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At least 1,711 records · Page 95Linked to original sources
PubMed1997

Developmental changes in serotonergic receptor-mediated modulation of embryonic chick motoneurons in vitro.

Intracellular recordings were obtained from antidromically identified motoneurons in an embryonic chick spinal cord slice preparation at two developmental stages (embryonic days 12 and 18, E12 and E18) which bracket a critical period in spinal cord growth. The resting membrane potential of chick motoneurons did not change significantly between E12 and E18, but there was a significant decrease in neuronal input resistance. A small inward rectification was present in cells of both ages, although a lower proportion of E12 motoneurons exhibited inward rectification compared to E18 motoneurons. Injection of depolarizing current pulses revealed that most E12 motoneurons exhibited spike adaptation, while the majority of E18 motoneurons showed high frequency tonic firing. Bath application of serotonin (5-HT) and its agonists 5-carboxamido-tryptamine (5-CT, a 5-HT1 agonist) and alpha-methyl 5-HT (a 5-HT2 agonist) produced hyperpolarizing responses accompanied by decreased input resistance in all E12 motoneurons studied. The same three agonists produced depolarizing responses and increased input resistance in all E18 motoneurons studied. The effects of serotonergic agonists on motoneuronal excitability were tested using depolarizing current pulses. In most cases, serotonergic agonists caused a decrease in firing frequency during the hyperpolarizing response in E12 neurons. At E18, bath application of 5-HT, 5-CT or alpha-methyl 5-HT produced an increase in firing frequency in all motoneurons during the depolarizing response. Our results indicate that both 5-HT1 and 5-HT2 receptor subtypes contribute to modulation of chick motoneuron excitability and appear to reverse the polarity of their effects on membrane potential after a critical period in development of the spinal cord.

Analysis of Variance↗
PubMed1995

Melatonin receptors: are there multiple subtypes?

There is now evidence for more than one site of action for the hormone melatonin (N-acetyl-5-methoxy-tryptamine). Recent pharmacological and molecular advances are providing the tools to address the characterization of melatonin receptor subtypes. The development of novel melatonin receptor agonists and antagonists, high-affinity radioligands, quantitative bioassays, and the recent cloning of melatonin receptors are furthering our understanding of native and recombinant melatonin receptors. In this article, Margarita Dubocovich discusses the properties of melatonin receptors, and the basis for their classification into at least two subtypes, the ML1 and ML2.

Amino Acid Sequence↗
PubMed2002

Behavioral responses to ingestion of different sources of fat. Involvement of serotonin?

In previous experiments, we described a decrease in extracellular hypothalamic serotonin, 5-hydroxy-tryptamine (5-HT), in response to ingestion of a lard meal. This effect was related to the low satiating potency of lard as compared with other nutrients. Since the composition in fatty acids might be important for these effects, the purpose of this study was to analyze the neurochemical and behavioral responses to ingestion of different sources of fat. Unique meals of three margarines used in human feeding were compared with a meal of lard with regard to their effects on hypothalamic 5-HT, satiety, anxiety-like behavior and sucrose consumption. A vegetable margarine with a high content in saturated fatty acids also decreased hypothalamic 5-HT while ingestion of a sunflower oil and an olive oil enriched margarines, both high in polyunsaturated fatty acids, did not affect significantly 5-HT levels. However, these two last ones were not the most satiating. The olive oil margarine induced a tendency to an anxiety-like behavior while lard increased sucrose consumption. Thus, ingestion of fats may alter specifically behavioral responses. The involvement of 5-HT is likely in the case of lard ingestion but probably not for the other sources of fat.

Animals↗
PubMed2000

Effects of serotoninergic drugs on tremor induced by physostigmine in rats.

We investigated the effects of various serotoninergic drugs and serotonin (5-HT) depletion on physostigmine-induced visible tremor in rats. Physostigmine (0.25-1.5 mg/kg) caused dose-dependent tremor, initiated at 3-5 min (latency decreases as dose increases) and lasted for 30-35 min. Serotonin agonists, 8-hydroxy-2-(di-n-propylamino) tetralin (2.5 mg/kg) and buspirone (5 mg/kg) augmented the tremor response caused by physostigmine. The 5-HT(1)/5-HT(2) receptor antagonist, metergoline (1 mg/kg), and 5-HT(2) blocker, cyproheptadine (10 mg/kg) significantly decreased the duration (40%) as well as intensity (45-50%) of physostigmine-tremor. The 5-HT(2a)/5-HT(2c) antagonist ritanserin (5 mg/kg) significantly reduced the duration (60%) without affecting the intensity of the tremor. In 5-HT depleted rats (p-chlorophenylalanine; 300 mg/kg, for 3 days), physostigmine failed to produce tremor. Interestingly, in these animals, administration of a non-specific 5-HT agonist, 5-methoxy-N,N-dimethyl tryptamine, caused high intensity tremor. These results suggest that presence of 5-HT at the pre-synaptic terminals is needed for the tremor response by physostigmine and the response is greatly mediated via post-synaptic 5-HT receptors. The overall data indicated a direct involvement of central 5-HT system in the cholinergic tremor induced by physostigmine.

Animals↗
PubMed2001

Effect of the interaction between a low tyramine-producing Lactobacillus and proteolytic staphylococci on biogenic amine production during ripening and storage of dry sausages.

The interaction between tyrosine-decarboxylase and proteolytic activities of a Lactobacillus curvatus and Staphylococcus xylosus, respectively, on biogenic amine production during the ripening and the storage of dry fermented sausages was investigated. Water content, pH, proteolysis parameters, microbial counts, and biogenic amine contents were monitored in spontaneously and starter fermented sausages. The use of proteolytic staphylococci as starter resulted in a higher content of non-protein nitrogen and total free amino acids. Tyramine was the main amine produced in all batches. However, tyrosine-decarboxylase activity of the L. curvatus starter strain was weak and yielded lower amounts of tyramine than those produced by the wild mioroflora in the control batch. Association between tyramine production and proteolysis could only be established in a defectively dried batch. Putrescine and cadaverine accumulation was efficiently reduced in the starter-mediated fermentation, in agreement with the lower development of enterobacteria. Phenylethylamine and tryptamine were only detected in the spontaneously fermented sausages, while histamine, spermine and spermidine did not vary during the ripening. Biogenic amine levels and related parameters showed significant changes during the storage of dry sausages depending on the temperature and the batch. As a general rule, changes in the pH, proteolysis, microbial counts, and biogenic amine contents were stronger at 19 degrees C than at 4 degrees C. The results suggest that refrigeration would be advisable for preventing further accumulation of biogenic amines during the storage of dry fermented sausages.

Biogenic Amines↗
PubMed2001

Amino acid-decarboxylase activity of bacteria isolated from fermented pork sausages.

The occurrence of amino acid-decarboxylase activity in 92 strains of lactic acid bacteria, coagulase-negative staphylococci, and Enterobacteriaceae isolated from Spanish fermented pork sausages was investigated. The presence of biogenic amines in a decarboxylase synthetic broth was determined by ion-pair high performance liquid chromatography with o-phtalaldehyde post-column derivatization. Among the 66 lactic acid bacteria strains tested, 21 lactobacilli (in particular, Lactobacillus curvatus) and all 16 enterococci were amine producers. Tyramine was the main amine produced by these bacteria, although they also produced phenylethylamine, tryptamine, and/or the diamines putrescine and cadaverine. None of the lactic acid bacteria produced histamine. Coagulase-negative staphylococci were found to be negative amine-producers. Aromatic monoamines, apart from histamine, were not formed by Enterobacteriaceae. This family was responsible for cadaverine and putrescine production. The results obtained for biogenic amine production by bacteria in a synthetic medium suggest that amino acid-decarboxylase activity is strain dependent rather than being related to specific species.

Animals↗
PubMed2003

Biogenic amines in dry fermented sausages: a review.

Biogenic amines are compounds commonly present in living organisms in which they are responsible for many essential functions. They can be naturally present in many foods such as fruits and vegetables, meat, fish, chocolate and milk, but they can also be produced in high amounts by microorganisms through the activity of amino acid decarboxylases. Excessive consumption of these amines can be of health concern because their not equilibrate assumption in human organism can generate different degrees of diseases determined by their action on nervous, gastric and intestinal systems and blood pressure. High microbial counts, which characterise fermented foods, often unavoidably lead to considerable accumulation of biogenic amines, especially tyramine, 2-phenylethylamine, tryptamine, cadaverine, putrescine and histamine. However, great fluctuations of amine content are reported in the same type of product. These differences depend on many variables: the quali-quantitative composition of microbial microflora, the chemico-physical variables, the hygienic procedure adopted during production, and the availability of precursors. Dry fermented sausages are worldwide diffused fermented meat products that can be a source of biogenic amines. Even in the absence of specific rules and regulations regarding the presence of these compounds in sausages and other fermented products, an increasing attention is given to biogenic amines, especially in relation to the higher number of consumers with enhanced sensitivity to biogenic amines determined by the inhibition of the action of amino oxidases, the enzymes involved in the detoxification of these substances. The aim of this paper is to give an overview on the presence of these compounds in dry fermented sausages and to discuss the most important factors influencing their accumulation. These include process and implicit factors as well as the role of starter and nonstarter microflora growing in the different steps of sausage production. Moreover, the role of microorganisms with amino oxidase activity as starter cultures to control or reduce the accumulation of biogenic amines during ripening and storage of sausages is discussed.

Amine Oxidase (Copper-Containing)↗
PubMed1998

Histamine and tyramine degradation by food fermenting microorganisms.

Microorganisms suitable for food fermentation were examined with regard to their potential to degrade histamine and tyramine. Out of 64 lactic acid bacteria evaluated in this study, 27 degraded histamine and one tyramine, respectively, with low activity. Among 32 strains of Brevibacterium linens and coryneform bacteria, 21 exhibited histamine and tyramine oxidase activity. None of 20 strains of Staphylococcus carnosus tested degraded histamine or tyramine. One strain out of nine strains of Geotrichum candidum degraded tyramine slightly. Among 44 strains of Micrococcus sp. examined, 17 degraded either one or two biogenic amines. In this study Micrococcus varians (M. varians) LTH 1540 exhibited the highest tyramine oxidase activity of all strains tested and was therefore investigated in detail. The enzyme was found to be located in the cytoplasm and was not membrane bound. The reaction end product p-hydroxyphenyl acetic acid was detected by HPLC analysis. An activity staining for the amine oxidase in a native polyacrylamide gel based on the formation of H2O2 during amine oxidation was developed. Resting cells of the strain exhibited optimal tyramine oxidase activity at a pH of 7 at 37-40 degrees C. The enzyme in the cell free extract had a pH optimum between 7-8. The enzyme activity was decreased by NaCl, glucose and hydralazine. Phenylethylamine and tryptamine were oxidized at lower concentrations than tyramine. The potential for amine degradation was not found to be associated with that of formation of biogenic amines, as 23 microorganisms with the ability to metabolise biogenic amines exhibited no decarboxylase activity toward histidine, tyrosine, phenylalanine, lysine or ornithine.

Fermentation↗
PubMed1999

Effect of proteolytic starter cultures of Staphylococcus spp. on biogenic amine formation during the ripening of dry fermented sausages.

The effect of proteolytic starter cultures of Staphylococcus carnosus and Staphylococcus xylosus on biogenic amine production was examined during the fermentation process of dry sausages. Microbial counts (lactic acid bacteria, Micrococcaceae and Enterobactenaceae), pH, moisture and proteolysis-related parameters were also studied. The polyamines spermine and spermidine were the main amines found in the raw material and they only showed slight fluctuations during the fermentation. The four elaborated batches presented a significant (P < 0.001) formation of tyramine and putrescine. The main rate of amine production was during the first three days, when a sharp pH decrease and the development of lactic acid bacteria occurred. Sausages fermented with starters had lower amounts of tyramine than naturally fermented sausages (control), but differences in the Micrococcaceae counts were only significant during the first week of the ripening process. A slight formation of diaminopropane, cadaverine, agmatine, tryptamine and phenylethylamine was observed. The amounts of histamine were constant and remained below 0.5 mg/kg of dry matter, while serotonin, octopamine and dopamine were not detected. The sausages with Staphylococcus as starter culture showed strong proteolysis that was correlated with higher pH values than those of the control sausages. However, no positive correlation was found between the proteolysis index and biogenic amine production. Since proteolysis was stronger during the second half of the ripening process, the release of free amino acids as amine precursors occurred later than the early amine production.

Animals↗
PubMed1999

Neuropeptide Y release by pumiliotoxin-B in the electrically-stimulated mouse vas deferens: an immunohistochemical study.

Morphologic and immunohistochemical studies were conducted to ascertain whether pumiliotoxin-B (PTX-B), an indolizine alkaloid from the skin of the Neotropical dendrobatid frog, Dendrobates pumilio, affects the anatomic and immunohistochemical features of the electrically stimulated mouse vas deferens preparations. PTX-B, at a concentration of 1 microM, consistently decreased the density pattern of neuropeptide Y (NPY)-immunoreactive nerve fibers contained within the circular muscular layer. The alkaloid also induced striking morphologic changes. It enlarged the lumen of the vasa and relaxed the muscular wall. Pretreatment with prazosin or haloperidol affected neither the release of NPY nor the morphologic changes; pretreatment with tetrodotoxin and guanethidine abolished NPY release and prevented the PTX-B-induced morphologic changes. PTX-B had no appreciable effect on the density and distribution pattern of nerve fibers immunostained for vasoactive intestinal polypeptide, substance P, calcitonin gene-related peptide, enkephalin, pancreatic polypeptide, 5-hydroxy-tryptamine and tyrosine hydroxylase.

Alkaloids↗
PubMed1982

Some aspects of basic psychopharmacology: the trace amines.

1. Some recent research on the behavioural effects of phenylethylamine and some recent data implicating the trace amines in schizophrenia, agoraphobia and aggression are briefly outlined. 2. Phenylethylamine produces in mice a distinctive hyperactivity syndrome consisting of two phases; it appears to act via dopamine and 5-hydroxytryptamine on different components of these stereotypies. 3. Urinary unconjugated tryptamine, and meta- and para-tyramine appear to be excreted in reduced amounts in schizophrenia and bipolar depression. 4. The blood levels of the trace acids phenylacetic and meta- and para-hydroxyphenylacetic are reduced in schizophrenia. 5. Blood levels of conjugated phenylacetic and unconjugated para-hydroxyphenylacetic acid are reduced in violent as opposed to non-violent offenders. 6. The neuromodulatory role of the trace amines and their possible involvement in components of behaviour and certain mental disorders are discussed.

Aggression↗
PubMed1985

[Simple compounds with high pharmacologic potential: beta-carbolines. Origins, syntheses, biological properties].

We reviewed the origins, the synthetic pathways and the biological properties of beta-carbolines, the condensation products of tryptophan and indole alkylamines with aldehydes. They were found in many plants, some of which have been used as hallucinogens. They also occur as minor constituents in tobacco smoke. In mammalian body, beta-carboline derivatives occur normally in plasma, platelets and urine, moreover it seems that some are formed in human body after alcohol intake. Due to interesting biological effects described in recent years (inhibition of monoamine oxidase, binding to benzodiazepine receptors, comutagenic and carcinogenic properties, 5-hydroxy tryptamine uptake inhibition), many attempts were made to prepare beta-carbolines starting from various indole derivatives. We reviewed the published methods up to 1975 and summarized the main patents related with pharmacological properties of synthetic beta-carbolines.

Alcohol Drinking↗
PubMed1997

5-HT 1B/D receptor antagonists.

1. 5-Hydroxytryptamine-1B (5-HT 1B, formerly designated 5-HT 1D beta) and 5-hydroxy-tryptamine-1D (5-HT 1D, formerly designated 5-HT 1D alpha) receptors are distinct molecular entities that mediate serotonergic neurotransmission. Both are G-protein-coupled receptors without introns in their coding region, negatively coupled to adenylate cyclase; their precise function in human beings remains to be defined. In brain, they are highly enriched in the globus pallidus and the substantia nigra. 2. Presynaptic 5-HT 1B/D receptors take part in the control of the release not only of 5-HT itself, but also of other neurotransmitters-for example, acetylcholine, glutamate, dopamine, noradrenaline and gamma-aminobutyric acid. Selective blockade of central 5-HT 1B/D autoreceptors should facilitate 5-HT neurotransmission and may offer a novel approach to antidepressant therapy. Other 5-HT 1B/D receptors are located postsynaptically; those receptors may be supersensitive in the pathophysiology of obsessive-compulsive disorder and may be a potential target for its treatment. 3. Few if any ligands show selectivity for 5-HT 1B or 5-HT 1D receptors or both. Most pharmacological studies have been performed with nonselective antagonists-for example, metergoline, I-naphthylpiperazine, methiothepin, ketanserin and ritanserin. Recently, a novel series of benzanilides have been reported as the first examples of selective 5-HT 1B/D receptor antagonists. GR 127935, a representative compound of this series, displays mixed agonist-antagonist properties both in vitro and in vivo. It induces upon systemic administration in the guinea pig either an opposite (decrease) effect or a small increase (65%, 5 mg/kg) in the concentration of cortical extracellular 5-HT compared with fluoxetine (218%, 10 mg/kg). The importance of blockade of 5-HT 1B/D receptors in the raphé region, their possible interaction with 5-HT 1A receptors, and consequent inhibition of 5-HT release in terminal 5-HT 1B/D receptor-containing regions are discussed. 4. To find out whether the available so-called 5-HT 1B/D receptor antagonists are indeed antagonists and not partial agonists, efficacy was measured at recombinant human 5-HT 1B and 5-HT 1D receptor sites by using a [35S]-GTP gamma S binding assay to membrane preparations of stably transfected rat C6-glial cell lines. Metergoline and the selective 5-HT 1B/D receptor ligands GR 127935 as well as GR 125743 showed significant intrinsic activity (43% to 69%) at the 5-HT 1D receptor subtype, whereas the nonselective ligand 1-naphthylpiperazine yielded less (15% to 19%) intrinsic activity at both receptor subtypes. In contrast, the nonselective ligands methiothepin, ketanserin and ritanserin are inverse agonists because they displayed negative efficacy (-14% to -28%). Differential blockade of 5-HT 1B/D receptors by neutral antagonists and inverse agonists is discussed in relation to the 5-HT tone on 5-HT 1B/D receptors. 5. It can concluded that 5-HT 1B/D receptor ligands modulate 5-HT neurotransmission through a terminal 5-HT 1B/D receptor. Future work should be directed toward the identification of selective 5-HT 1B and 5-HT 1D receptor ligands that display either neutral antagonist or inverse agonist properties to evaluate the therapeutic potential of 5-HT 1B/D receptor blockade.

Animals↗
PubMed2000

Development of a method for sample preparation for subsequent identification and measurement of 1,2,3,4-tetrahydroisoquinolines and other potentially neurotoxic compounds by high-performance liquid chromatography with ultraviolet and fluorescence detection in blood plasma of Parkinson's disease patients.

We developed sample preparation methods for the detection of various biogenic phenylethylamine derivatives such as 3,4-dihydroxyphenylalanine, and their cyclisation products with aldehydes, i.e., 1,2,3,4-tetrahydroisoquinoline derivatives in blood samples. 1,2,3,4-Tetrahydroisoquinolines are considered to play an essential role as neurotoxic compounds in the pathomechanism of Parkinson's disease. We used reversed-phase high-performance liquid chromatography with ultraviolet and fluorescence detection for separation and identification. Ultrafiltration, protein precipitation and solid-phase extraction were investigated for purification of blood samples and enrichment of various compounds with a wide range of hydrophilicity and hydrophobicity. Protein precipitation by methanol and perchloric acid is a fast method to separate the analytes from the plasma matrix. A higher yield of the analytes is attained with prior addition of an alkylsulfonic acid giving a fine-grained precipitate. With the addition of ion pairing compounds into the sample it is possible to enrich not only lipophilic compounds such as norharman, tryptamine and melatonin, but also hydrophilic ones such as 3,4-dihydroxyphenylalanine by reversed-phase solid-phase extraction. Ultrafiltration is not useful as a screening method.

Blood Proteins↗
PubMed1982

Thin-layer chromatographic determination of indolic tryptophan metabolites in human urine using Sep-Pak C18 extraction.

Tryptophan and some of its indole metabolites were separated by thin-layer chromatography, stained with the Van Urk--Salkowski reagent, and quantitated by scanning densitometry. The application of this technique for the detection of the indoles in urine samples, employing Sep-Pak C18 cartridges for extraction, was demonstrated. The proposed method is simple and accurate. The detection limits were 2 micrograms/ml 5-hydroxytryptophan, 1.75 micrograms/ml 5-hydroxyindolyl-3-acetic acid, 1.5 micrograms/ml tryptophan, 0.8 micrograms/ml indolyl-3-acetic acid, 0.9 micrograms/ml indolyl-3-butyric acid, 1.75 micrograms/ml serotonin, and 1.25 micrograms/ml tryptamine.

Chromatography, Thin Layer↗
PubMed1989

Isolation, separation and analysis in neurochemistry: trace amines and acids as an illustrative example.

In this brief overview various neurochemical isolation procedures that can be adopted for the analysis of several monoamine neurotransmitters/neuromodulators and their principal oxidatively deaminated metabolites are outlined. With respect to the trace amines, they can be identified and quantitated as their so-called dansyl derivatives after thin-layer chromatographic separation by mass spectrometric (MS) electron-impact (EI) ionisation followed by selected-ion monitoring (SIM) of their molecular ions. Deuterated homologues are added as internal standards at the start of the analytical procedure. The MS-EI-SIM procedure offers a tissue extract or releasate sensitivity of about 100 pg/g of tissue or fluid. In the case of tryptamine or phenylethylamine, by utilising different derivatives (N-acetylpentafluoropropionyl or N-acetylpentafluorobenzoyl), which cyclise to form perfluorinated spirocyclic compounds, it is possible using MS negative chemical ionisation techniques coupled with monitoring of the (M-HF) ions to achieve sensitivities for tissue extracts of 1 pg/g or less. Acidic and neutral metabolites (up to twelve of them can be assayed simultaneously) can be detected and quantitated in tissue extracts, releasates or biological fluids as their methylpentafluoropropionyl or trifluoroethyl-pentafluoropropionyl derivatives in the 100-1000 pg range using gas chromatographic-MS-SIM procedures.

Amines↗
PubMed1996

Endogenous alkaloids in man. XXVI. Determination of the dopaminergic neurotoxin 1-trichloromethyl-1,2,3,4-tetrahydro-beta-carboline (TaClo) in biological samples using gas chromatography with selected ion monitoring.

Highly chlorinated beta-carbolines have a potential in vivo relevance to Parkinson's disease. In this paper, a gas chromatographic method for the determination of the neurotoxic 1-trichloromethyl-1,2,3,4-tetrahydro-beta-carboline (TaClo), the condensation product of tryptamine and chloral hydrate, is described. The specific and sensitive assay involves purification of the biological samples by solid-phase extraction with C18 cartridges, derivatization with heptafluorobutyric anhydride, and chromatography on a non-polar fused-silica capillary column. Detection of TaClo was achieved by the registration of characteristic mass fragments of the TaClo heptafluorobutyric amide derivative using selected ion monitoring. The method was utilized to detect and quantify TaClo in blood, urine, bile, faeces, and brain tissue of rats treated with this alkaloid-type heterocycle. Four-fold deuterium-labelled TaClo was used as an internal standard.

Animals↗
PubMed1979

Chemical studies on medicinal Myristicaceae from Amazonia.

Drugs from Myristicaceae species are used in the Amazon region as hallucinogens and arrow poisons, as well as for the healing of infected wounds. The former effects were attributed by Schultes and Holmstedt to tryptamines and carbolines. The latter activity is now tentatively ascribed to pterocarpans and neolignans. This, and a proposal that the red colour of the bark resins may be due to oxidative dimers of flavans, are based on a review of the chemistry of Amazonian Myristicaceae.

Alkalies↗