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PubMed2000

Total syntheses of (+/-)-anchinopeptolide D and (+/-)-cycloanchinopeptolide D.

The first synthesis of (+/-)-anchinopeptolide D (4) has been accomplished in seven steps in 10% overall yield from octopamine hydrochloride (17), N-(Boc)glycine (16), and 5-amino-2-hydroxypentanoic acid (22). The key step is the aldol dimerization and hemiaminal formation of alpha-keto amide 26, which gives primarily protected anchinopeptolide D 27 under kinetically controlled conditions. Cycloanchinopeptolide D (31) has been prepared by the unprecedented head-to-head photodimerization of the two hydroxystyrylamides of 4 using the hydrophobic effect in water to force the two side chains into close proximity so that [2 + 2] cycloaddition is faster than trans to cis double bond isomerization. Coupling of amine 21 with pyroglutamic acid affords the naturally occurring tripeptide 35, which had been assigned glutamic acid structure 34.

Alkaloids↗
PubMed2004

Rapid quantitative assay for acaricidal effects on Sarcoptes scabiei var. suis and Otodectes cynotis.

Brimer et al. (Vet. Parasitol. 51: 123-135, 1993 and 59: 249-255, 1995) developed a migration assay for acaricidal effect of acetylcholinesterase inhibitors and macrocyclic lactones utilising Sarcoptes scabiei var. suis mites. In contrast to many others, this assay is fully quantitative but quite time-consuming. The aim of the present investigation was to modify this assay to become faster and simpler. As a result accurate determinations can now be obtained within 6h, as opposed to 24h. Furthermore it was demonstrated that also Otodectes cynotis mites can be used with only minor modifications of the procedures. The cholinesterase inhibitor diazinon and the formamide amitraz were used as acaricides. Thus, the mite migration assay now has been proven useful for acaricidal compounds belonging to three chemical groups with different modes of action, namely organophosphorous cholinesterase inhibitors, macrocyclic lactones acting on the glutamanergic/GABAegic motoneurons, and formamide inhibitors of the octopamine systems of arthropods.

Animals↗
PubMedDate not supplied

Peripheral modulation of mechano-sensitivity in primary afferent neurons.

Considerable attention has centered recently on the changes in neuron excitability and synaptic efficacy caused by certain biogenic amines and neuropeptides. These neuromodulators act at a wide variety of both central and peripheral targets, and bring about diverse biological results. In sensory pathways, modulation occurs at central input synapses of the primary afferents and at peripheral terminals of efferents. This study was undertaken to look at non-synaptic modulation of membrane potentials in peripheral sensory endings of identifiable receptors. Using intracellular recording from the three primary afferent fibres of a recently described simple crustacean stretch receptor, which lacks centrifugal control, we observed in vitro modulation of the sensory response by three neuroactive substances known to be present in vivo. Two neuroamines, serotonin and octopamine, depressed receptor potentials and impulse discharge whereas the pentapeptide proctolin enhanced both these components of the sensory response. The peripheral sensory modulation reported here for a lobster mechano-receptor may occur in many animal groups and sensory systems.

Animals↗
PubMed1996

Spatio-temporal dynamics of cyclic AMP signals in an intact neural circuitm.

The functional properties of neuronal networks can be reconfigured by a variety of modulatory neurotransmitters, which may alter the excitable properties of neurons or the strengths of synaptic connections. Many of these neuromodulators act via the intracellular second messenger cyclic AMP, but their effects on the spatial distribution of cAMP concentration have never been examined in an intact neural circuit. We therefore used the cAMP-indicator dye FICRhR (refs 1, 2) to investigate the effect of several neuromodulators (octopamine, dopamine, acetylcholine, serotonin and proctolin) on cAMP distribution in identified neurons of the lobster stomatogastric ganglion (STG). When added to the bath solution, each of these neuromodulators produced a unique pattern of cAMP transients among the different neurons of the STG. Electrical stimulation of neurons innervating the STG causes synaptic release of endogenous modulators, leading within a few seconds to local increases of cAMP in fine neurite branches, the site where many modulators are thought to act. After prolonged stimulation, cAMP diffuses from the site of production to throughout the neuritic tree and eventually to the cell body. Diffusion of cAMP may explain how transient localized inputs to a neuron can produce long-range effects such as long-term changes in gene expression.

Animals↗
PubMed1984

Acute effect of labetalol on blood pressure in relation to the sympathetic nervous system and plasma renin activity.

A single oral dose of 300 mg labetalol was given to 10 subjects with uncomplicated primary hypertension; its effects on blood pressure, heart rate (HR), plasma renin activity (PRA), and plasma concentration of catecholamines and of their major metabolites, octopamine ( OTP ), and dopamine-beta hydroxylase (DbH) were investigated. Although HR did not change after dosing, both systolic and diastolic blood pressure decreased in 2 hr and remained below control up to 12 hr. There was symptomatic orthostatic hypotension in two subjects in the first 2 hr after dosing. PRA decreased in the first 2 hr and followed a gradual rise that became significant at 24 hr. Although DbH did not change, plasma concentrations of norepinephrine (NE) and its major metabolites and of OTP increased between 2 and 4 hr after dosing and remained elevated up to 12 hr. There was no correlation between change in blood pressure and control levels or changes of PRA or NE concentrations.

Blood Pressure↗
PubMed1973

Phenethylamines in brain and liver of rats with experimentally induced phenylketonuria-like characteristics.

1. Phenethylamines were extracted from brain and liver of rats with phenylketonuria-like characteristics produced in vivo by inhibition of phenylalanine hydroxylase (EC 1.14.3.1) with p-chlorophenylalanine, with or without phenylalanine administration. To protect amines against oxidation by monoamine oxidase, pargyline was also administered. 2. beta-Phenethylamine was the major compound found in brain and liver. beta-Phenethanolamine and octopamine were also present, in lesser amounts, and the concentrations of these three amines paralleled blood phenylalanine concentrations. By comparison, tissues from control animals had only very low concentrations of these amines. 3. Small amounts of normetadrenaline, m-tyramine and 3-methoxytyramine were also found. 4. The inhibitors used, p-chlorophenylalanine and pargyline, gave rise to p-chlorophenethylamine and benzylamine respectively, the first via decarboxylation, the second probably by breakdown during extraction. 5. Distribution of phenethylamines in different brain regions and in subcellular fractions of rat brain cells was also investigated. The content of phenethylamine was highest in the striatum. 6. These findings are discussed in the light of changes occurring in human patients with uncontrolled phenylketonuria.

Animals↗
PubMed1988

Activation of insect cell adenylate cyclase by Bacillus thuringiensis delta-endotoxins and melittin. Toxicity is independent of cyclic AMP.

Insecticidal Bacillus thuringiensis (Bt) delta-endotoxins are cytolytic to a range of insect cell lines in vitro. Addition of Bt var. aizawai or var. israelensis toxins to Mamestra brassicae (cabbage moth) cells in vitro increased intracellular cyclic AMP, which was paralleled by activation of adenylate cyclase in isolated membranes. Var. kurstaki toxin, which does not lyse M. brassicae cells, had no effect on cyclic AMP concentrations in intact cells, but was able to stimulate adenylate cyclase in membrane preparations. In contrast, the bee-venom toxin melittin, which is also cytolytic, increased intracellular cyclic AMP in whole cells, but inhibited adenylate cyclase in isolated membranes. Octopamine and forskolin also increased cyclic AMP in cells, but were not cytolytic. When added to cells at concentrations exceeding their LC90 (concentration causing 90% cell death), melittin and var. israelensis toxins caused cell lysis without a concomitant increase in intracellular cyclic AMP. Taken together, these results suggest that activation of adenylate cyclase by cytolytic toxins is a secondary effect (related perhaps to interactions of these toxins with membrane lipids) and is neither necessary nor sufficient for cytolysis.

Adenylyl Cyclases↗
PubMed1993

Biogenic-amine acetylation: an additional function of the N-acetyltransferase from Fasciola hepatica.

The previously described polyamine N-acetyltransferase from Fasciola hepatica has been observed to have an additional function, the acetylation of biogenic amines. The activities for biogenic amines, diamines and polyamines were in a constant ratio throughout the purification process. Biogenic amines found to be substrates for the enzyme included tyramine, tryptamine, beta-phenylethylamine and histamine, with Km values of 0.12 mM, 0.26 mM, 0.30 mM and 0.76 mM respectively. Octopamine, 5-hydroxytryptamine and alpha-phenylethylamine were also acceptable as substrates, though to a lesser degree. The optimum pH for biogenic-amine acetylation was 7.5, and CoA was inhibitory to the process, with a Ki of 5.5 microM. N-Acetylation appears to play a major role in the amine metabolism of this trematode. We presume that acetylation represents the process by which the parasite inactivates excess amines.

Acetylation↗
PubMed2001

Functional expression of a locust tyramine receptor in murine erythroleukaemia cells.

The LCR/MEL system (Locus Control Region/Murine Erythroleukaemia cells) was employed to express and characterize the Locusta migratoria tyramine receptor (TyrLoc), an insect G protein-coupled receptor. Functional agonist-dependent responses were recorded in stable, tyramine receptor expressing cell clones (MEL-TyrLoc). Tyramine elicited a dose-dependent increase of cytosolic Ca2+-ions and an attenuation of forskolin-induced cyclic adenosine monophosphate (AMP) production. Octopamine was shown to be a weak agonist for both responses. In addition, yohimbine proved to be a potent tyramine receptor antagonist. This study reports the first application of the LCR/MEL expression system in functional assays for G protein-coupled receptors and therefore expands the capabilities of this system by exploiting the functionality of the signal transduction pathways.

Animals↗
PubMed1998

The altered plasma amino acid pattern is responsible for the paradoxical growth hormone response to the oral glucose tolerance test in liver cirrhosis.

OBJECTIVE: An increased basal growth hormone (GH) secretion and a parodoxical GH response to the oral glucose tolerance test (OGTT) have been reported in patients with liver cirrhosis. It has been suggested that the ratio between branched-chain amino acids (BCAAs) and aromatic amino acids (AAAs) (BCAA/ AAA ratio) may determine in part the brain concentration of the AAAs, since the BCAAs compete with the AAAs for entry across the blood-brain barrier, leading to the accumulation of false neurotransmitters such as octopamine and phenylethanolamine, which are able to stimulate GH secretion (via alpha 2-adrenergic stimulation). In this study we investigated the role of amino acids, particularly the BCAA/AAA ratio, in the paradoxical response of GH to the OGTT in patients with liver cirrhosis. PATIENTS AND DESIGN: Twelve non-diabetic patients with biopsy-proven cirrhosis of the liver underwent an OGTT. Three of the five patients with a paradoxical response of GH to the OGTT underwent a second oral glucose administration associated with an infusion of BCAA solution from -30 min until 180 min. RESULTS: During the OGTT, glucose and insulin levels increased from 4.8 +/- 0.2 to 9.6 +/- 0.7 mmol/l (P < 0.001) and from 18.8 +/- 2.6 to 104.4 +/- 13.8 mU/l (P < 0.005), respectively. GH levels increased from 8.6 +/- 2.6 to 22.4 +/- 10.8 mU/l although not significantly. Five patients had a paradoxical GH response to the OGTT. A negative correlation between serum GH values and BCAA/AAA ratio in the plasma at every time point of the OGTT was found. After co-administration of glucose and BCAA in three patients the BCAA/AAAs ratio increased, abolishing the paradoxical GH secretion. CONCLUSIONS: Our data suggest that in liver cirrhosis the altered BCAA/AAA ratio may influence the altered basal GH secretion and the paradoxical GH response to the OGTT, probably by an increase of adrenergic mediators in the brain. Moreover, the increase of BCAA/AAA ratio seems to be able to abolish the GH paradoxical response to the OGTT.

Adult↗
PubMed1998

Isolation of seven unique biogenic amine receptor clones from the honey bee by library scanning.

The biogenic amine receptor genes constitute an ancient and highly divergent family within the larger superfamily of G-protein-coupled receptors. These receptors play a central role in modulating nerve cell activity and thus behaviour. Because the honey bee offers numerous advantages for behavioural studies we endeavoured to isolate as many members of this gene family as possible from the bee. We compared numerous approaches to gene isolation and found that PCR amplification from small subfractions of cDNA or genomic DNA libraries enabled us to isolate clones that are otherwise undetectable. In total we isolated seven biogenic amine receptor clones and identified five additional related sequences by low-stringency Southern hybridization. Two clones, AmBAR4 and AmBAR6, are 84% and 72% identical to the Drosophila 5-HT2 and D1b receptors, respectively, and probably represent orthologous genes. Phylogenetic analysis indicates that AmBAR5 clusters loosely with a variety of tyramine and octopamine receptors with which it shares <66% identity. The other four clones, AmBAR1, AmBAR2, AmBAR3 and AmBAR7, are weakly to moderately related (28-45% identical) to Drosophila dopaminergic or mammalian adrenergic receptors and probably represent receptors of these classes whose orthologues have not previously been isolated from any insect. The honey bee clones expand the size of the known insect biogenic amine receptor gene family to sixteen members. Therefore the size of the biogenic amine receptor gene family of insects approaches that of vertebrates. This is true despite the reduced behavioural and genetic complexity of the insects relative to vertebrate animals.

Amino Acid Sequence↗
PubMed1979

Overnight sleep EEG and cerebrospinal fluid monoamines in seizures induced by movement.

Clinical, electrical and biochemical studies in an eight years old boy with movement-induced seizures were reported. The attack was usually triggered by sudden initiation of movement, but rarely occurred without any apparent movement. Repeated jumping provoked attacks constantly, which was recorded cinematographically. No abnormality was found either in ictal or interictal EEGs. Haloperidol aggravated the condition, but 1-DOPA had no effect, while DPH (100 mg/day) controlled attacks perfectly with the serum DPH concentration of just 2.0 ug/dl. In overnight sleep analysis, sleep rhythms and characters of REM sleep were not differed significantly from the standard. After DPH therapy, stabilization of sleep in general was noticed; that is, total sleep time prolonged, number of sleep stages decreased and interrupting awakening disappeared. Probenecid loading test revealed that 5-HIAA was normal, HVA high, and large amount of octopamine was detected in CSF.

Child↗
PubMed2001

Trace amines: identification of a family of mammalian G protein-coupled receptors.

Tyramine, beta-phenylethylamine, tryptamine, and octopamine are biogenic amines present in trace levels in mammalian nervous systems. Although some "trace amines" have clearly defined roles as neurotransmitters in invertebrates, the extent to which they function as true neurotransmitters in vertebrates has remained speculative. Using a degenerate PCR approach, we have identified 15 G protein-coupled receptors (GPCR) from human and rodent tissues. Together with the orphan receptor PNR, these receptors form a subfamily of rhodopsin GPCRs distinct from, but related to the classical biogenic amine receptors. We have demonstrated that two of these receptors bind and/or are activated by trace amines. The cloning of mammalian GPCRs for trace amines supports a role for trace amines as neurotransmitters in vertebrates. Three of the four human receptors from this family are present in the amygdala, possibly linking trace amine receptors to affective disorders. The identification of this family of receptors should rekindle the investigation of the roles of trace amines in mammalian nervous systems and may potentially lead to the development of novel therapeutics for a variety of indications.

Amino Acid Sequence↗
PubMed1979

Reactions of cysteamine and other amine metabolites with glyoxylate and oxygen catalyzed by mammalian D-amino acid oxidase.

Pig kidney D-amino acid oxidase [D-amino-acid:oxygen oxidoreductase (deaminating), EC 1.4.3.3] catalyzes a rapid uptake of oxygen when high concentrations (50-100 mM) of glyoxylate and the following amines are present under usual assay conditions (pH 8.3): cysteamine, 2-aminoethanol, putrescine, D,L-1-amino-2-propanol, D,L-2-amino-1-propanol, 3-amino-1-propanol, D,L-octopamine, ethylenediamine, and L-cysteine ethyl ester. Notable physiological amines that do not support a rapid O2 reaction under the above conditions include histamine, serotonin, epinephrine, norepinephrine, spermidine, spermine, and cadaverine. A more detailed kinetic investigation of the reactions involving the first four reactive amines listed above indicated that the cysteamine reaction proceeds at a rapid rate even when cysteamine and glyoxylate are present at less than millimolar concentrations, but greater than millimolar concentrations are needed in the other amine reactions in order to observe a reasonable rate. At low concentrations and pH 7.4, the cysteamine-glyoxylate substrate (presumably thiazolidine-2-carboxylic acid) reacts an order of magnitude faster than any other known D-amino acid oxidase substrate. Considerable circumstantial evidence suggests that the reaction involving cysteamine is occurring physiologically, but the reactions of other amines would be occurring in the cell at a very low rate, if at all. It is proposed that the product of the enzymic reaction may be a metabolic effector that can modify the reactivity of proteins or nucleic acids by covalent attachment.

Amines↗
PubMed1983

Stimulation of blowfly feeding behavior by octopaminergic drugs.

Adult blowflies (Phormia regina Meigen) injected with the octopaminergic drug demethylchlordimeform (10 mug per fly) exhibited enhanced proboscis extension responses when their tarsae were touched to water or aqueous sucrose. They drank more water than saline-injected control flies did but the quantity imbibed was within the normal fluid intake capacity. They became grossly hyperphagic when offered 1 M sucrose, doubling (and in some cases even tripling) their initial body weights. Three other drugs enhanced tarsal responsiveness and induced hyperphagia: DL-octopamine, clonidine (which is known to stimulate octopaminergic receptors in insects), and pargyline, a monoamine oxidase inhibitor. Yohimbine, an antagonist of one class of octopaminergic receptor in insects, prevented the hyperphagia induced by all four drugs. Dopamine, 5-hydroxytryptamine, and DL-norepinephrine failed to cause hyperphagia. These results suggest that octopaminergic receptors in the nervous system of the blowfly positively modulate feeding and drinking behavior.

Journal Article↗
PubMed1986

Light paired with serotonin mimics the effect of conditioning on phototactic behavior of Hermissenda.

A conditioning procedure consisting of pairing-specific stimulation of the eyes and gravity-detecting statocysts in Hermissenda results in a long-term modification of normal positive phototactic behavior. The learning is expressed by a significant suppression of the initiation of locomotion in the presence of light. We now report that an analogue of the classical conditioning procedure, consisting of light paired with serotonin (5-HT) applied directly to the exposed circumesophageal nervous system of otherwise intact animals, mimics the effect of conditioning on long-term changes in phototactic behavior. The effect of the conditioning analogue on behavior shows some specificity with 5-HT since light paired with dopamine or octopamine does not significantly affect phototactic behavior. The conditioning analogue exhibits pairing specificity since unpaired light and 5-HT and 5-HT applied in the dark do not produce behavioral suppression. Animals that initially received unpaired light and 5-HT do show behavioral suppression after receiving paired light and 5-HT. These results indicate that light (the conditioned stimulus) paired with the putative transmitter of the unconditioned stimulus pathway (5-HT) is sufficient to produce long-term phototactic suppression.

Analysis of Variance↗
PubMed1991

Stimulation of pheromone biosynthesis in the moth Helicoverpa zea: action of a brain hormone on pheromone glands involves Ca2+ and cAMP as second messengers.

Isolated abdomen and pheromone gland bioassays were utilized to determine the physiological action of the pheromone-biosynthesis-activating neuropeptide (PBAN) in the corn earworm moth Helicoverpa (= Heliothis) zea. An isolated pheromone gland bioassay showed that synthetic PBAN was active at 0.02 pmol, with maximal activity occurring at 0.5 pmol and 60 min of incubation. Second-messenger studies demonstrated that extracellular Ca2+ is necessary for PBAN activity on isolated pheromone glands. The Ca2+ ionophore A23187 stimulated pheromone biosynthesis alone, whereas the Ca2+ channel blockers La3+ and Mn2+ inhibited PBAN activity. However, the organic Ca2+ channel blockers verapamil and nifedipine did not inhibit PBAN activity. Both forskolin and two cAMP analogues stimulated pheromone biosynthesis in the absence of extracellular Ca2+, indicating that Ca2+ may activate an adenylate cyclase. The biogenic amine octopamine did not elicit pheromone production in isolated gland or abdomen bioassays or when injected into intact female moths. Removal of the ventral nerve chord, including the terminal abdominal ganglia in isolated abdomens, did not affect PBAN stimulation of pheromone production. Similar levels of stimulation were found when isolated abdomens were treated with PBAN in scotophase or photophase.

Journal Article↗
PubMed1994

Cloning, expression, and localization of a chloride-facilitated, cocaine-sensitive serotonin transporter from Drosophila melanogaster.

We report here on the isolation and characterization of a serotonin (5HT) transporter from Drosophila melanogaster. A 3.1-kb complementary DNA clone (dSERT) was found to encode a protein of 622 amino acid residues with a predicted molecular mass of approximately 69 kDa and a putative transmembrane topology characteristic of cloned members of the mammalian Na+/Cl- neurotransmitter cotransporter gene family. dSERT displays highest overall amino acid sequence identity with the mammalian 5HT (51%), norepinephrine (47%), and dopamine (47%) transporters and shares with all transporters 104 absolutely conserved amino acid residues. Upon transient expression in HeLa cells, dSERT exhibited saturable, high-affinity, and sodium-dependent [3H]5HT uptake with estimated Km and Vmax values of approximately 500 nM and 5.2 x 10(-18) mol per cell per min, respectively. In marked contrast to the human SERT (hSERT), 5HT-mediated transport by dSERT was not absolutely dependent on extracellular Cl-, while the sodium-dependent uptake of 5HT was facilitated by increased extracellular Cl- concentrations. dSERT displays a pharmacological profile and rank order of potency consistent with, but not identical to, mammalian 5HT transporters. Comparison of the affinities of various compounds for the inhibition of 5HT transport by both dSERT and hSERT revealed that antidepressants were 3- to 300-fold less potent on dSERT than on hSERT, while mazindol displayed approximately 30-fold greater potency for dSERT. Both cocaine and RTI-55 inhibited 5HT uptake by dSERT with estimated inhibition constants of approximately 500 nM, while high concentrations (> 10 microM) of dopamine, norepinephrine, octopamine, tyramine, and histamine failed to inhibit transport. In situ hybridization reveals the selective expression of dSERT mRNA to specific cell bodies in the ventral ganglion of the embryonic and larval Drosophila nervous system with a distribution pattern virtually identical to that of 5HT-containing neurons. The dSERT gene was mapped to position 60C on chromosome 2. The availability of the gene encoding the unique ion dependence and pharmacological characteristics of dSERT may allow for identification of those amino acid residues and structural motifs that confer the pharmacologic specificity and genetic regulation of the 5HT transport process.

Amino Acid Sequence↗