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PubMed1975

Synthesis of octopamine by insect dorsal median unpaired neurons.

Dorsal unpaired median (DUM) neurons of locusts and grasshoppers inhibit the instrinsic rhythm of contraction of metathoracic extensor tibia muscle fibers. This physiological action is mimicked by very low concentrations of octopamine and by higher concentrations of dopamine and noradrenaline. We have examined the synthesis of biogenic amines from tritiated tyrosine by these neurons. DUM cell bodies and a peripheral nerve containing the DUM axon which terminates in the extensor tibia both produced octopamine, but neither noradrenaline nor dopamine synthesis was detected. The observations support the suggestion that the dorsal unpaired median neurons are octopaminergic.

Animals↗
PubMed1979

Neural control of light emission in Photuris larvae: identification of octopamine-sensitive adenylate cyclase (1).

Octopamine, a putative phenylethylamine neurotransmitter present in the firefly, has been found to be a potent stimulator of cyclic AMP synthesis in the larval light organ. In the same tissue, octopamine causes a small inhibition of phosphodiesterase activity. Because of the relatively simple anatomical relationships present in the larval light organ, compared with that of the adult, this preparation should offer an attractive model for studying the biochemistry of neurohumoral control of light emission.

Adenylyl Cyclases↗
PubMed2003

Hygienic behavior in the honey bee (Apis mellifera L.) and the modulatory role of octopamine.

Honey bees, Apis mellifera, which perform hygienic behavior, quickly detect, uncap and remove diseased brood from the nest. This behavior, performed by bees 15-20 days old and prior to foraging, is likely mediated by olfactory cues. Because the neuromodulator octopamine (OA) plays a pivotal role in olfactory-based behaviors of honey bees, we examined whether bees bred for hygienic and nonhygienic behavior differed with regard to their OA expression and physiology. We compared the staining intensity of octopamine-immunoreactive (OA-ir) neurons in the deutocerebral region of the brain, medial to the antennal lobes, between hygienic and nonhygienic bees (based on genotype and phenotype). We also tested how the olfactory responses of the two lines, based on electroantennograms (EAGs), were affected by oral administration of OA and of epinastine, a highly specific OA antagonist. Our results revealed that bees expressing hygienic behavior (irrespective of genotype) possessed OA-ir neurons that exhibited more intense labeling than same-aged bees not performing the behavior. In bees bred for nonhygienic behavior, OA significantly increased the EAG response to low concentrations of diseased brood odor. Conversely, in bees bred for hygienic behavior, epinastine significantly reduced the magnitude of the EAG response, a reduction not observed in nonhygienic bees. Our results provide two lines of evidence that OA has the potential to facilitate the detection and response of honey bees to diseased brood. We discuss the contributions of OA for behavioral shaping and its ability to bias the nervous system to express one form of behavior over another.

Adrenergic alpha-Agonists↗
PubMed2005

A splice variant of the Drosophila vesicular monoamine transporter contains a conserved trafficking domain and functions in the storage of dopamine, serotonin, and octopamine.

Vesicular monoamine transporters (VMATs) mediate the transport of dopamine (DA), serotonin (5HT), and other monoamines into secretory vesicles. The regulation of mammalian VMAT and the related vesicular acetylcholine transporter (VAChT) has been proposed to involve membrane trafficking, but the mechanisms remain unclear. To facilitate a genetic analysis of vesicular transporter function and regulation, we have cloned the Drosophila homolog of the vesicular monoamine transporter (dVMAT). We identify two mRNA splice variants (DVMAT-A and B) that differ at their C-terminus, the domain responsible for endocytosis of mammalian VMAT and VAChT. DVMAT-A contains trafficking motifs conserved in mammals but not C. elegans, and internalization assays indicate that the DVMAT-A C-terminus is involved in endocytosis. DVMAT-B contains a divergent C-terminal domain and is less efficiently internalized from the cell surface. Using in vitro transport assays, we show that DVMAT-A recognizes DA, 5HT, octopamine, tyramine, and histamine as substrates, and similar to mammalian VMAT homologs, is inhibited by the drug reserpine and the environmental toxins 2,2,4,5,6-pentachlorobiphenyl and heptachlor. We have developed a specific antiserum to DVMAT-A, and find that it localizes to dopaminergic and serotonergic neurons as well as octopaminergic, type II terminals at the neuromuscular junction. Surprisingly, DVMAT-A is co-expressed at type II terminals with the Drosophila vesicular glutamate transporter. Our data suggest that DVMAT-A functions as a vesicular transporter for DA, 5HT, and octopamine in vivo, and will provide a powerful invertebrate model for the study of transporter trafficking and regulation.

Adrenergic Uptake Inhibitors↗
PubMed1989

The effect of serotonin and octopamine on the optokinetic response of the crab Leptograpsus variegatus.

A standard optokinetic response of the ipsilateral and contralateral (driven) eyes of the crab Leptograpsus variegatus to a sinusoidally oscillating striped drum was established. Optokinetic responses were then measured of animals that had been treated by introducing serotonin and octopamine into the blood stream via the heart and also into the neural tissue of the optic lobes via a micropipette. Both serotonin and octopamine enhance the optokinetic effect when applied in low doses. Experiments show that serotonin is most likely acting closer to the sensory input in the optokinetic system.

Animals↗
PubMed1996

Modulation of antennal scanning in the honeybee by sucrose stimuli, serotonin, and octopamine: behavior and electrophysiology.

Antennal motor activity of the honeybee was used to test the effects of sucrose stimuli and of serotonin and octopamine microinjections into the brain. The antennal scanning behavior was analyzed in behavioral experiments. Activity of an antennal muscle, the "fast pedicellus flexor muscle" which dominates scanning behavior, was used as a physiological measure of modulatory effects. A single sucrose stimulus applied to both the antenna and the proboscis leads to significant increases of the frequency of antennal scanning compared to those of untreated controls and animals stimulated with water. A single sucrose stimulus applied only to the antenna or the proboscis has no significant behavioral effects. Injection of small volumes (approximately 500 pl) of serotonin (5HT) or octopamine (OA) at concentrations of 10(-5) M into the dorsal lobe, the sensory motor center of the antenna, leads to functionally antagonistic behavioral effects. While 5HT injection significantly reduces the antennal scanning frequency, OA significantly enhances it. The degree of behavioral modulation is significantly correlated with the activity of the animals. In animals which display low scanning activity, OA injection has an enhancing effect, while 5HT has no effect. In contrast, 5HT injection, but not OA injection, produces a behavioral effect in animals with high scanning activity. Behavioral changes and changes of activity of the fast pedicellus flexor muscle are closely correlated. Significant, functionally antagonistic effects of 5HT and OA on muscle activity were found after injections of the compounds into the dorsal lobe. 5HT leads to a reduction of the muscle potential frequency starting immediately after injection and lasting at least 15 min. OA injection results in an increase of frequency, which has its maximum 5 min after injection. The experiments demonstrate that sucrose, the reward stimulus during associative learning in the bee, also modulates motor activity under nonassociative conditions. The similar effects of sucrose stimulation and OA injection are consistent with the hypothesis that OA mediates the effects of sucrose stimuli.

Animals↗
PubMed1986

High sensitivity of brain octopamine levels to stress.

Rats were submitted to unsignalled and uncontrolled electrical shocks. When re-exposed to the same situation but not shocked, 24 h later, their locomotor activity was significantly reduced compared to that of controls. This conditioned suppression was associated with a significant decrease in p-octopamine (OA) in brain stem and hypothalamus. Shocks delivered just before brain fixation produced an even larger decrease in cerebral OA. Heart levels of OA were not affected. Cerebral and peripheral levels of dopamine and noradrenaline were not significantly or reliably affected. These results, as those of previous experiments, suggest that octopamine is involved in emotional, neurovegetative responses to stress.

Animals↗
PubMed1990

Tryptophanyl-tRNA synthetase-like immunoreactivity in the central nervous system and midgut of the migratory locust. Comparisons with gastrin-cholecystokinin-like and octopamine-like immunoreactivity.

A tryptophanyl-tRNA synthetase (TrpRS)-immunoreactivity is localized in various neurosecretory cells of all ganglia of the central nervous system of the Orthoptera Locusta migratoria, except in deutocerebrum, and in endocrine cells of the midgut. It has been observed that TrpRS-like material never co-localizes either with CCK-like or octopamine-like material. TrpRS immunoreactive perikarya and processes that ramify extensively throughout the neuropiles have been detected in the protocerebrum, optic lobes, tritocerebrum, suboesophageal, thoracic and abdominal ganglia. In the lateral protocerebrum, a particular TrpRS pathway different from the lateral gastrin cholecystokinin (CCK-8(s] pathway is revealed, certain of these processes terminating in the glandular part of the corpora cardiaca. In the metathoracic ganglion, have been observed numerous immunoreactive cell bodies and processes in the neuropiles. Some of them constitute a major pathway and which are distinct from octopamine (OA) cells but in close vicinity with the latter. In the midgut immunopositive TrpRS-like cells are dispersed among the regenerative and digestive cells of the epithelium; they are different from gastrin-cholecystokinin positive cells. The various TrpRS-like immunoreactivities identified in Locusta indicate that TrpRS-like material may occur in different tissues of organisms other than Vertebrates. These results suggest also that TrpRS-like enzyme could be involved in functions other than aminoacylation, as in Vertebrates.

Animals↗
PubMed1983

Octopamine and locomotor activity of rats.

Intracerebroventricular administration of P-octopamine (OA) had opposite effects on locomotor activity depending on whether or not the rats were subjected to uncontrollable electric shocks. In unshocked rats, OA produced a large decrease in locomotor activity, but when the rats were subjected to unsignalled and uncontrollable electric shocks, a significant increase in locomotor activity resulted. The latter effect was observed either when the shocks were applied during the measurement of locomotor activity or when they were applied the day before (conditioned suppression paradigm). These results support the hypothesis of a neuromodulation of central noradrenergic transmission by octopamine.

Animals↗
PubMed1989

A concentration-dependent localization of octopamine-sensitive adenylate cyclase activity in locust skeletal muscle.

A concentration-dependent localization of octopamine-sensitive adenylate cyclase activity has been demonstrated in skeletal muscle of the locust, Schistocerca gregaria, using an histochemical technique. In the intermediate speed contracting muscle fibres from the fan region of the extensor-tibiae muscle of the locust hindleg, low concentrations of DL-octopamine (10(-8) M) induce reaction product preferentially in the sarcoplasmic reticular component of the dyads. At slightly higher concentrations (10(-7) and 10(-6) M) lower amounts of diffuse reaction product are also found in the non-dyad sarcoplasmic reticulum and at the sarcolemmal membrane, with occasional amounts of a less diffuse, punctuate product in the transverse tubule (T-tubule) component of the dyads. At higher concentrations (10(-5) and 10(-3) M) the predominant product is the dense, plaque-like accumulations of reaction product in the T-tubule component of the dyads. The results are discussed in terms of the likely physiological significance of the accumulation of reaction product in these different locations.

Adenylyl Cyclases↗
PubMed1986

Trace amines (ethylamine, octopamine, and tryptamine) stimulate inositol phospholipid hydrolysis in rat cerebral cortex slices.

Ethylamine, octopamine, tryptamine, and carbachol stimulate inositol phosphate accumulation in a dose-dependent way in rat cortical slices. Tyramine at 100 microM has no effect. The major inositol phosphate that is accumulated following stimulation is the monophosphate. The effect of carbachol is blocked by atropine but not by cyproheptadine, phenoxybenzamine, haloperidol or propranolol. None of the antagonists tried, including atropine, had an effect on the stimulation caused by ethylamine, octopamine or tryptamine.

Animals↗
PubMed1990

Dopamine and octopamine in whole body extracts of the bulb mite.

Using high performance liquid chromatography with electrochemical detection, whole body extracts of the bulb mite, Rhizoglyphus echinopus (Fumouze and Robin), were found to contain the biogenic amines dopamine and octopamine at concentrations of 4.3 +/- 0.6 and 2.3 +/- 1.4 ng g-1 wet weight, respectively. Adrenaline, noradrenaline, tyramine, N-methyldopamine, N-acetyldopamine, and 5-hydroxytryptamine, if present, were below the limits of detectability. This is the initial demonstration of the presence of octopamine in a mite species.

Animals↗
PubMed1987

Regulation by forskolin of octopamine-stimulated adenylate cyclase from brain of the dipterous Ceratitis capitata.

Forskolin, a diterpene that exerts several pharmacological effects, activates adenylate cyclase in brain and in some other mammalian tissues. Properties of forskolin activation of adenylate cyclase from central nervous system of the dipterous Ceratitis capitata are described. The interaction of forskolin with the insect adenylate cyclase system was studied by evaluating its effect on metal-ATP kinetics, protection against thermal inactivation, membrane fluidity and enzyme modulation by fluoride, guanine nucleotides, octopamine, and ADP-ribosylation by cholera toxin. The diterpene stimulated basal enzyme activity both in membranes and Triton X-100-solubilized preparations, apparently devoid of functional regulatory unit, this effect being rapidly reversed by washing the membranes. An increase of Vmax accounts for the activation of soluble and membrane adenylate cyclase preparations by forskolin, whereas the affinity of the enzyme for the substrate was not affected. Forskolin apparently protects the membrane enzyme from thermal inactivation, and at concentrations that promote the enzyme activity the diterpene does not alter membrane microviscosity. Forskolin does not appear to alter the sensitivity of insect adenylate cyclase to sodium fluoride, guanine nucleotide, or regulatory subunit ADP ribosylated by cholera toxin, the combined effect of these factors with the diterpene resulting in a nearly additive enzymatic activation. However, forskolin blocks the octopamine stimulatory input. Results obtained with the insect adenylate cyclase system are discussed and compared to what is known about mammalian systems to propose a mechanism of enzyme activation by forskolin.

Adenylyl Cyclases↗
PubMed1985

Increased urinary excretion of m-octopamine in neuroblastoma.

The urine of three patients with neuroblastoma was found to have a 3 to 5-fold elevation of m-octopamine concentration. The concentration of m-synephrine was normal in two cases and slightly elevated in the third. These findings were attributed to an increased formation of m-octopamine by this tumor.

2-Hydroxyphenethylamine↗
PubMed1979

Synthesis of dopamine and octopamine in the crustacean stomatogastric nervous system.

The spiny lobster stomatogastric nervous system synthesizes dopamine and octopamine in vitro from exogenous [3H]tyrosine. Each amine accumulates with a specific distribution among 9 separately analyzed regions within the system. Synthesis of other catecholamines was not observed. [3H]Dopamine is found in nerves, ganglia, and identified commissural ganglion cell bodies in which catecholamine histofluorescence has been demonstrated. The biosynthetic and histochemical data together indicate that dopaminergic cells send axons from the commissural ganglia to the stomatogastric ganglion neuropil along the same pathway followed by fibers that activate the pylroic motor network. The results support the hypothesis that dopamine mediates activation of the pyloric system in vivo, as observed in vitro. [3H]Octopamine accumulates primarily in the commissural and stomatogastric ganglia, where it may modulate neuronal activity, but octopaminergic cells and release sites within the stomatogastric system have not been identified.

Animals↗
PubMed1981

Voltage-dependent current evoked by dopamine and octopamine in Aplysia.

Octopamine and dopamine evoke a slow voltage-dependent inward current in neurons of Aplysia. The responses are present only at depolarized potentials (greater than -40 mV). They are insensitive to changes in potassium, persist after removal of sodium, are not reduced by low chloride solution, and are blocked by cadmium. Because of the similarities in voltage-dependence, time course and ionic sensitivities, the ionic mechanism of the voltage-dependent responses to octopamine and dopamine are concluded to be the same as that of the voltage-dependent response to serotonin reported previously.

Animals↗
PubMed1991

Octopamine induces bursting and plateau potentials in insect neurones.

The membrane properties of some inter- and motoneurones in the respiratory and flight systems of the locust Locusta migratoria were characterized during octopamine perfusion by means of intracellular recording techniques. Octopamine induced active membrane properties in these neurones. Plateau-potentials were evoked by brief current pulses or synaptic input in 3 of the identified neurones and endogenous bursting was evoked by prolonged current pulses in one identified interneurone. Hyperpolarizing pulses injected into these neurones either prematurely terminated or suppressed these responses, indicating that these potentials are due to active membrane properties intrinsic to these neurones. Such intrinsic membrane properties have not been described in insects before. Further investigations are necessary to examine whether these properties may play an important role in the generation of rhythmic motor patterns as has previously been demonstrated in many other vertebrate and invertebrate motor systems.

Animals↗