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PubMed1980

Decreased tyramine sensitivity after discontinuation of amitriptyline therapy. An index of pharmacodynamic half-life.

A combined pharmacodynamic and pharmacokinetic approach was made to study the pharmacodynamic half-life (Pd1/2) of amitriptyline (AT). Six depressed patients were treated with 150 mg of amitriptyline as a single oral dose at night for six or more weeks. Decreased tyramine sensitivity (DTS), an index of this drug's pharmacological activity, was determined serially at various intervals after the last dose. Plasma concentrations of AT and nortriptyline (NT) were also estimated at above intervals. It was possible to detect DTS for 228-300 h after the last oral dose and the mean Pd1/2 of this decline of pharmacodynamic effect was observed to be 135 h. However, no measurable amount of AT or NT was present after 84 h and the mean elimination plasma half-life (t1/2) of AT and NT were 37.7 and 38.9 h, respectively. (In this study, pharmacokinetic parameters of NT were directly related with those of AT.) Prolonged pharmacodynamic effect of this drug after discontinuation should be borne in mind in order to avoid drug interactions and autonomic complications, especially after overdosage. Pd1/2, as assessed by DTS, correlated directly with the t1/2 (r = 0.91) and inversely with the plasma clearance rate (r = 0.60) of NT. DTS test can be used as an alternative technique to assess the biological activity of a drug which inhibits noradrenaline reuptake mechanism and/or blocks alpha-adrenoceptors at the peripheral neuronal sites, especially, where facilities to measure plasma concentrations of such drugs are limited.

Adult↗
PubMed1989

[3H]tyramine binding: a comparison with neuronal [3H]dopamine uptake and [3H]mazindol binding processes.

[3H]Spiperone [( 3H]SPI) binding sites in rat or bovine striata have been solubilized using CHAPS or digitonin detergents. Solubilized sites retained the binding characteristics of those in native membrane preparations. The same solubilized material, however, did not bind [3H]tyramine [( 3H]PTA), thus indicating that [3H]PTA binding sites and DA receptors are different chemico-physical entities. In membrane preparations or crude synaptosomes obtained from the c.striatum of neonatally-rendered hypothyroid rats, when central DA-pathways are impaired, both [3H]PTA binding and [3H]DA uptake processes were markedly decreased, with no effect on [3H]mazindol [( 3H]MAZ) binding, compared to euthyroids. Reserpine, a well-known inhibitor of DA-uptake into a variety of secretory vesicles, and a potent in vivo and in vitro inhibitor of [3H]PTA binding, did not affect the [3H]MAZ binding process. This further supported the suggestion that while [3H]PTA binding sites are almost totally associated with the vesicular transporter for DA, [3H]MAZ does label a site involved in the DA-translocation across the neuronal membrane. The latter process seems to be rather insensitive to thyroid hypofunction, when however the intracellular storage of DA might be consistently impaired. In conclusion, PTA might be well exploited as a marker of the DA vesicular transporter through its molecular characterization, whenever possible.

Animals↗
PubMed1993

Potent, extra-channel influence of several calcium-channel modulators on striatal binding of [3H]tyramine.

A number of Ca(2+)-, K(+)-, and Na(+)-channel modulators has been tested with respect to their effects on [3H]tyramine (TY) binding, as a putative marker for the vesicular dopamine (DA) transporter in striatal membrane preparations containing vesicle ghosts. Among organic Ca(2+)-channel modulators, the diphenylalkylamines tested consistently inhibited TY binding: the order of potency was prenylamine > lidoflazine > flunarizine > cinnarizine, with Ki values of 0.1, 0.2, 0.5 and 1.2 microM, respectively. Low (up to 100 nM) concentrations of prenylamine did competitively inhibit TY binding, and higher concentrations provoked a mixed-type inhibition. Furthermore, LIGAND-analysis of competition curves revealed a high- and a low-affinity binding site for prenylamine and flunarizine. The TY binding process was also sensitive to selected K(+)- and Na(+)-channel modulators. Since several Ca(2+)-antagonists are known to affect H(+)-ATPase and the bioenergetics of catecholamine storage vesicles in chromaffin granules, thus affecting monoamine storage, the energy requirements for the formation of the TY/carrier complex were here assessed, assuming similarity between chromaffin granules and synaptic vesicles. TY binding, though not reflecting endovesicle-sequestered TY, was indeed strongly sensitive (with Ki coefficients in the fM or low nM range) to the dissipation of the vesicular transmembrane proton concentration (delta pH), electrical (delta psi), and proton electrochemical (delta microH+) gradients, provoked by a number of specifically targeted agents. It is concluded that Ca(2+)-channel agents of the diphenylalkylamine group may directly affect striatal TY binding due to an extrachannel-regulated competition with TY for the vesicular carrier of DA, as well indirectly, by disruption of the transmembrane energization of the reserpine-sensitive carrier.

Animals↗
PubMed1993

The tyramine binding site in the central nervous system: an overview.

The [3H]Tyramine (TY) binding site is proposed as a high affinity marker of the membrane carrier for dopamine (DA) in synaptic vesicles from DA-rich brain regions. Under precise assay conditions, there is neither a consistent association of TY with the neuronal, cocaine-sensitive DA transporter, nor with mitochondrial or microsomal targets. TY-labeled sites have a high affinity for selected toxins such as the Parkinsonian agent MPP+ (1-methyl-4-phenylpyridinium ion), or drugs such as diphenylalkylamine Ca(2+)-channel antagonists. The MPP+/TY site interaction, which in the striatum leads to depletion of vesicular DA, occurs in dopaminergic as well as in noradrenergic regions, though with different kinetic profiles. TY-labeled carriers for DA and noradrenaline (NA) in respective vesicles seem to be different entities, which might result in a region-specific rate of toxin sequestration and/or release from heterogeneous vesicles. Whereas MPP+ is a potent competitive-type inhibitor of [3H]TY binding, prenylamine-like Ca(2+)-channel antagonists can compete with TY for the vesicle site, in a tetrabenazine- or reserpine-like manner, and also inhibit TY binding thanks to the extra-channel directed impairment of membrane bioenergetics they are proposed to provoke. This follows from the generally-accepted assumption that similar mechanisms are operational for secretory organelles in adrenals and CNS, and from the marked sensitivity of TY binding to miscellaneous energy-disrupting agents.(ABSTRACT TRUNCATED AT 250 WORDS)

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1983

Urinary excretion of O-methylated catecholamines, tyramine and phenyl-ethylamine by volunteers treated with tranylcypromine and CGP 11305 A.

To assess the effect of the new, selective, reversible MAO A inhibitor, CGP 11305 A (4-(5-methoxy-7-bromo-benzofuranyl-2-)piperidine HCl), on MAO A and B activity in man, the daily excretion of total normetanephrine (NMN), metanephrine (MN), 3-methoxytyramine (3-MT) and beta-phenylethylamine (PEA) was measured in the urine of healthy volunteers treated with weekly increasing doses from 40 to 150 mg/d. A similar study was carried out with tranylcypromine in weekly increasing doses from 10 to 25 mg/d. Both compounds increased the excretion of NMN; with CGP 11305 A, a plateau was obtained at 50 mg/d, and tranylcypromine 20 mg was more effective than 10 mg, and was also more active than the highest dose of CGP 11305 A. Increases in MN and 3-MT produced by the latter compound were comparable to that in NMN, whereas tranylcypromine had a biphasic effect on MN excretion, and caused only a small increase in 3-MT excretion. CGP 11305 A up to 150 mg/d did not alter total tyramine excretion, whereas tranylcypromine at 20 mg caused a definite increase. Tranylcypromine led to 4-6 fold increases in PEA output at 20 and 25 mg/d, but not at 10 mg. No such effect could be demonstrated for CGP 11305 A up to 150 mg/d. These results suggest that in man MAO A was inhibited by CGP 11305 A in daily dose of 40 mg or more, whereas it did not affect MAO B at up to 150 mg.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Differences between the catabolism and tumour distribution of intact monoclonal antibody (791T/36) and its Fab/c fragment in mice with tumour xenografts revealed by the use of a residualizing radiolabel (dilactitol-125I-tyramine) and autoradiography.

Radioiodine-labelled 791T/36 monoclonal antibody (mAb) and its Fab/c fragment, consisting of one Fab arm and the Fc portion, have identical whole-body survival curves in BALB/c mice (t1/2 = 3.75 days). Therefore, these two forms of this antibody provide a suitable model for studying the role of valency in the targeting efficiency of antibodies to tumours in vivo. 791/T36 antibody and its Fab/c fragment were labelled either by direct iodination using the iodogen method (125I) or by dilactitol-125I-tyramine (125I-DLT), a residualizing label, which accumulates in the cells involved in degradation of the carrier protein. In tumour-bearing nude mice, the percentage of injected dose of mAb or Fab/c fragment reaching the specific 791T tumour was similar, and these proteins appeared to be catabolized at a similar rate in this tissue. mAb, but not the Fab/c fragment, was found to be very actively catabolized by the liver and spleen of tumour-bearing mice compared to control nude mice, this probably resulting from clearance of immune complexes. This effect was most pronounced when the mAb was labelled with 125I-DLT, the percentage of injected dose of mAb reaching the spleen and liver being higher than the percentage of injected dose reaching the tumour. This effect was not seen with the Fab/c fragment. Autoradiographic studies on tumour sections, which exhibit antigenic sites throughout the tumour mass, showed that the Fab/c fragment was already homogeneously distributed in the tumour 12 h after injection whereas the whole antibody was mainly localized at the periphery of the tumour. Those results suggest a "binding site barrier" effect. Overall, these results indicate that the highest valency and affinity may not be the optimal choice for mAb to be used for therapeutic purposes.

Animals↗
PubMed1979

Effects of thyroidectomy on monoamine oxidase activities toward tyramine and serotonin in the circumventricular nuclei of the rat.

Following thyroidectomy, monoamine oxidase (MAO) activities toward tyramine decreased significantly by 20% in the nucleus periventricularis and the nucleus arcuatus among the 3 hypothalamic nuclei of the rat, while MAO activity toward serotonin decreased significantly by 10% only in the nucleus periventricularis. It is suggested that thyroidectomy induced selective changes on the multiple forms of MAO in the discrete circumventricular nuclei.

Animals↗
PubMed1992

Tyramine content of preserved and fermented foods or condiments of Far Eastern cuisine.

The tyramine content of foodstuffs typical of the Far East was analysed: the items included fermented food and condiments as well as seven menus from different Far Eastern restaurants. The results of the present analysis extend to Far Eastern foods our previous conclusion that no severe dietary restrictions are needed in patients treated with moclobemide, a novel RIMA anti-depressant.

Asia↗
PubMed2002

Stress response in Drosophila melanogaster strain inactive with decreased tyramine and octopamine contents.

Juvenile hormone hydrolysis, tyrosine decarboxylase activity, dopamine content and fitness (viability and fertility) were studied under normal and stress conditions in the adults of Drosophila melanogaster inactive strain carrying a mutation that decreases tyrosine decarboxylase activity and results in the lower contents of tyramine and octopamine. A sexual dimorphism of tyrosine decarboxylase activity, dopamine level and survival under heat stress in inactive flies was found. inactive adults showed higher dopamine levels and lower survival levels under heat stress as compared to wild type (Canton S) adults. Juvenile hormone degradation is decreased in young and increased in mature inactive females as compared to wild type. Fertility of the inactive strain did not differ from that of wild type strain under normal conditions, but after heat exposure the dynamics of its restoration was different. inactive females were found to develop the stress reaction, with juvenile hormone degradation, tyrosine decarboxylase activity, dopamine content and fertility levels used as the reaction indicators.

Animals↗
PubMed1999

SV40 large T-antigen and human pleural mesothelioma. Screening by polymerase chain reaction and tyramine-amplified immunohistochemistry.

DNA-like sequences of the p53 and pRB-inactivating simian virus 40 large T-antigen (SV40 LTag) have recently been found in mesotheliomas in the United States and several European countries. Nuclear expression of SV40 LTag, possibly in concert with detectable telomerase activity, could be responsible for immortalisation of (pre)malignant clones, as suggested by the mesothelioma-specific latency period. Depending on the antibody used, different results have been observed regarding the subcellular expression of SV40 LTag in mesotheliomas with SV40 LTag-like DNA sequences. In this study, we screened 28 Belgian mesothelioma tumour samples for the presence of SV40 LTag-like DNA and its gene product by polymerase chain reaction amplification, using the SV.for3/SV.rev primer set, and by tyramine-amplified immunohistochemistry, using the pAb419 and the pAb101 SV40 LTag antibodies. Amplicons were found in 13 of the 28 (46%) mesotheliomas. Cytoplasmic, but no nuclear, staining was found in 10 of these 13 cases. Although our study confirms the presence of SV40 LTag-like DNA sequences in Belgian mesotheliomas, we did not detect nuclear expression of the viral oncoprotein, which makes a pathogenic role of SV40 LTag in mesothelioma carcinogenesis questionable.

Adult↗
PubMed1976

Evaluation of the antinociceptive effects of 4, alpha-dimethyl-m-tyramine (H 77/77) in the rat.

4, alpha-Dimethyl-m-tyramine (H 77/77) has been shown to induce dose dependently antinociceptive activity against 3 parameters: (1) the motor (M), (2) the vocalisation during stimulation (V) and (3) the vocalisation after withdrawal of stimulation (VA) responses. The effect of H 77/77 upon the V and VA pain responses was abolished or reduced by prior treatment with phenoxybenzamine, chlorpromazine, H 44/68, FLA 63, reserpine and protriptyline, and was potentiated by atropine sulphate. It is suggested that H 77/77 may exert is inhibitory effect on painful stimulation predominantly by inhibiting spinal sensory input.

Amines↗
PubMed1980

Antagonism of an indirectly acting agonist: block by propranolol and sotalol of the action of tyramine on rat heart.

Some agonists act indirectly in the sense that they cause the release of a second substance that brings about the response finally observed. An antagonist which competitively inhibits the action of the intermediate substance will also reduce the response to the indirectly acting agonist, provided that the receptors are freely accessible. A simple mass-law model for indirect antagonism of this kind is presented, and its predictions are compared with the results obtained in an experimental study of the influence of propranolol and sotalol on the inotropic response of isolated rat atria to tyramine. While there is reasonable qualitative agreement, the fit is not exact and reasons for this are discussed.

Animals↗
PubMed1982

A possible mechanism of the tyramine-induced head-twitch response.

The effects of monoaminergic drugs on the head-twitch response (HTR) induced by intracerebroventricular (i.c.v.) injection of tyramine (TyA) in mice pretreated with safrazine, a monoamine oxidase inhibitor, were compared with effects on the response induced by the i.c.v. injection of serotonin (5-HT) in safrazine-pretreated mice. The HTR induced by both TyA and 5-HT were suppressed by i.p. injection of p-chlorophenylalanine. Chlorimipramine enhanced the 5-HT response but not the TyA response. Dimethothiazine, a serotonergic blocker, reduced both the TyA and 5-HT responses. The i.c.v. injection of p-chlorophenylalanine methylester resulted in a reduction of the TyA response but not of the 5-HT response. The i.c.v. injection of 5,6-dihydroxytryptamine (5,6 DHT) 1 day before the test suppressed the TyA response but enhanced the 5-HT response. The i.c.v. injection of noradrenaline reduced both the TyA and 5-HT responses. The i.c.v. injection of 6-hydroxydopamine, and i.p. injection of alpha-methyl-p-tyrosine and tolazoline accelerated the TyA response. These results suggest that the TyA response may be based on the release of endogenous 5-HT and can be suppressed by the catecholaminergic system.

5,6-Dihydroxytryptamine↗
PubMed1985

Metabolism of [125I]tyramine cellobiose-labeled low density lipoproteins in squirrel monkeys.

Low density lipoproteins labeled with [125I]tyramine cellobiose ([125I]TC-LDL) were removed from the circulation of squirrel monkeys at a similar but slightly slower rate than LDLs labeled with 125I, [125I]hydroxyphenyl propionic acid, or [3H]leucine. After the simultaneous injection of [125I]TC-LDL and [131I]LDL labeled with 131ICl, the 125I was also removed at a slightly slower rate than 131I. Most of the radioactivity was retained in tissues and not excreted during the 24 h after injection of [125I]TC-LDL. This finding supports the claim of Pittman et al. [18] that [125I]TC-LDL can be used to determine the irreversible uptake of LDL by different tissues. The liver cleared more LDL than any other organ, but the adrenals and ovaries were more active per gram. Trichloroacetic acid (TCA) precipitated more than 80% of the radioactivity in the tissues that had low 125I uptake, but only about 50% of the 125I in more active tissues (liver, adrenals, ovaries, and spleen). Only a small percentage of 125I in urine and bile was TCA-precipitable. In the dual label experiment with [125I]TC-LDL and [131I]LDL there was a selective retention of 125I in samples from liver, spleen, adrenals, and, perhaps testes, and an almost complete selectivity for 125I in bile and feces. The aortic intima plus inner media (AIM) cleared much less LDL than other tissues, but the uptake by the entire AIM was proportional to the cholesterol concentration and weight of the total AIM. There was, however, no correlation between either of the latter two measurements and the uptake of LDL per gram of AIM. The concentration of LDL apolipoprotein in the AIM determined by immunoelectrophoresis did not correlate significantly with LDL uptake per gram. Both the amounts of LDL apolipoprotein present and labeled LDL taken up by the AIM depended on the weight of the sample, and perhaps on the weight of intima in the sample.

Animals↗
PubMed1989

Quantitation of IgG antibody to Streptococcus pneumoniae vaccine by ELISA and FAST-ELISA using tyraminated antigen.

We examined two ELISA methods for measuring antibodies to Streptococcus pneumoniae using tyraminated S. pneumoniae polysaccharide types 3, 7N, 9F and 14 as antigens. The ELISA has the usual format with a relatively long incubation time whereas the FAST-ELISA has a short incubation time and employs a different solid-phase configuration. We showed that both techniques can be used for the detection of antibodies to S. pneumoniae polysaccharides. Although its analytical sensitivity is about 1/10 of that of the ELISA, the FAST-ELISA is sufficiently sensitive to distinguish protective from unprotective levels of antibodies to the types of S. pneumoniae studied. In studying pre- and post-immunization response, we showed that type 3 is the most immunogenic.

Antibodies, Bacterial↗
PubMed1986

The concentration in brain of octopamine and tyramine after portal-systemic bypass in rats: neuroamine concentrations determined simultaneously by methane chemical ionization gas chromatography mass spectrometry.

The concentration in brain of both octopamine (OCT) and tyramine (TYR) was significantly increased in rats 8 weeks after portal-systemic bypass. This suggests that the increase in OCT is secondary to increased decarboxylation of tyrosine to TYR. However, the role these neuroamines, particularly OCT, play in the development of hepatic encephalopathy remains controversial.

2-Hydroxyphenethylamine↗
PubMed1987

Phenylethylamine metabolism to tyramine by postmortem human brain preparations.

Human brain preparations obtained from either the putamen, thalamus, hippocampus or lateral occipital gyrus p-hydroxylate phenylethylamine to tyramine, a reaction carried out by a microsomal (100,000 xg pellet) membrane bound, NADPH-requiring enzyme. This is a minor metabolic pathway occurring in chronic psychiatric patients, as well as in age-comparable controls.

Aged↗
PubMed1988

Pressor responses to tyramine and norepinephrine after subchronic administration of fluoxetine to man.

The effects of subchronic, oral administration of fluoxetine (60 mg daily for 45 days) were studied in three healthy male volunteers. The pressor responses to intravenous bolus tyramine injections or norepinephrine infusions were assessed during the one-week placebo period, periodically after daily fluoxetine dosing, and then for 11 days post-fluoxetine dosing. The dose-pressor responses, determined from the incremental elevation of systolic blood pressure, were unchanged in each of the three dosing intervals. These results indicate that fluoxetine does not significantly impair the catecholamine uptake mechanism in the peripheral adrenergic neuron on acute or subchronic dosing, nor is any rebound-increased sensitivity evident after subchronic administration. Further, fluoxetine does not appear to demonstrate peripheral alpha-adrenolytic properties in man.

Administration, Oral↗