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PubMed2005

Immunocytochemical identification of neuroactive substances in the antennal lobe of the male silkworm moth Bombyx mori.

As a first step towards understanding the functional role of neuroactive substances in the first olfactory center of the male silkworm moth Bombyx mori, we carried out an immunocytochemical identification of antennal lobe neurons. Antibodies against gamma-aminobutyric acid (GABA), FMRFamide, serotonin, tyramine and histamine were applied to detect their existence in the antennal lobe. In the present immunocytochemical study, we clarified four antenno-cerebral tracts from their origin and projection pathways to the protocerebrum, and revealed the following immunoreactive cellular organization in the antennal lobe. 1) Local interneurons with cell bodies in the lateral cell cluster showed GABA, FMRFamide and tyramine immunoreactivity. 2) Projection neurons passing through the middle antenno-cerebral tract with cell bodies in the lateral cell cluster showed GABA and FMRFamide immunoreactivity. Projection neurons passing through the outer antenno-cerebral tract with cell bodies in the lateral cell cluster showed FMRFamide immunoreactivity. 3) Centrifugal neurons passing through the inner antenno-cerebral tract b with cell bodies located outside the antennal lobe showed serotonin and tyramine immunoreactivity. Our results revealed basic distribution patterns of neuroactive substances in the antennal lobe and indicated that each projection pathway from the antennal lobe to the protocerebrum contains specific combination of neuroactive substances.

Animals↗
PubMed1986

Effects of cholinergic and adrenergic nerve stimulations on amylase release from superfused small segment of rat parotid gland.

The effects of the cholinergic and adrenergic nerve stimulations on amylase release from the segment isolated from the rat parotid gland were investigated, employing the combined techniques of electrical field stimulation (FS) and tyramine application with automated fluorescence method for measuring amylase. The maximum amylase release in response to FS for a short period (1 min) was attained at 16 Hz frequency, 2 ms pulse width and 8 V strength stimulation in the absence of any autonomic antagonist. Periodic short-lasting FS using these parameters at intervals of about 15 min could reproduce similar sizes of amylase release for about 2 h. Continuous long-lasting FS (3 V, 2 ms, 16 Hz) caused a transient sharp increase in amylase release followed by a sustained one. The FS-evoked amylase release was completely abolished by tetrodotoxin (TTX) (10(-7) g/ml) and markedly reduced by atropine (7 X 10(-6) M) or by propranolol (10(-5) M), while it was scarcely affected by hexamethonium (3 X 10(-4) M) and phentolamine (10(-5) M). The maximum stimulus frequency of short-lasting FS for amylase release in the presence of propranolol was similar to that (16 Hz) in the control, but it was higher (32 Hz) in the presence of atropine. Reduced response in amylase release to FS by propranolol was completely restored by the superimposed addition of dibutyryl cyclic AMP (10(-4) M). Application of tyramine (5 X 10(-4) M) evoked amylase release in the presence of atropine, which was blocked mostly by propranolol and partly by phentolamine, while tyramine was ineffective in the tissue segment from rats pretreated with 6-hydroxydopamine. From these results the following were suggested; that the intrinsic cholinergic neurotransmitter activates a muscarinic receptor of the acinar cell, while the adrenergic neurotransmitter stimulates mainly a beta-adrenergic and partly an alpha-adrenergic receptor, resulting in amylase release.

Amylases↗
PubMed1989

Effect of ketanserin and prazosin on blood pressure and cardiovascular reactivity to vasopressor agents during the development of two kidney-two clip renal hypertension in the conscious rat.

The present experiment was performed in order to evaluate some of the actions of ketanserin, a blocking agent active at the serotonin 2 (S2) receptors. Male rats were divided into: 1. Two kidney-two clip (2K-2C) renal hypertensive: a silver clip (0.25 mm width) was placed in both renal arteries. 2. Sham-operated: a similar operation without placing the clip was performed. Blood pressure (BP), heart rate and pressor responses to tyramine, angiotensin II and norepinephrine (NE), and the hypotensive effect of prazosin (Pz) and ketanserin (Kt) were recorded in the conscious animals 8 weeks later. Results showed that Pz produced a similar decrease in BP in hypertensive and sham animals while Kt lowered BP much more in hypertensive than in normotensive rats. Prazosin abolished the pressor response to tyramine while ketanserin only diminished tyramine effect. Both hypotensive agents shifted the dose-response curve to NE to the right. Present data have shown that ketanserin and prazosin are effective hypotensive agents in 2K - 2C renovascular hypertension in the rat. They also suggest that both hypotensive compounds have an alpha 1-blocking effect, somehow they seem to have some differences in their pattern of pharmacological action.

Adrenergic alpha-Antagonists↗
PubMed2003

A double-blind, placebo-controlled trial of the safety and efficacy of selegiline transdermal system without dietary restrictions in patients with major depressive disorder.

BACKGROUND: The monoamine oxidase (MAO) inhibitor selegiline has demonstrated antidepressant efficacy superior to placebo. A selegiline transdermal system (STS) has been developed with unique pharmacokinetic and pharmacodynamic properties that allow inhibition of central nervous system MAO-A and MAO-B enzymes while substantially avoiding inhibition of intestinal and liver MAO-A enzyme. This novel transdermal system provides targeted MAO inhibition without clinically significant increases in sensitivity to dietary tyramine. We investigated the safety and efficacy of STS in patients with major depressive disorder. METHOD: 365 outpatients 18 to 65 years old with a DSM-IV diagnosis of major depressive disorder were enrolled at 16 sites. A 17-item Hamilton Rating Scale for Depression (HAM-D-17) score of > or = 20 was required for entry. Patients were randomly assigned to receive either STS, 20 mg/20 cm(2), daily or placebo patch for up to 8 weeks. A tyramine-restricted diet was neither required nor advised. Efficacy, safety, and vital sign measures were obtained regularly. RESULTS: 289 patients were randomly assigned to treatment and received at least 1 on-therapy evaluation (STS, N = 145; placebo, N = 144). Although the effect size was modest, at endpoint, STS was statistically superior to placebo on the MADRS (p =.001) and HAM-D-28 (p =.039) ratings and showed a nonsignificant superiority on the HAM-D-17 (p =.069) and Clinical Global Impressions-Severity ratings (p <.055). Side effect profiles were similar for STS and placebo with the exception of application-site reaction, which was observed in 31.5% of STS patients and 15.1% of placebo-treated patients (p =.001). No significant differences were observed in blood pressure measures between treatment groups. CONCLUSION: Results from this double-blind, placebo-controlled clinical trial demonstrate that STS may have a modest, but statistically significant, antidepressant benefit compared with placebo and a similar safety profile compared with placebo in the absence of a tyramine-restricted diet.

Administration, Cutaneous↗
PubMed1976

[On the mode of action of heptaminol (author's transl)].

The effect of heptaminol, an aliphatic amine with an alcoholic group on carbon 2, on sympathetic nerves and on isolated chromaffine granules was infestigated. In cats, heptaminol caused long-lasting, dose-dependent pressor effects accompanied by tachycardia and contractions of the nictitating membrane. In comparison with tyramine, heptaminol was 100 times less potent in increasing blood pressure and 10 times less effective in inducing contractions of the nictitating membrane. The rise in blood pressure as well as tachycardia and contraction of the nictitating membrane were diminished by cocaine. After pretreatment with cocaine, heptaminol in high doses caused short-lasting depressor effects. Also in rats the pressor effect of heptaminol was weaker but of longer duration than that of tyramine. The dose-response curve was depressed by pretreatment with reserpine. The tachycardia induced by heptaminol was markedly diminished after pretreatment with reserpine. After repeated injections heptaminol reduced the norepinephrine content of the rat heart by 20-40%, Tyramine and hexylamine were more effective than heptaminol in depleting the norepinephrine stores of the heart (50-60%). In fluorescence microscopic investigations on sympathetic nerves (rat iris) depleted of norepinephrine by reserpine, the uptake of alpha-methylnorepinephrine could be inhibited or prevented by heptaminol. The spontaneous release of catecholamines from isolated bovine chromaffine granules was enhanced (+30%) by heptaminol or methamphetamine in high concentrations. In lower concentrations, however, both drugs reduced the uptake of 14C-epinephrine in isolated medullary granules by 20-40%. In addition a non-specific papaverine-like spasmolytic effect of heptaminol could be demonstrated. The results suggest that heptaminol exerts its pharmacological action by interfering with release and uptake of norepinephrine.

Adrenal Medulla↗
PubMed1976

Evidence for a physiological role of renal sympathetic nerves in adrenergic stimulation of renin release in the rat.

Previous studies on renin release by an in vitro system of rat kidney slices, which is devoid of hemodynamic influences, have provided evidence that renin release is stimulated by a beta-adrenergic mechanism. We used this system to study effects of tyramine (an indirectly acting amine capable of displacing endogenous catecholmines from sympathetic nerve endings) on renin release. Tyramine (10(-3)M) in the presence of a monoamine oxidase inhibitor (pheniprazine, 10(-5)M) and a phosphodiesterase inhibitor (theophylline, 10(-3)M) significantly (P less than 0.01) stimulated renin release when values were compared to control observations for media containing only the inhibitors. Tyramine-induced stimulation of renin release was blocked by the beta-blocking agent, propranolol (2 X 10(-4) M), and the neural uptake blocking agent, cocaine (10(-5) M), but not by the alpha-antagonist, phentolamine (9 X 10(-4) M). These observations demonstrate a potential role for the sympathetic innervation of the juxtaglomerular apparatus on renin release.

Animals↗
PubMed1975

Amine turnover in migraine.

Excretion of the vaso-active amines tyramine, serotonin, noradrenaline, adrenaline and histamine and blood levels of serotonin, noradrenaline, adrenaline and histamine, were estimated in 10 patients before, during and after an attack of migraine. During the headache process there was a statistically significant fall in the excretion of tyramine and a similarly significant rise in the excretion of serotonin. Excretion of the other 3 amines showed no significant fluctuation during the various phases of the migraine attack. Blood levels of serotonin were significantly lower during headache than during freedom from headach. whilst whole blood histamine was significantly higher only during the postheadach phase. The meaning of the latter observation is not obvious. The above results are discussed in the light of recent reports that tyramine is the substance responsible for headache attacks in patients who have a history of dietary migraine. Reasons are offered as to why this is unlikely to be the case.

Biogenic Amines↗
PubMedDate not supplied

Hemicrania continua and chronic paroxysmal hemicrania: a comparison of pupillometric findings.

Pupillometric studies were carried out in 9 patients with chronic paroxysmal hemicrania (CPH), in 10 patients with hemicrania continua (HC) and in age- and sex-matched controls (n = 12-17). Studies were carried out in the basal condition and after instillation of 2% tyramine, 1% OH-amphetamine, or 1% phenylephrine. The pupillary response to tyramine in HC was more marked than in controls on a percentage increase basis, but not so much when the increment is calculated in absolute values. In this series, there was no asymmetrical response (relative miosis on the symptomatic side) like in previous case reports. The pupil reaction was less in HC than in CPH after hydroxyamphetamine instillation and without any marked asymmetry. There was no definite evidence of supersensitivity to a directly acting sympathicomimetic agent, phenylephrine. No gross abnormalities as regard the sympathetic function in HC was thus observed. The asymmetry on tyramine testing differed in CPH and HC (most marked in HC). No major emphasis should probably be attached to this finding, since on testing with OH-amphetamine, a similar substance, this finding was not reproduced.

Adult↗
PubMed2005

The presence of trace amines in postmortem cerebrospinal fluid in humans.

The postmortem levels of biogenic amines in cerebrospinal fluid may represent a useful tool in defining some pathological conditions; no information is available concerning the occurrence of trace amines in postmortem cerebrospinal fluid. Thus, the occurrence of octopamine, synephrine and tyramine were evaluated by using a HPLC system in 20 postmortem samples of cerebrospinal fluid (obtained from 11 males and 9 females) and their levels were compared with those of 20 living subjects (obtained from 11 males and 9 females). The results show that trace amines dramatically increase in the postmortem cerebrospinal fluid (100, 20, and 4 fold increase for tyramine, octopamine, and synephrine respectively). To our knowledge, our data represent the first time trace amines have been identified in postmortem cerebrospinal fluid and the dramatic increase observed for tyramine has the potential of becoming a new tool in forensic science for better defining the time of death.

Amines↗
PubMed1991

Effect of subarachnoid hemorrhage on serotonin uptake and release in the rabbit basilar artery.

This study analyzes the changes induced by subarachnoid hemorrhage (SAH) on the serotonin (5-hydroxytryptamine, 5-HT) uptake and release evoked in rabbit basilar arteries by tyramine. Rabbits were injected with 5 ml of autologous arterial blood into the cisterna magna to produce SAH. Tritium accumulation in basilar arteries was measured after 30 minutes of incubation with 10(-7) M [3H]5-HT and a subsequent 120-minute superfusion (1 ml/min) period. The uptake of 5-HT by arteries 1, 2, 3, and 7 days after SAH was found to be 109%, 69%, 57% (P less than 0.05), and 67% (P less than 0.05) (n = 4, 4, 9, and 6; P less than 0.05) of control (n = 13; 16.8 +/- 1.2 X 10(2) dpm/mg tissue), respectively. The neuronal (cocaine-sensitive) uptake of 5-HT in the arteries 3 days after SAH decreased to approximately 38% of control, whereas the extraneuronal (cocaine-insensitive) uptake of both groups had almost the same absolute value (n = 6 and 6; 4.4 +/- 0.4 and 4.8 +/- 0.4 X 10(2) dpm/mg). Autoradiographic study disclosed that dense clusters of silver grains in the adventitia were not observed after treatment with cocaine (3 X 10(-5) M), although a diffuse distribution of grains was present throughout the vascular wall. The labeled arteries were stimulated by superfusion of tyramine, which is known to replace amines in the sympathetic nerve ending. Tyramine (10(-6) and 10(-4) M)-induced 3H efflux was significantly potentiated by SAH (n = 6) and was suppressed by treatment with cocaine.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Stereochemical trends in copper amine oxidase reactions.

Copper amine oxidases (EC 1.4.3.6) exhibit atypical stereochemical patterns in the reactions they catalyze. Dopamine and tyramine are oxidized with abstraction of the pro-R hydrogen by the porcine plasma amine oxidase, the pro-S hydrogen by pea seedling amine oxidase and a net nonstereospecific proton abstraction by the bovine plasma enzyme. This provides the first example in which a reaction catalyzed by enzymes in the same formal class occurs by all three possible stereochemical routes. To assess the underlying mechanistic significance of this heterogeneity, we have established the stereochemical course of the oxidation of tyramine by five additional copper amine oxidases using 1H NMR spectroscopy. Reactions catalyzed by rabbit and sheep serum amine oxidases are nonstereospecific. These enzymes exhibit rare mirror image binding with differential flux through two opposite and stereospecific reaction pathways. Differential primary kinetic isotope effects are observed for each mode, 8 and 4.6 for pro-S abstraction and 2.6 and 2.7 for pro-R abstraction by the sheep and rabbit amine oxidases, respectively. Tyramine oxidations catalyzed by the soybean and chick pea amine oxidases and porcine kidney diamine oxidase, however, are all stereospecific, occurring with loss of the pro-S hydrogen at C-1. Solvent exchange profiles are consistent within each stereochemical class of enzyme; the pro-R and nonstereospecific enzymes exchange solvent into C-2 of product aldehydes, the pro-S enzymes do not.

Amine Oxidase (Copper-Containing)↗
PubMed1991

Nuclear imaging analysis of human low-density lipoprotein biodistribution in rabbits and monkeys.

We have evaluated the biodistribution of human low-density lipoprotein (LDL) radiolabeled with 99mTc or with 123I-tyramine cellobiose in rabbits and in rhesus monkeys. Biodistribution was assessed after intravenous injection of radiolabeled LDL by quantitative analysis of scintigrams, counting of excreta, and counting of tissues at necropsy. Both rabbits and monkeys showed lower renal uptake (123I:99mTc approximately 1:3, as regional percent injected activity corrected for physical decay) and excretion (1:2 to 1:4), but higher hepatic (1.5:1 to 2:1) and cardiac (1.7:1 to 4:1) uptake of 123I than of 99mTc. Adrenals were visualized in normolipemic animals with 123I-tyramine cellobiose-LDL but not with 99mTc-LDL. Hyperlipemic animals showed increased cardiac (up to six-fold) and decreased hepatic activity (by 50%-60%) of both radionuclides. We conclude that 123I-tyramine cellobiose-LDL is better suited than 99mTc-LDL for dynamic studies of LDL metabolism in vivo.

Animals↗
PubMed1990

Role of alpha-1 and alpha-2 adrenoceptors in the sympathetic control of the proximal urethra.

In the pithed rat, postjunctional alpha-1 and alpha-2 adrenoceptors mediate increases in proximal urethral perfusion pressure (UPP). The present study examined the role of alpha-1 and alpha-2 adrenoceptors in sympathetic control of the isolated in situ proximal urethra of the rat. An endogenous alpha adrenergic constriction was demonstrated in the proximal urethra by eliciting dose-related and phentolamine-sensitive increases in UPP after the systemic administration of tyramine. Transient dose-related and hexamethonium-sensitive increases in UPP were also elicited by ganglionic stimulation with 1,1-dimethyl-4-phenylpiperazinium (DMPP). Based on the relative sensitivity of the DMPP response to standard autonomic blockers, it was determined that constriction is the predominant autonomic response in the proximal urethra and this response is mediated by alpha adrenoceptor mechanisms. Prazosin, a selective alpha-1 adrenoceptor antagonist, substantially reduced (72%) the steady-state increases in UPP elicited by discrete low frequency electrical stimulation of the spinal hypogastric outflow. In contrast, selective alpha-2 adrenoceptor blockade with rauwolscine significantly increased (28%) the UPP response to hypogastric stimulation. Prazosin also abolished the increase in urethral tone elicited by tyramine, whereas rauwolscine had no effect on the tyramine. A different response profile was observed for prazosin and rauwolscine when the steady-state increase in UPP was evoked by simultaneously stimulating the midthoracic and hypogastric spinal outflow. Under these conditions of sympathoadrenal activation, UPP was reduced by both prazosin and rauwolscine (63 and 50%, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Effects of sympathetic activation on plasma renin activity in the developing rat.

The present experiments studied the ontogeny of sympathetic control of the renin-angiotensin system by using pharmacological agents, which act at different levels of the sympathetic axis, to increase plasma renin activity (PRA) during the preweanling period in Sprague-Dawley rats. The selective beta-1 adrenoceptor agonist, prenalterol, produced age- and dose-dependent PRA increases. In 5- and 10-day-old animals, prenalterol treatment produced minimal stimulation of PRA and the dose-response curve was essentially flat. In contrast, greater PRA responses to increasing doses of prenalterol were found in 15- and 20-day-old animals. The PRA response to tyramine, which causes norepinephrine release from postganglionic sympathetic fibers, gradually increased between 5 and 20 postnatal days of age, first producing significant stimulation on day 15. Centrally mediated sympathetic activation with yohimbine also produced age-dependent stimulation of PRA that was comparable to the increases produced by tyramine between postnatal days 10 and 20. However, in contrast to tyramine, yohimbine produced a significant increase in PRA on postnatal day 5. The present results suggest that functional sympathetic control of the renin-angiotensin system matures during the second to third postnatal week in the Sprague-Dawley rat, and this may be related to the development of beta-1 adrenoceptors in the kidney that regulate renin release.

Age Factors↗
PubMed1989

Selective pressor enhancement by monoamine oxidase inhibitors in conscious rats.

To compare the cardiovascular effects of chronic monoamine oxidase (MAO) A and B inhibition, rats were given s.c. injections of saline clorgyline or l-deprenyl daily for 3 weeks. Indwelling vascular catheters and a Doppler flow probe were implanted chronically to allow subsequent recording of femoral pressure, heart rate and iliac blood flow before and during the treatment while the rats were awake. On days 7 and 21, average femoral pressure were significantly higher in rats treated with either saline or l-deprenyl than in those treated with clorgyline. Pressor responses elicited by injecting graded doses of phenylephrine, angiotensin or tyramine i.v. were always accompanied by bradycardia and reduced iliac flow. Magnitude of all responses was unaltered in control rats treated with the saline vehicle. In rats treated with l-deprenyl responses to tyramine were enhanced slightly, but in those treated with clorgyline enhancement was more pronounced and included not only responses to tyramine but also those to phenylephrine and angiotensin. Because clorgyline inhibits MAO A whereas l-deprenyl inhibits MAO B our findings imply that enhanced pressor responsiveness depends on inhibition of MAO A rather than MAO B.

Animals↗
PubMed1988

Radiotracers for low density lipoprotein biodistribution studies in vivo: technetium-99m low density lipoprotein versus radioiodinated low density lipoprotein preparations.

In an attempt to characterize the in vivo behavior of [99mTc] low density lipoprotein (LDL), biodistribution studies were performed in normal and hypercholesterolemic (HC) rabbits. In normal rabbits, 24 hr after the injection of [99mTc]LDL, 99mTc activity accumulated mainly in adrenal glands, spleen, liver, and kidney. In HC rabbits, however, there was a marked reduction of 99mTc activity in these organs. In both normal and HC rabbits, less than 17% of 99mTc activity appeared in the 24-hr urine following injection of [99mTc]LDL, suggesting that in vivo, [99mTc]LDL is trapped and accumulated within the tissues. Direct comparison of [99mTc]LDL, 125I-native-LDL and [131I]tyramine cellobiose-LDL (the previously validated trapped radioligand) in normal rabbits, demonstrated that the biodistribution of [99mTc]LDL was similar to that of [131I]tyramine cellobiose-LDL. The adrenal glands, liver, and spleen accumulated significantly greater quantities of 99mTc and 131I activity per gram of tissue than 125I (from native-LDL). In addition, imaging studies in monkeys, showed that the hepatic uptake and retention of [99mTc] LDL was similar to that of [131I]tyramine cellobiose LDL. In contrast, radioiodine from native-LDL was deiodinated in liver with subsequent excretion into the intestine. These results suggest that [99mTc]LDL acts as a trapped ligand in vivo and should therefore, be a good tracer for noninvasive quantitative biodistribution studies of LDL.

Animals↗
PubMed1987

Norepinephrine depletion and sensitivity changes in rat heart induced by pretreatment with reserpine.

Depletion of norepinephrine, sensitivity to isoproterenol and sensitivity to tyramine in rat atria were investigated after various doses and schedules of pretreatment of rats with reserpine. Virtually complete depletion of norepinephrine occurred in both right and left atria and ventricles after doses of 1.0 mg/kg/day of reserpine for one or more days of pretreatment. A smaller dose, 0.3 mg/kg/day, produced lesser depletion, and a larger dose, 2.5 mg/kg/day, caused severe central nervous system depression and high mortality. Chronic treatment (5 days or longer) with the 1.0-mg/kg/day dose produced supersensitivity of right atria to the chronotropic, but not inotropic, responses to isoproterenol. Chronic treatment with this dose for 7 days produced inotropic supersensitivity in left atria. Most of the schedules of pretreatment with reserpine depressed the maximum response to tyramine. However, the data indicate that the tyramine-releasable norepinephrine was not a consistent reflection of the total norepinephrine pool, even when depletion was very pronounced. The effects of depletion of cardiac stores of norepinephrine with reserpine in comparison with the effects of cardiac sympathectomy are discussed.

Animals↗
PubMed1987

Recently identified nitrite-reactive compounds in food: occurrence and biological properties of the nitrosated products.

Various Japanese foodstuffs are directly-acting mutagens in Salmonella typhimurium TA100 after nitrite treatment. Such mutagen precursors include tyramine and beta-carboline derivatives, isolated from soya sauce, and indole-3-acetonitrile, 4-methoxyindole-3-acetonitrile and 4-methoxyindole-3-aldehyde, isolated from fresh Chinese cabbage. A mutagen produced from tyramine with nitrite was found to be 4-(2-aminoethyl)-6-diazo-2,4-cyclohexadienone (3-diazotyramine), and one produced from indole-3-acetonitrile with nitrite to be 1-nitrosoindole-3-acetonitrile. These two mutagens were directly-acting mutagens not only in S. typhimurium TA100 and TA98 but also in Chinese hamster lung cells, using diphtheria toxin resistance as a selective marker. The carcinogenicity of 3-diazotyramine was demonstrated in male Fischer 344 rats. Tyramine, beta-carboline and indole compounds are present ubiquitously in our environment, especially in foods. Therefore, the role of these newly identified mutagen precursors in the development of human cancer should be taken into consideration.

Acetonitriles↗