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At least 343 records · Page 19Linked to original sources
PubMed1984

Regulation of neurohormone release in the fiddler crab, Uca pugilator: effects of gamma-aminobutyric acid, octopamine, Met-enkephalin, and beta-endorphin.

Gamma-aminobutyric acid (GABA) blocked concentration of the pigments in melanophores and erythrophores of intact crabs. GABA blocked the release of pigment concentrating hormones from the isolated eyestalk. Octopamine (OA) blocked black pigment dispersion in intact crabs, but did not affect red pigment dispersion or concentration. OA blocked the release of black pigment dispersing hormone from isolated eyestalks. Met-enkephalin, but not Leu-enkephalin, stimulated black and red pigment concentration in intact crabs. Met-enkephalin, but not Leu-enkephalin, stimulated the release of pigment concentrating hormones from isolated eyestalks. Naloxone blocked the effects of Met-enkephalin in intact crabs and on isolated eyestalks. Beta-endorphin induced black pigment dispersion in intact crabs and in isolated legs.

Animals↗
PubMed1985

A new approach to the analysis of complex dose-response relationships: a multivariate study of octopamine action on the leech Leydig neurone.

Octopamine (OA) hyperpolarizes leech Leydig neurones but response amplitudes and thresholds vary. Associations between response, OA dose and other variables [initial resting potential, action potential (AP) frequency and amplitude, temperature, microelectrode resistance, position of ganglion along nerve cord, animal, treatment order] were examined using canonical correlation. A complex response was expressed by summing changes in membrane potential and AP frequency over 2 min of OA treatment. Only dose and ganglion position influenced this response. One significant canonical variate related dose to immediate changes in membrane potential and summed changes in AP frequency throughout the OA effect. Response to OA was greater in cells in posterior ganglia.

Action Potentials↗
PubMed1987

Octopamine action on the contractile system of crustacean skeletal muscle.

1. In the opener muscle of walking legs of crayfish (Astacus leptodactylus) octopamine (OA) greatly enhances the contractions resulting from brief applications of L-glutamate or of elevated K-concentrations. Synephrine is as effective as OA. 2. In the case of potentiation of responses to high-K applications a presynaptic component of the OA action was excluded by first desensitising the muscle fibres to the action of the natural transmitter, using a high concentration (1 mM) of glutamate. 3. The Ca-antagonists Co, Ni and Mn (1 mM) reduced the effects of glutamate and of elevated K to about one-half. In preparations treated with OA, the same Ca-antagonists also depressed the potentiated contractural responses to glutamate and to elevated K, again to about one-half. 4. OA also enhanced contractions resulting from the application of caffeine. 5. With 5-hydroxytryptamine (5-HT) application, the same postsynaptic effects were obtained as described for OA, except that the 5-HT actions were much weaker. 6. With OA, maximal effects were obtained with concentrations of 5 x 10(-6)-10(-5) M; maximally effective concentrations of 5-HT were around 10(-5) M. 7. The lowest effective concentrations of OA were around 10(-8) M; those of 5-HT were around 10(-7) M. 8. In the same preparation, 5-HT is far more effective in enhancing transmitter release (presynaptic action) than OA, the lowest effective concentration being around 10(-11) M while no presynaptic effects of OA were seen at concentrations below 10(-8) M, in some cases even below 10(-5) M.

Animals↗
PubMed1988

An analysis of the inhibitory responses of dopamine and octopamine on Helix central neurons.

1. Electrophysiological recordings were made from identified neurons in the isolated suboesophageal ganglionic mass of Helix aspersa. Cells were voltage clamped at testing membrane potential. 2. Bath addition of 1 microM dibutyryl cAMP caused a time dependent enhancement of an evoked IPSP and the dopamine (DA) and octopamine (OA) induced outward currents obtained in these neurons. Forskolin, 0.1 microM, which enhances and MDL 12,330A, 0.12 microM, which depresses adenylate cyclase activity also modified these responses. 3. The DA and OA inhibitory responses were both shown to be potassium mediated events. They were preferentially antagonised by low micromolar concentrations of 4-aminopyridine. Two other potassium channel antagonists, tetraethylammonium and apamin had little effect on the DA and OA responses. 4. Cell sensitivity to DA and OA was greatly enhanced in calcium free/2 mM cobalt Ringer. The reversal potential of the DA response was shifted to a more negative value in calcium free Ringer. Sodium free Ringer was also found to alter the responses to DA or OA but those results were not consistent.

4-Aminopyridine↗
PubMed1989

Modulation of swimming activity in the medicinal leech by serotonin and octopamine.

1. The monoamines serotonin (5-HT) and octopamine (OA) enhance the expression of swimming activity in the medicinal leech (Willard, 1981; Belanger and Orchard, 1988). We explored further the effects of these monoamines and related agents on swimming activity observed in isolated leech nerve cords. 2. We confirmed that swimming activity is induced reversibly following exposure of the nerve cord to 5-HT (50 microM); the half-maximal rate of swimming activity develops in about 15 min. Swimming activity returns to control levels about 30 min after drug washout. 3. Swim-induction by 5-HT is blocked by the presence of 10 microM cyproheptadine (a 5-HT antagonist). 4. Although apparently less effective than 5-HT, OA application to nerve cords also induced swimming activity. 5. Depletion of endogenous amines from nerve cords by acute exposure to reserpine (10-150 microM) blocked stimulus-evoked swimming activity within 4 hr. 6. Subsequent application of 5-HT (50 microM) or OA (100 microM) reinstated stimulus-evoked swimming and induced repeated episodes of non-triggered swimming activity. 7. Application of cAMP and cAMP analogs, as well as phosphodiesterase inhibitors (theophylline and IBMX), mimicked the effects of the monoamines, suggesting that 5-HT and OA may activate swimming activity by increasing neuronal cAMP. 8. We obtained episodes of swim-like activity from individual, isolated ganglia exposed to 5-HT or OA. Such episodes were usually brief, with variable cycle period. 9. We conclude that individual nerve cord ganglia contain the complete neuronal circuitry required to generate the rudiments of swimming activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Selective synthesis of racemic 1-11C-labelled norepinephrine, octopamine, norphenylephrine and phenylethanolamine using [11C]nitromethane.

A new and simple method for the selective condensation of no-carrier-added [11C]nitromethane (1) with various substituted (protected) benzaldehydes to [beta-11C]beta-nitrophenethyl alcohols was developed. This method which utilizes tetrabutylammonium fluoride in THF as a catalyst gave a condensation yield of 80-90% and a selectivity of 80-90% for [11C]nitroalcohol vs [11C]nitrostyrene formation within 2 min. Reduction of these [11C]nitroalcohols with Raney nickel in formic acid gave the corresponding [11C]aminoalcohols in a yield of 60-90%. Boron tribromide was used for the cleavage of 4-methoxy and 3,4-(methylenedioxy) phenol protecting groups. After HPLC-purification, racemic 1-11C-labelled norepinephrine (7), phenylethanolamine (4), norphenylephrine (5) and octopamine (6) were prepared in a 12-30% decay corrected total radiochemical yield (20-50% counted from 1) with an overall synthesis time of 40-70 min from end of bombardment (EOB). The radiochemical purity was > 98% and the specific radioactivity 700-1500 Ci/mmol (26-56 GBq/mumol).

2-Hydroxyphenethylamine↗
PubMed2006

Determination of octopamine, synephrine and tyramine in Citrus herbs by ionic liquid improved 'green' chromatography.

Without adding any volatile organic solvents, aqueous solutions of room temperature ionic liquids (RTILs) were used as 'green' mobile phases to determine octopamine, synephrine and tyramine by liquid chromatography. The problems of the adrenergic amines separation, such as band tailing, low retention and low resolution were solved successfully by using RTIL. The effect of 1-ethyl-3-methylimidazolium tertafluoroborate ([EMIM][BF4]) was the best in the six investigated RTILs. The concentration of [EMIM][BF4], mobile phase pH and column temperature, which influenced the chromatographic behaviors of the analytes, were investigated in detail. The change of retention factors caused by pH shift was obviously suppressed by [EMIM][BF4]. The sensitivity, accuracy and repeatability of this method were found to be satisfactory. The contents of adrenergic amines in several Citrus herbs and extracts, such as Fructus aurantii immaturus, were simultaneously determined by this 'green' chromatographic method.

Adrenergic alpha-Agonists↗
PubMed2003

Comparative receptor surface analysis of octopaminergic antagonists for the locust neuronal octopamine receptor.

In drug discovery, it is common to have measured activity data for a set of compounds acting upon a particular protein but not to have knowledge of the three-dimensional structure of the protein active site. In the absence of such three-dimensional information, one can attempt to build a hypothetical model of the receptor site that can provide insight about receptor site characteristics. Such a model is known as a comparative receptor surface analysis (CoRSA) model, which provides compact and quantitative descriptors which capture three-dimensional information about a putative receptor site. The quantitative structure-activity relationship (QSAR) of a set of 20 antagonists for octopamine (OA) receptor 3 in locust nervous tissue, was analyzed using CoRSA. Three-dimensional energetics descriptors were calculated from receptor surface model (RSM)-ligand interaction and these three-dimensional descriptors were used in QSAR analysis. The predictive character of the QSAR was further assessed using 24 agonists for OA receptor as test molecules. An RSM was generated using some subset of the most active structures and the results provided useful information in the characterization and differentiation of OA receptor.

Animals↗
PubMed2006

The cloning of one putative octopamine receptor and two putative serotonin receptors from the tobacco hawkmoth, Manduca sexta.

Serotonin and octopamine (OA) are biogenic amines that are active throughout the nervous systems of insects, affecting sensory processing, information coding and behavior. As an initial step towards understanding the modulatory roles of these amines in olfactory processing we cloned two putative serotonin receptors (Ms5HT1A and Ms5HT1B) and one putative OA (MsOAR) receptor from the moth Manduca sexta. Ms5HT1A and Ms5HT1B were both similar to 5HT1-type receptors but differed from each other in their N-terminus and 3rd cytoplasmic loop. Ms5HT1A was nearly identical to a serotonin receptor from Heliothis virescens and Ms5HT1B was almost identical to a serotonin receptor from Bombyx mori. The sequences for homologs of Ms5HT1A from B. mori and Ms5HT1B from H. virescens were also obtained, suggesting that the Lepidoptera likely have at least two serotonin receptors. The MsOAR shares significant sequence homology with pharmacologically characterized OA receptors, but less similarity to putative OA/tyramine receptors from the moths B. mori and H. virescens. Using the MsOAR sequence, fragments encoding putative OA receptors were obtained from B. mori and H. virescens, suggesting that MsOAR is the first OA receptor cloned from a lepidopteran.

Amino Acid Sequence↗
PubMed2004

Modulation of sensory-CNS-motor circuits by serotonin, octopamine, and dopamine in semi-intact Drosophila larva.

We have introduced an in-situ preparation to induce motor unit activity by stimulating a sensory-CNS circuit, using the third instar larvae of Drosophila melanogaster. Discrete identifiable motor units that are well defined in anatomic and physiologic function can be recruited selectively and driven depending on the sensory stimulus intensity, duration, and frequency. Since the peripheral nervous system is bilaterally symmetric to coordinate bilateral symmetric segmental musculature patterns, fictive forms of locomotion are able to be induced. Monitoring the excitatory postsynaptic potentials (EPSP) on the prominent ventral longitudinal body wall muscles, such as m6 and m12, provides additional insight into how the selective motor units might be recruited within intact animals. We also introduce the actions of the neuromodulators (serotonin, octopamine (OA) and dopamine (DA)) on the inducible patterns of activity within the sensory-motor circuit. The powerful genetic manipulation in Drosophila opens many avenues for further investigations into the circuitry and cellular aspects of pattern generation and developmental issues of circuitry formation and maintenance in the model organism.

Animals↗
PubMed1981

Simultaneous radioenzymatic determination of phenylethylamine, phenylethanolamine, tyramine and octopamine in plasma of patients with hepatic encephalopathy.

A sensitive radioenzymatic assay for the simultaneous determination of phenylethylamine, phenylethanolamine, tyramine and octopamine in plasma samples is reported. After extraction with ethanol, the amines are subjected to enzymatic N-methylation with labelled S-adenosylmethionine, preceded in the case of phenylethylamine and of tyramine, by an enzyme-catalyzed beta-hydroxylation step. The procedure is completed by extraction with toluene containing different amounts of isoamylalcohol, followed by controlled evaporation of the solvent. A generalized and highly significant increase in the concentration of all the four amines was found in plasma samples from patients suffering from hepatic encephalopathy.

Ethanolamines↗
PubMed2003

Synaptic facilitation by ectopic octopamine and 5-HT receptors in Aplysia.

The cAMP pathway plays a critical role in synaptic plasticity. We assessed using the ectopic expression of octopamine (OA) receptor, the contribution of the cAMP pathway to short-term facilitation of sensory-motor synapses in Aplysia. When synaptic connections were depressed to 20-30% of their initial EPSP amplitude, the application of OA to sensory cells expressing OA receptor showed significant synaptic facilitation, but this was less than the synaptic facilitation shown by 5-HT treatment. We also found that synaptic facilitation was further enhanced when OA was treated in the presence of 5-HT at non-depressed synapses, but not at depressed synapses. These results imply that the role of cAMP in synaptic facilitation is reduced as the synapse becomes depressed due to repeated activity.

Adrenergic alpha-Agonists↗
PubMed1983

Rapid estimation of catecholamines, octopamine and 5-hydroxytryptamine in biological tissues using high-performance liquid chromatography with coulometric detection.

A rapid, convenient procedure is described for the simultaneous determination of catecholamines, monohydroxyphenolamines and 5-hydroxytryptamine in biological tissues. The procedure involves homogenization of tissue in perchloric acid, addition of heparin and centrifugation followed by direct injection of the supernatant onto a C18 reversed-phase high-performance liquid chromatographic column. The mobile phase employed sodium dodecyl sulfate as ion pair reagent with 20% acetonitrile and 10-12% methanol as organic modifier. Eluted fractions were detected electrochemically using dual coulometric electrodes operated in screen mode. The procedure has been applied to the analysis of norepinephrine, epinephrine, dopamine, octopamine, tyramine, 5-hydroxytryptamine and tryptophan in a variety of tissues including mammalian heart and brain and insect nerve cord.

Animals↗
PubMed2002

A high-affinity octopamine transporter cloned from the central nervous system of cabbage looper Trichoplusia ni.

A cDNA encoding a high-affinity Na(+)/anion(-)-dependent octopamine transporter (OAT) was isolated via an RT-PCR-based approach from caterpillars of the cabbage looper, Trichoplusia ni. The deduced amino acid sequence of the OAT cDNA predicts a 670 amino acid protein bearing strong homology to previously cloned monoamine transporters. The expression pattern of OAT mRNA in the central nervous system revealed by in situ hybridization closely resembles that of OA-ergic neurons identified by the presence of mRNA for tyramine beta-hydroxylase, a marker enzyme for OA-ergic neurons in invertebrates. In vitro, insect cells infected with OAT-expressing baculovirus accumulated both (3)H-OA and (3)H-dopamine with saturation kinetics typical of carrier-mediated processes. (3)H-dopamine uptake by OAT was most inhibited by tyramine, OA, dopamine and the tricyclic antidepressants desipramine and imipramine. Substitution studies for Na(+) and Cl(-) indicate that OAT has a strong requirement for Na(+) and a less stringent requirement for Cl(-). The pharmacological profile of OAT is distinct from those of other cloned monoamine transporters and makes OAT a potential target for neuro-active pest control agents.

Adrenergic alpha-Agonists↗
PubMed2002

Three-dimensional common-feature hypotheses for octopamine agonist 2-(arylimino)imidazolidines.

Three-dimensional pharmacophore hypotheses were built from a set of 10 octopamine (OA) agonist 2-(Arylimino)imidazolidines (AIIs), 2-(Arylimino)thiazolidines (AITs) and 2-(Arylimino)oxazolidines (AIOs). Among the 10 common-featured models generated by program Catalyst/HipHop, a hypothesis including a ring aromatic (RA), a positive ionizable (PI) and three hydrophobic aliphatic (HpAl) features was considered to be important in evaluating the OA-agonist activity. Active OA agonist 2,6-Et2 AII mapped well onto all the RA, PI and HpAl features of the hypothesis. On the other hand, less active compounds were shown to be difficult to achieve the energetically favorable conformation which is found in the active molecules in order to fit the 3-D common-feature pharmacophore models. Taken together, 2,6-Et2-Ph and foramidine structures are important as OA agonists. The present studies on OA agonists demonstrate that a RA, a PI and three HpAl sites located on the molecule seem to be essential for OA-agonist activity.

Animals↗
PubMed2002

Three-dimensional common-feature hypotheses for octopamine agonist arylethanolamines.

Three-dimensional pharmacophore hypotheses were built from a set of 12 octopamine (OA) agonist arylethanolamines (AEAs). Among the 10 common-featured models generated by program catalyst/HipHop, a hypothesis including a hydrogen-bond donor (HBD) and a hydrogen-bond acceptor lipid (HBA1) features was considered to be important in evaluating the OA activity. OA mapped well onto all the HBD and HBA1 features of the hypothesis. On the other hand, for some inactive compounds, their lack of affinity is primarily due to their inability to achieve an energetically favorable conformation shared by the active compounds. Taken together, structures of a 4-OH-Ph, alpha-OH, and a primary amine are important for OA activities. The present studies on OA agonists demonstrate that an HBD and an HBA1 sites located on the molecule seem to be essential for OA activity.

Adrenergic alpha-Agonists↗
PubMed1999

Three-dimensional pharmacophore hypotheses of octopamine receptor responsible for the inhibition of sex-pheromone production in Helicoverpa armigera.

Three-dimensional pharmacophore hypotheses were built on the basis of a set of nine octopamine (OA) agonists responsible for the inhibition of sex-pheromone production in Helicoverpa armigera. Of the 10 models generated by the program Catalyst/Hypo, hypotheses including hydrogen-bond acceptor (HBA), hydrophobic (Hp), and hydrophobic aliphatic (HpAl) features were considered important and predictive in evaluating OA agonists. An HBA and four hydrophobic features are the minimum components of an effective OA agonist-binding hypothesis, which resembles the results of binding activity to locust OAR3. Active agonists mapped well onto all of the features of the hypothesis, such as HBA, Hp, and HpAl features. On the other hand, inactive compounds lacking binding affinity were shown to be poorly capable of achieving an energetically favorable conformation shared by the active molecules in order to fit the 3D chemical feature pharmacophore models. Those hypotheses are considered useful in designing new leads for more active compounds. Further research on the comparison of models from agonists may help elucidate the mechanisms of OA receptor-ligand interactions.

Animals↗
PubMedDate not supplied

Three-dimensional molecular field analyses of octopaminergic agonists and antagonists for the locust neuronal octopamine receptor class 3.

The quantitative structure-activity relationship (QSAR) of a set of 70 octopaminergic agonists and 20 antagonists against octopamine receptor class 3 (OAR3) in locust nervous tissue was analyzed by molecular field analysis (MFA). MFA of these compounds evaluated effectively the energy between a probe and a molecular model at a series of points defined by a rectangular grid. Contour surfaces for the molecular fields are presented. These results provide useful information in the characterization and differentiation of octopaminergic receptor types and subtypes.

Animals↗