animals with norzimelidine (20 mg/kg intraperitoneally). The partial preventing effect of alpha-ethyl-4-methyl-m-tyramine (H 75/12)(2 X 50 mg/kg intraperitoneally) was, on the other hand, antagonized by norzimelidine. These results do not support the hypothesis that non-hydroxylated tryptamines and 4-chloroamphetamine are transported by the 5-HT carrier.

Animals↗
PubMed1981

Stimulation of bacterial arylsulfatase activity by arylamines: evidence for substrate activation.

A number of arylamines (including tyramine and tryptamine) increased the in vitro activity of arylsulfatase from Pseudomonas sp. strain C12B. Amino acid analogs of these amines (e.g., tyrosine and tryptophan) failed to exert an effect. Stimulation of activity by tyramine could not be accounted for in terms of sulfotransferase activity for this phenol, and no shift in the pH optimum for the enzyme occurred in the presence of tryptamine. Increased Vmax due to these amines was independent of enzyme concentration but varied significantly with substrate concentration. Evidence is presented which suggests that arylamines enhance arylsulfatase activity by forming a salt linkage with the substrate and rendering it more susceptible to enzymatic and acid-catalyzed hydrolyses. The recrystallized tryptamine salt of the substrate exhibited a reduced affinity for the enzyme but was hydrolyzed more rapidly than the potassium salt, which is normally employed as the assay substrate.

Arylsulfatases↗
PubMed1978

Arylalkylamines in the adrenal medulla.

The trace amines p-tyramine, m-tyramine, tryptamine, and phenylethylamine have been determined in the bovine adrenal medulla and the rat adrenal gland by the mass spectrometric integrated ion current technique, using the corresponding deuterated amines as internal standards. In the bovine adrenal medulla, these amines were present at levels ranging from 21.7 ng/g for tryptamine to 37.3 ng/g for phenylethylamine, while in the rat adrenal, they occurred in amounts ranging from 5.2 ng/g for m-tyramine to 11.4 ng/g for tryptamine. In the rat, intraperitoneal administration of pargyline (100 mg/kg) increased the adrenal levels of each of the trace amines. Adrenaline, noradrenaline, and p-tyramine were significantly depleted by reserpine (3 or 10 mg/kg), but the level of m-tyramine was unaffected. It is suggested that the mode of uptake of the tyramine isomers into the adrenal medullary granules may depend on the position of the bydroxyl group relative to the side chain on the aromatic nucleus.

Adrenal Medulla↗
PubMed1980

The effect of phencyclidine on noradrenaline uptake by bovine chromaffin granules.

The effects of the psychotomimetic drug, phencyclidine, on the reserpine sensitive uptake of (-)noradrenaline, on the reserpine resistant uptake of tryptamine, and on catecholamine release were studied in vitro using bovine chromaffin granules. Phencyclidine inhibited the uptake of (-)noradrenaline and tryptamine in a concentration-dependent manner. It caused 50% inhibition of (-)noradrenaline uptake at 2 X 10(-4)M and of tryptamine uptake at 7 X 10(-4)M. Release of catecholamines was not affected by phencyclidine at 0 degree C and pH 6--8 in concentrations up to 8 X 10(-3)M, whereas at 37 degrees C the drug (4 X 10(-3)M) caused a release that was increased when the pH was raised from 6 to 8. Since the effects of phencyclidine on chromaffin granule uptake and release are observed at high concentrations of the drug only, there is no evidence that these effects are relevant to the in vivo effects of the drug.

Animals↗
PubMed1975

Modification of rat uterine monoamine oxidase activity by steroid hormones.

The monoamine oxidase (MAO) activity in the ovariectomized rat uterus was significantly increased above control levels in animals given testosterone: 33% (P smaller than 0.01) with tryptamine or 34% (P smaller than 0.05) with tyramine as substrate. Activity was also higher in hydrocortisone-treated animals: 30% (P smaller than 0.05) with tyramine or 25% (P smaller than 0.05) with tryptamine as substrate. Progesterone injection increased MAO activity toward tyramine by 20% but towards tryptamine by only 8%. The differences are not statistically significant but are believed to be real since they were reproducible. MAO activity in oestradiol-treated animals was 11% less than in the controls for both substrates. Although they are not significant differences, they were reproducible. No change in MAO activity was observed in the cerebellum, hypothalamus or anterior pituitary of ovariectomized rats after steroid treatment. At oestrus the enzyme activity in the uterus was lower than at dioestrus or prooestrus when beta-phenylethylamine was the substrate. When 5-hydroxytryptamine was used to measure enzyme activity, the same values were found at oestrus, dioestrus and prooestrus. Ovariectomy did not cause any changes in MAO activity in any of the tissues. Effects of the steroids in vivo were probably not due to a direct action on the enzyme since only at high concentration did they have any effect on the mitochondrial enzyme activity of the uterus in vivo.

5-Hydroxytryptophan↗
PubMed2002

In vitro and in vivo assessment of the antioxidant activity of melatonin and related indole derivatives.

Effects of melatonin and some structurally related indole compounds were studied by in vitro methods such as (i) an inhibition of the hyaluronic acid degradation and (ii) a standard lipid peroxidation assay. In vivo approach was based on the alloxan model of hyperglycaemia. Reduction of the viscosity of a hyaluronic acid solution in the reaction mixture was inhibited by tryptamine (91% inhibition), as well as by indole-3-carboxylic acid and indomethacin (80% and 77% inhibition, respectively). Lipid peroxidation with tert-butyl hydroperoxide as a source of radicals was followed by the formation of thiobarbituric acid reactive substances. Tested drugs inhibited lipid peroxidation in the order: tryptamine (59%) > indole-2-carboxylic acid (38%) > indomethacin (26%) > melatonin and indole-3-carboxylic acid (13%). In vivo, alloxan-induced hyperglycaemia was reduced in mice pretreated with drugs tested. The highest protective effect was observed with indomethacin (52% inhibition), followed by tryptamine and melatonin (18% and 16% inhibition, respectively).

Alloxan↗
PubMedDate not supplied

Quantitative autoradiography of [3H]norharman [( 3H]beta-carboline) binding sites in the rat brain.

The anatomical distribution of [3H]norharman binding sites was determined by quantitative autoradiography in rat brain slices. They are enriched in hypothalamic, thalamic, accumbens and amygdaloid nuclei as well as in hippocampal, neocortical and olfactory-related structures. The distribution pattern differs from that of other previously described receptors or binding sites (e.g. monoamine oxidase, benzodiazepine, tryptamine, 5-hydroxytryptamine receptors (5-HT1A, 5-HT1B, 5-HT1C, 5HT2], which suggests that a unique class of [3H]norharman binding sites exists in the rat brain. The findings are consistent with previous experiments which showed high affinity binding sites for [3H]norharman in rat brain membranes (KD 1.552 nM; autoradiography KD 5.5 nM). A correspondence in the displacing activity of drugs was found for both methods (crude membrane fraction: harman much greater than tryptamine much greater than 5-hydroxytryptamine greater than N-methyl-beta-carboline-3-carboxamide (FG 7142) = diazepam; autoradiography: harman much greater than tryptamine much greater than FG 7142 greater than 5-hydroxytryptamine greater than diazepam). Provided that the binding sites represent functional receptors, the present anatomical findings may explain the biological effects of norharman, e. g. pro-conflict behaviour (limbic-hypothalamic structures), tonic-clonic convulsions (limbic-cortical structures) and alterations of locomotor activity (accumbens nucleus).

Alkaloids↗
PubMed1987

Pharmacological characterization of two 5-hydroxytryptamine receptors coupled to adenylate cyclase in guinea pig hippocampal membranes.

Two 5-hydroxytryptamine (5-HT) receptors mediate stimulation of adenylate cyclase activity in membranes of adult guinea pig hippocampus. The two receptors were characterized with agonists and antagonists and with the aid of computerized curve-fitting procedures. Each receptor mediates about 50% of the maximal response to 5-HT. 5-HT is about 10-fold more potent in eliciting response through one cyclase-linked receptor (RH) than the other (RL). The concentrations of 5-HT that elicit half-maximal response through RH and RL are 43 +/- 6 nM and 414 +/- 53 nM, respectively. 5-Methoxytryptamine (5-MeOT) and 5-HT are approximately equipotent at each receptor. The agonists tryptamine and bufotenine are less potent than 5-HT at both receptors, and each is about 50-fold selective for RH. The two receptors are best discriminated by the agonists 5-carboxamidotryptamine (5-CONH2-T) and 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT), both of which are selective for RH. 5-CONH2-T is about 7-fold more potent than 5-HT at RH. The rank order of agonist potencies at RH (5-CONH2-T greater than 8-OH-DPAT = 5-HT = 5-MeOT greater than bufotenine greater than tryptamine) differs from that at RL (5-HT = 5-MeOT greater than bufotenine greater than tryptamine = 5-CONH2-T greater than 8-OH-DPAT). Spiperone acts as a simple competitive antagonist at RH, with a dissociation constant of 20 nM, but it is at least 100-fold less potent as an antagonist at RL. The relatively low affinities of the selective 5-HT antagonists ketanserin and MDL 72222 for RH and RL indicate that neither receptor may be classified as the 5-HT2 or as the 5-HT3 (i.e., peripheral neuronal) type. The characteristics of RH suggest that it is a functional correlate of the 5-HT1A-binding site in brain. RL appears not to correspond to a known 5-HT-binding site, but it may be homologous to receptors that mediate 5-HT-stimulated adenylate cyclase activity in other systems such as infant rat colliculi. RH and RL may also mediate stimulation of adenylate cyclase activity by 5-HT in hippocampal membranes of adult rat.

5-Methoxytryptamine↗
PubMed1978

Serotonin metabolism in patients with carcinoid tumors: incidence of 5-hydroxytryptophan-secreting tumors.

The urinary excretion of 5-hydroxyindoleacetic acid, 5-hydroxytryptophan, serotonin, tryptamine, and tyramine and the serum serotonin concentration were determined in 38 consecutive patients with metastatic carcinoid tumors. Four of the 23 patients with the carcinoid syndrome (15%) had markedly elevated excretion of 5-hydroxytryptophan. None of the patients had markedly elevated excretion of tryptamine or tyramine; a substantial number of patients had moderately low urinary excretion of these amines. All of the patients with the carcinoid syndrome had elevated urinary 5-hydroxyindoleacetic acid excretion; 2 of these patients had normal serum serotonin concentrations, suggesting that quantitative 5-hydroxyindoleacetic acid excretion is the most reliable test for the carcinoid syndrome. Although tryptamine secretion by carcinoid tumors is rare, 5-hydroxytryptophan secretion may be more common than is recognized.

5-Hydroxytryptophan↗
PubMed1987

Ligands which effect human protein C activation by thrombin.

This report documents attempts to mimic the rate enhancement effect of thrombomodulin on human alpha-thrombin-catalyzed activation of human protein C in the absence of exogenous calcium. Specifically the following tryptamine analogs at 1 mM concentration were shown to enhance the protein C activation rate relative to a control with no added effector at pH 8.3 (50 mM Tris-HCl, 0.1 M NaCl, 37 degrees C): serotonin, 1.2; tryptamine, 2.9; 5-fluorotryptamine, 4.4; 6-fluorotryptamine, 7.2. At much higher levels, e.g. 10 mM, all of the above effectors, as well as indole, showed a moderate inhibition of human protein C activation. ATP, a platelet release product, showed a sigmoidal inhibition pattern similar to that found previously for thrombin amidase, clotting, and esterase activity (Conery, B.G., and Berliner, L.J. (1983) Biochemistry 22, 369-375). Overall, the enhancement factors for human alpha-thrombin activation of protein C with the tryptamine analogs described above were remarkable when considering the effect of a simple ligand versus the natural activator, thrombomodulin.

Adenosine Triphosphate↗
PubMed1994

Is it possible to predict the clinical effects of neuroleptics from animal data? Part V: From haloperidol and pipamperone to risperidone.

In 1965 the first study of this series reported different effects of neuroleptics in rats, supporting clinical differences. At the one end, haloperidol presented as a potent and specific antagonist of the psychostimulants amphetamine and apomorphine. Haloperidol-like neuroleptics have marked effects on psychomotor agitation, delusions and hallucinations and bind with high affinity to dopamine-D2 receptors. Pipamperone, at the other end, presented with weak "dopamine" antagonism and more striking tryptamine antagonism. Pipamperone is known to improve disturbed sleep, social withdrawal and other symptoms of chronic schizophrenia in the relative absence of extrapyramidal symptoms. These effects have been attributed to central serotonin-S2 antagonism, on the basis of the clinical effects of ritanserin. As shown by the present analysis of relative tryptamine versus apomorphine antagonism of 57 neuroleptics, in comparison to relative S2 vs. D2 binding, there is a continuity in the series. About 30% of the compounds can be considered to act primarily as serotonin antagonists, but few are markedly more potent than pipamperone. In amphetamine-challenged rats pipamperone-like activity is reflected in preferential inhibition of the excessive oxygen consumption rather than of agitation. Risperidone inhibits oxygen consumption (0.016 mg/kg) at the same dose as haloperidol inhibits agitation. Other low-dose effects of risperidone include reversal of amphetamine-induced withdrawal, antagonism of agitation induced by a sequential tryptamine and apomorphine challenge and LSD-antagonism. In dogs, the antiemetic activity of risperidone is characterized by high oral effectiveness which lasts one day and agrees with pharmacokinetic data when allowance is made for the active metabolite 9-hydroxyrisperidone.(ABSTRACT TRUNCATED AT 250 WORDS)

Amphetamine↗
PubMed1988

Charge transfer complexes of indole:catechol type II.

Charge transfer complexes between tryptamine:epinephrine, tryptamine:isoproterenol, tryptamine:catechol, and indole:catechol were demonstrated spectrophotometrically in aqueous solutions containing 0.1 M HCl. It was possible to make precise measurements and to calculate thermodynamic parameters and molar absorptivities. In general, the equilibrium constant was found to be quite low and ranged from 4.00 +/- 0.04 to 0.30 +/- 0.02 M-1. These interactions are exothermic and have relatively large standard enthalpy and entropy changes (delta Ho values ranged from -7.4 +/- 0.3 to -5.2 +/- 0.4 kcal mol-1; delta So ranged from -25 +/- 5.0 to -16 +/- 1.3 cal K-1 mol-1). The similarity in delta Ho and delta So values for all the combinations indicates a similar interacting system. This result has led us to propose the involvement of the charge transfer effect, induced in the indole:catechol system, in the mechanism occurring in nerve conductions.

Catechols↗
PubMed1977

Monoamine oxidase in rat reticulocytes: subcellular localization and identification of isoenzymes.

After "chemically induced reticulocytosis" in rats by treatment with acetyl-phenylhydrazide, monoamine oxidase (MAO) activities were determined in erythrocyte preparations of these animals. Studies on subcellular fractions obtained by differential centrifugation showed that the enzyme activity of rat reticulocytes is a classical mitochondrial MAO. The patterns of inhibition produced by clorgyline (A-type MAO), deprenil (B-type MAO) and pargyline or tranylcypromine (both types of MAO) in reticulocytes were determined in vitro using tryptamine as a substrate for both types of MAO and phenylethylamine as a substrate for the B-type. The results indicate that both A-type (approximately 75%) and B-type (approximately 25%) MAO are present in rat reticulocytes; while tryptamine was mainly deaminated by the A-type enzyme, both types of MAO were shown to contribute to the deamination of phenylethylamine. These findings were confirmed in investigations on the thermostabilities of the tryptamine and phenylethylamine deaminating activities of rat reticulocyte MAO.

Animals↗
PubMed1989

Binding sites for brain trace amines.

1. Neurochemical, neuropharmacological, and neurophysiological studies suggest that some of the so-called trace amines may have a role in the modulation of neurotransmission. This review examines the possible existence and characterization of brain binding sites for the trace amines. 2. The results of radioligand binding studies carried out so far suggest the existence of tryptamine binding sites that possibly constitute a true functional receptor. This is supported by evidence obtained from the saturation studies, drug-mediated inhibition of binding, and the changes in the number of sites induced by pharmacological and lesion studies. In addition, the existence of a functional tryptamine binding site is supported by the increased neurophysiological responses of tryptamine obtained from the striatum of rat with unilateral substantia nigra lesions. 3. It has been shown that the brain contains saturable binding sites for rho-tyramine that appear to be related to the transport of dopamine into synaptic vesicles. There are, however, some questions with respect to the homogenization technique employed and some inconsistencies with respect to the number of binding sites estimated in neuronal membrane preparations. 4. The existence of rho-octopamine binding sites has been demonstrated in crude membranes obtained from fruitflies but not shown so far in vertebrates. 5. The presence of brain binding sites for beta-phenylethylamine are suggested but they are not so well defined and its physiological implication remains to be elucidated.

Animals↗
PubMed1990

Gas chromatography of tryptophan together with other amino acids in hydrochloric acid hydrolysates.

The classical hydrolysis of proteins with hydrochloric acid using tryptamine [3-(2-aminoethyl)indole] as additive revealed that tryptophan can be measured without destruction together with other amino acids by gas chromatography. An extensive study was made to establish the optimum conditions for protein hydrolysis (time and temperature of hydrolysis, amount of tryptamine) and for the derivatization of amino acids. The amino acid contents (including tryptophan) of standard proteins such as lysozyme, bovine and human albumin, human gamma-globulin, casein and alpha-chymotrypsin and protein matrices (meat and fish meals, sunflower) were determined, after hydrochloric acid hydrolysis (4 h, 145 degree C) in the presence of tryptamine. as N, O, (S)-trifluoroacetyl isobutyl esters with SE-30 as the stationary phase. The reproducibility of the measurements was 4.6% (relative standard deviation) or less.

Amino Acids↗
PubMed1988

Identification of a 5-HT1 recognition site in human brain membranes different from 5-HT1A, 5-HT1B and 5-HT1C sites.

In human caudate and cortex membranes, [3H]serotonin ([3H]5-HT) labels 5-HT1A and 5-HT1C recognition sites which show nanomolar affinity for 8-OH-DPAT (8-hydroxy-2-(di-n-propylamino)-tetralin) and mesulergine respectively, whereas no 5-HT1B binding could be identified. However, the majority of the sites labelled by [3H]5-HT (greater than or equal to 60% in cortex, 90% in caudate) are different from 5-HT1A, 5-HT1B and 5-HT1C sites. Competition experiments were performed in human caudate membranes incubated with [3H]5-HT in the presence of 100 nM 8-OH-DPAT and 100 nM mesulergine. Under those conditions, [3H]5-HT labelled an apparently homogeneous population of 5-HT1-like sites which display nanomolar affinity for tryptamines (5-carboxamido-tryptamine, (5-CT) greater than 5-HT greater than or equal to 5-methoxytryptamine (5-MeOT) greater than tryptamine) and some ergolines (metergoline greater than methysergide). In contrast, these sites showed low affinity for drugs with high affinity and/or selectivity for 5-HT1A (8-OH-DPAT, buspirone), 5-HT1B (21-009, RU 24969), 5-HT1C (mesulergine, mianserin) and 5-HT2 sites (ketanserin, cinanserin). The pharmacological profile of these sites is different from that of 5-HT1A, 5-HT1B, 5-HT1C, 5-HT2 and 5-HT3 sites but is consistent with the pharmacology of a 5-HT1-like receptor. It is very similar to that of the 5-HT1D site recently described in bovine brain by Heuring and Peroutka.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1995

N-acetyltransferase activity in the quail (Coturnix coturnix jap) duodenum.

The activity and kinetics of N-acetyltransferase (NAT) in the quail duodenum were studied by radioenzymatic assay. NAT activity was highest when incubated under 37 degrees C, at pH 5.8 for 15 sec. Of the four substrates tested (tryptamine, 5,6-dihydroxytryptamine, serotonin, and N-acetylserotonin at concentrations of 0.08-4 mM), only tryptamine showed the substrate saturation phenomenon when incubated with the duodenal enzyme and acetyl-14C-coenzyme A. The saturation concentration of tryptamine was about 4 mM. Using the double reciprocal plot and regression equation, the Michaelis constant (Km) and maximal rate (Vmax) of NAT activity were found to be 0.204 mM and 0.917 nmol.mg protein-1.min-1, respectively. Diurnal study demonstrated higher NAT activity at middark (3.7 nmol.mg protein-1.min-1) and lower activity at midlight (2.4 nmol.mg protein-1.min-1), suggesting a circadian rhythm of the enzyme activities in the quail duodenum.

Animals↗
PubMedDate not supplied

Serotonin immunocytochemistry in the adult and developing rat brain: methodological and pharmacological considerations.

An antiserum has been raised in rabbits against serotonin (5-HT) conjugated to the invertebrate protein hemocyanin (HC). This antiserum was characterized with respect to its cross-reactivity with related compounds and its immunocytochemical staining properties in brains of adult and developing rats and in animals pretreated with various pharmacological regimens. When compared to an antiserum raised against 5-HT/bovine serum albumin (BSA) conjugates [59], the 5-HT/HC conjugate elicited a more profound immune response which resulted in the production of a specific, high titer antiserum that could be used directly for immunocytochemistry without removal of antibodies to the invertebrate carrier molecule, HC. Immunoabsorption experiments to assess the specificity of this antiserum demonstrated a small degree of cross-reactivity with dopamine (which was greater than that with norepinephrine or epinephrine). However, no staining of catecholaminergic neurons was found in untreated adult or developing animals, nor in animals pretreated with L-DOPA or L-DOPA + the MAO inhibitor nialamide, indicating that this cross-reactivity is not manifested under normal staining conditions. No cross-reactivity of the 5-HT/HC antiserum was observed for any 5-HT precursors or metabolites tested, although both this antiserum and the 5-HT/BSA antiserum did exhibit a high degree of cross-reactivity to the related indoleamines 5-methoxytryptamine (5-MT) and tryptamine. However, based on the immunocytochemical staining patterns observed, and the fact that both 5-MT and tryptamine are found in very low quantities in the normal rat brain, it appears that 5-HT is the predominant indoleamine stained by both of these antisera in the untreated rat brain. In animals pretreated with L-tryptophan + nialamide, some light staining was found in the dopaminergic A9 and A10 cell groups using either antiserum. However, since this staining was not observed in L-DOPA + nialamide treated animals it is not thought to be due to cross-reactivity with dopamine. Rather, since the staining could be inhibited by pretreatment with the catecholaminergic uptake blocker desmethylimipramine, it is postulated that this effect may be due to either (1) the non-specific uptake of 5-HT or 5-hydroxytryptophan (5-HTP) into the dopaminergic cells of A9 and A10 due to elevated levels of these substances in the dense serotonergic axonal plexus passing through this region or (2) to an increased uptake of circulating L-tryptophan by these A9 and A10 cells followed by conversion of this amino acid to tryptamine by aromatic amine decarboxylase, an enzyme common to both 5-HT and dopaminergic neurons. This latter possibility suggests that caution should be exercised when interpreting immunocytochemical staining patterns obtained in animals pretreated with L-tryptophan + nialamide using 5-HT antisera, since other cross-reactive indoleamines could be elevated by this pharmacological manipulation.

Animals↗