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PubMed1988

Tyramine sulfate excretion may be a better predictor of antidepressant response than monoamine oxidase activity.

The tyramine sulfate excretion test was performed on 62 nonmelancholic depressed outpatients who then took part in a 6-week double-blind trial comparing imipramine, phenelzine, and placebo. In a double-blind design, nonresponders were switched to one of the active medications. Tyramine sulfate excretion failed to differentiate response from nonresponse to placebo. By contrast, phenelzine responders excreted significantly less tyramine sulfate than did phenelzine nonresponders, while there was a trend in the same direction for imipramine-treated patients. The presence of only eight phenelzine nonresponders dictates caution in interpreting these results. Baseline monoamine oxidase (MAO) activity did not distinguish responders from nonresponders or correlate with tyramine sulfate excretion. Although males had significantly lower MAO activity than females, controlling for sex did not alter these negative findings. These results fail to confirm a previous report of a significant correlation between MAO activity and treatment response in older, mainly melancholic patients.

Adult↗

PubMed1996

Histamine and tyramine production by bacteria from meat products.

A series of 94 strains of lactic acid bacteria and Micrococcaceae were tested for their ability to decarboxylate histidine and tyrosine in a laboratory medium. Histamine and tyramine were quantified by using a fluorimetric and a HPLC method. There was no significant difference between the results obtained with either method. Among the strains tested, only three released histamine. On the other hand, all the strains of Carnobacterium produced high concentrations of tyramine (2193 micrograms/ml). Some strains of Lactobacillus curvatus and also Lactobacillus plantarum showed tyramine production. Micrococcaceae and Lactobacillus sake did not produce tyramine.

Chromatography, High Pressure Liquid↗

PubMed1982

Analysis of the effects of noradrenaline and tyramine in isolated middle cerebral and femoral arteries of cat.

1. Tyramine and noradrenaline (NA) caused dose-dependent contractions in middle cerebral and femoral arteries of cat, which were decreased by phentolamine. 2. Gangliectomy increased the contraction evoked by NA in brain arteries. 3. Reserpine pretreatment and/or gangliectomy reduced the contraction caused by tyramine, the maximal responses being unmodified in the cerebral vessels. 4. Tyramine induced Ca2+-dependent tritium release from brain and femoral arteries, which was reduced by reserpine pretreatment and/or gangliectomy. 5. These data suggest that tyramine has a direct component, apart from an indirect one, in brain arteries. The mechanisms by which NA induces slight contraction in them, including the role of Ca2+, are postulated.

Animals↗

PubMed1984

Effects of nialamide on responses of dog isolated arteries to tyramine and transmural electrical stimulation.

In dog mesenteric arteries, nialamide (10(-5) M), a monoamine oxidase inhibitor, potentiated contractile response to tyramine but not to noradrenaline or transmural electrical stimulation (TES). Bretylium, desipramine or prior reserpinization inhibited the potentiating action of nialamide on the tyramine-induced contraction. Contractions induced by octopamine were not reduced by prior reserpinization. In the coronary artery, relaxing responses to tyramine were potentiated but those to noradrenaline and TES were not potentiated by nialamide. In the cerebral artery, nialamide failed to potentiate tyramine-induced contraction. The functional role of intraneuronal monoamine oxidase in sympathomimetic effects is discussed.

Animals↗

PubMed1994

Altered alpha-adrenergic responses of vas deferens to noradrenaline and tyramine from rats with short- and long-term alloxan diabetes.

1. Functional and morphological abnormalities in vas deferens have been reported by both experimental and clinical studies as a cause of genital function abnormalities in diabetic males. 2. In the present study, contractile effects of noradrenaline and tyramine in isolated vas deferens from rats with short- and long-term alloxan diabetes were investigated by comparing with those from control rats. For this purpose, intrinsic activities (alpha E value) and apparent affinity constants (pD2 value) for contractile effects of noradrenaline and tyramine in the isolated rat vas deferens were calculated in normal rats and rats with short- and long-term alloxan diabetes. 3. Apparent affinity constants for contractile effects of noradrenaline in the isolated rat vas deferens were increased depending on both short- and long-term alloxan diabetes. By contrast, apparent affinity constants for contractile effects of tyramine in the isolated rat vas deferens were attenuated due to both short- and long-term alloxan diabetes. Intrinsic activities for both noradrenaline- and tyramine-induced contractions of rat vas deferens, however, were increased due to short-term diabetes and decreased due to long-term diabetes. 4. Experimental findings obtained in this study indicate that vas deferens preparations from rats with short- and long-term alloxan-induced diabetes exhibit altered alpha-adrenergic responsiveness depending on time elapsed. While short-term alloxan diabetes causes enhanced alpha-adrenergic responses in the rat vas deferens, the long-term diabetes decreases the responses in this tissue.

Adrenergic alpha-Agonists↗

PubMed1984

Measurement of tyramine in human plasma, utilising ion-pair extraction and high-performance liquid chromatography with amperometric detection.

An assay for plasma tyramine has been developed which uses ion-pair extraction, reversed-phase ion-pair high-performance liquid chromatography and amperometric detection. Tritiated tyramine is used as the internal standard. The method can measure down to 0.5 ng/ml of tyramine in 1 ml of human plasma and is thus suitable for monoamine oxidase inhibitor studies involving oral dosing with tyramine.

Allylamine↗

PubMed1984

Is tyramine a specific inhibitor of proctolin?

Samples of tyramine purchased from six different manufacturers were tested for their effectiveness and specificity in blocking proctolin- and neurally-evoked contractions of the superior longitudinal muscles of the locust (Locusta migratoria) rectum. It was found that tyramine was neither specific (in that it also blocked glutamatergic responses) nor consistent in its action, as samples purchased from different manufacturers gave a range of different results. The venom of the wasp Philanthus triangulum was used to block glutamatergic responses to enable proctolinergic responses to be studied in isolation. Thin layer chromatography was performed to determine the purity of the tyramine samples but no correlation could be made between purity and efficacy or specificity of proctolinergic antagonism. It is concluded that, due to the inconsistency and non-specificity of its action, tyramine should not be used as an antagonist for proctolin.

Animals↗

PubMed1990

Tyramine antagonizes proctolin-induced contraction of the isolated foregut of the locust Schistocerca gregaria by an interaction with octopamine2 receptors.

1. Octopamine (OA) (10(-7)-10(-5) M) relaxed isolated foreguts. Tyramine mimicked the effects of OA but was 64x less potent. 2. Proctolin (10(-8) M to 10(-6) M) induced contraction of isolated foreguts was antagonised non competitively by tyramine. 3. Mianserin (10(-6) M) was a non competitive antagonist of relaxation caused by tyramine but was without effect on proctolin induced contraction. 4. Caffeine (1 microM and 2 microM) caused non competitive inhibition of proctolin-induced tissue contraction. 5. It is concluded that tyramine antagonises proctolin-induced contraction of the foregut by activating an adenylate cyclase-linked OA2 receptor.

Animals↗

PubMed1995

The tyramine-labelled vesicular transporter for dopamine: a putative target of pesticides and neurotoxins.

This study defined the ability of a large sample of heterogeneous pesticides and neurotoxins to interact with the [3H]tyramine-labelled vesicular transporter of dopamine in rat striatum. Botanical (with rotenone as the most potent), and organochlorine (Kepone) insecticides, as well as fungicides (Zineb), as a whole, consistently inhibited [3H]tyramine binding, with Ki values ranging from 5 nM to 10 microM. ATP/Mg(2+)-dependent [3H]tyramine uptake to purified striatal synaptic vesicles was also inhibited by rotenone. Organophosphate and carbamate insecticides, and miscellaneous herbicides poorly antagonized [3H]tyramine binding, yielding Ki values exceeding 10 microM. Several, though not all, of the best recognized central neurotoxins tested were major binding antagonists. Their rank order of potency was 1-methyl-4-phenylpyridinium ion (MPP+) > trimethyltin > or = 6-hydroxydopamine > N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4) > 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), with Ki values ranging from 35 nM to 3 microM. Overall, the potent interaction of selected pesticides and chemicals with the vesicular transporter for dopamine, although, by itself, not synonymous with neurotoxicity, would argue for a likely impairment of transmitter homeostasis, or the putative formation of neurodegenerative toxin pools.

Animals↗

PubMed1984

High-performance liquid chromatography with amperometric determination of plasma tyramine.

A method for the measurement of tyramine in human plasma is described. It is based on tetraphenylboron ion-pair extraction and reversed-phase ion-pairing liquid chromatography with amperometric detection. Tyramine can be reliably measured in the range 5-200 ng/ml with an absolute limit of detection of 0.50 ng/ml at a signal-to-noise ratio of 2.0. Correction for variable recovery is made by using a tritiated tyramine internal standard. This assay is suitable for studies on the bioavailability of ingested tyramine and should thus have a role in the development of safer monoamine oxidase inhibitor drugs.

Biological Availability↗

PubMed2002

Limited potentiation of blood pressure response to oral tyramine by brain-selective monoamine oxidase A-B inhibitor, TV-3326 in conscious rabbits.

TV-3326 is a novel cholinesterase inhibitor that produces irreversible brain-selective inhibition of monoamine oxidase (MAO)-A and B and has antidepressant-like activity in rats after chronic oral administration. This study determined whether TV-3326 would cause less potentiation than other irreversible MAO-inhibitors of the blood pressure (BP) response to oral tyramine in conscious rabbits. Dose-response curves were established for the increase in BP induced by tyramine (5-200 mg/kg) administered orally via a naso-pharyngeal tube. From these, the dose that increased BP by 30 mmHg (ED(30)) was computed for each rabbit before and after oral administration of clorgyline, 1 mg/kg for one week, tranylcypromine 10 mg/kg, once, moclobemide, 20 mg/kg 3 times and TV-3326, 26 mg/kg for 2 weeks. Clorgyline, tranylcypromine and TV-3326 inhibited brain MAO-A by 90%; the former two inhibited intestinal MAO-A by 85-97% but TV-3326 had no effect. Tranylcypromine and clorgyline produced 6 and 20-fold increases in the pressor response to tyramine while TV-3326, like moclobemide, only potentiated it 2-fold. If TV-3326 is found to produce as little potentiation of the tyramine response in human subjects, it may be a potentially useful therapeutic agent for the treatment of Alzheimer's disease with depression.

2-Hydroxyphenethylamine↗

PubMed1999

The trace amine tyramine is essential for sensitization to cocaine in Drosophila.

BACKGROUND: Sensitization to psychostimulant drugs of abuse is thought to be an important aspect of human addiction, yet how it develops is still unclear. The development of sensitization to cocaine in the fruit fly Drosophila melanogaster is strikingly similar to that observed in vertebrates. By taking advantage of the powerful genetic approaches that are possible in Drosophila, we are able to identify and characterize mutants that fail to develop sensitization. RESULTS: We found that the Drosophila mutant inactive (iav) failed to become sensitized to cocaine. Mutant flies had reduced amounts of the trace amine tyramine in the brain because of reduced activity of the enzyme tyrosine decarboxylase (TDC), which converts tyrosine to tyramine. Furthermore, cocaine exposure induced TDC enzyme activity in a time-dependent manner that paralleled the development of behavioral sensitization. The sensitization failure of iav flies could be rescued by feeding the flies with tyramine; other biogenic amines or amine precursors did not have the same effect. CONCLUSIONS: These results indicate an essential role for tyramine in cocaine sensitization in Drosophila.

Animals↗

PubMed1994

Kinetics and metabolism of p-tyramine during monoamine oxidase inhibition by mofegiline.

The effects of monoamine oxidase B (MAO-B) inhibition by mofegiline on the pharmacokinetics of p-tyramine and its major metabolite, p-hydroxyphenylacetic acid, were investigated in 24 healthy male volunteers. p-Tyramine doses were administered before and after a 14-day treatment period of 1, 12, or 24 mg mofegiline or placebo. Normalized p-tyramine for area under the plasma concentration-time curve after treatment were not significantly different from their respective before-treatment values for any of the dose groups. The relative bioavailability of p-tyramine after treatment was not significantly different from before treatment, although a tendency to a greater bioavailability was seen with the 12 and 24 mg doses. There were no significant differences between pharmacokinetic parameters for p-hydroxyphenylacetic acid. The data suggest that mofegiline maintains its selectivity for MAO-B in the intestine and liver at doses up to and including 24 mg. Therefore these doses would not be expected to be associated with the hypertensive crises normally associated with the "cheese effect."

Adult↗

PubMed1997

Effects of physico-chemical factors influencing tyramine production by Carnobacterium divergens.

Tyramine production by a strain of Carnobacterium divergens was tested in relation to different conditions of pH, temperature, glucose, oxygen availability, potassium nitrate and sodium chloride content, using a combination of a Doehlert and Plackett-Burman experimental design. A second degree polynomial model was chosen to describe tyramine production which was quantified by high performance liquid chromatography. Maximal tyramine production occurred during the stationary phase in acidic conditions obtained by low initial pH (< 5) or addition of glucose (0.6%) to the medium. Production was slower at 5 degrees C than at 23 degrees C and 10% sodium chloride inhibited this production. However, the formation of tyramine was not affected by the presence of potassium nitrate or oxygen availability.

Bacteriological Techniques↗

PubMed1997

Evaluation of three decarboxylating agar media to detect histamine and tyramine-producing bacteria in ripened sausages.

Histidine- and tyrosine-decarboxylase activity of 175 strains of bacteria isolated from eight retail samples of Spanish ripened sausages was tested in three decarboxylating agars (Niven medium, Joosten and Northolt medium and modified decarboxylating agar of Maijala) and confirmed by an enzymic method (histamine) and thin-layer chromatography (tyramine). Enterobacteria and pseudomonads showed the highest percentage of positive responses to histamine and tyramine in the three decarboxylating agars, but only enterobacteria were subsequently confirmed as histamine-producing. Confirmed tyramine-producing strains were all identified as enterococci or lactic acid bacteria. The medium described by Joosten and Northolt was more sensitive and faster at detecting tyramine-producing microorganisms. However, all three media failed to detect one histamine-positive strain of lactic acid bacteria used as a control.

Agar↗

PubMedDate not supplied

Pressor response to intravenous tyramine in healthy subjects after safinamide, a novel neuroprotectant with selective, reversible monoamine oxidase B inhibition.

Safinamide is a novel neuroprotectant combining sodium and calcium channel blocking properties with selective, reversible monoamine oxidase type B (MAO B) inhibition. Phase 1 studies have demonstrated that in healthy volunteers, the ED50 (a dose that inhibits enzyme activity by 50% in 50% of treated subjects) for MAO B inhibition is 87.5 microg/kg/day orally, and that no MAO A inhibition occurs after 10-mg/kg oral dosing. To assess the risk of inducing the "cheese effect," the effect of safinamide and placebo on the pressor response to tyramine was investigated in a group of healthy male volunteers. The study was an open, single-dose placebo-controlled trial with the 2 treatments in sequence. An increase of 30 mm Hg systolic blood pressure was obtained by intravenous tyramine administered by 0.5-mg incremental boluses injected at 15-minute intervals. The amount of tyramine necessary to achieve such a blood pressure increase was the same after the safinamide 2-mg/kg oral load compared with placebo. These results suggest that dietary restrictions for food with high tyramine content should not be required under safinamide treatment.

Adult↗

PubMed2005

Wound-inducible biosynthesis of phytoalexin hydroxycinnamic acid amides of tyramine in tryptophan and tyrosine decarboxylase transgenic tobacco lines.

The wound-activated biosynthesis of phytoalexin hydroxycinnamic acid amides of tyramine was compared in untransformed and transgenic tobacco (Nicotiana tabacum) lines that express tryptophan decarboxylase (TDC), tyrosine decarboxylase (TYDC), or both activities. Transgenic in vitro-grown tobacco lines expressing TDC activity accumulated high levels of tryptamine but not hydroxycinnamic amides of tryptamine. In contrast, transgenic tobacco lines expressing TYDC accumulated tyramine as well as p-coumaroyltyramine and feruloyltyramine. The MeOH-soluble and cell wall fractions showed higher concentrations of wound-inducible p-coumaroyltyramine and feruloyltyramine, especially at and around wound sites, in TYDC and TDC xTYDC tobacco lines compared to wild-type or TDC lines. All the enzymes involved in the biosynthesis of hydroxycinnamic acid amides of tyramine were found to be similarly wound inducible in all tobacco genotypes investigated. These results provide experimental evidence that, under some circumstances, TYDC activity can exert a rate-limiting control over the carbon flux allocated to the biosynthesis of hydroxycinnamic acid amides of tyramine.

Amides↗

PubMed1981

Effects of caroxazone, a reversible monoamine oxidase inhibitor, on the pressor response to intravenous tyramine in man.

1 Caroxazone is a new antidepressant drug with reversible MAO-inhibitory activity. 2 The pressor effect of intravenously injected tyramine has been evaluated in six male healthy volunteers before, during oral treatment with caroxazone 200 mg three times daily and at different time intervals after discontinuation of treatment. 3 Caroxazone produces a moderate tyramine supersensitivity. 4 The reversibility of MAO-inhibition produced by caroxazone is clearly reflected by the time-course of tyramine supersensitivity. In fact, tyramine potentiation does not accumulate with caroxazone cumulative dose, while it is correlated to drug plasma levels and disappears rapidly (half-life 1.5 days) upon discontinuation of treatment. 5 caroxazone seems to be safer and more manageable than all other clinically available MAO-inhibitors which produce irreversible inactivation of MAO.

Adult↗