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At least 865 records · Page 48Linked to original sources
PubMed1985

Trace amines inhibit the electrically evoked release of [3H]acetylcholine from slices of rat striatum in the presence of pargyline: similarities between beta-phenylethylamine and amphetamine.

Amphetamine (AMPH) inhibits the electrically evoked release of [3H]acetylcholine (ACh) from rat striatal slices through the activation of inhibitory dopamine receptors. Naturally occurring analogs of amphetamine (AMPH) such as beta-phenylethylamine (beta-PEA), tyramine (TYR) and octopamine (OCT) are present in trace amounts in the brain of several species. We have studied in this model, in comparison with AMPH, the effects of beta-PEA, TYR and OCT, in order to explore if their central effects are mediated through an action involving dopaminergic nerve terminals or whether they activate a specific receptor directly. In contrast to the results obtained with AMPH, in the absence of inhibition of monoamine oxidase activity, the three amines beta-PEA (0.1-10 microM), TYR (0.1-10 microM) and OCT (10 microM) did not affect the electrically evoked release of [3H]ACh. On the other hand, in the presence of pargyline (10 microM), the three amines inhibited the electrically evoked release of [3H]ACh and all subsequent experiments were carried out in the presence of pargyline. After pretreatment with reserpine (5 mg/kg s.c., 24 h), which results in a 95% depletion of the endogenous dopamine content, OCT lost its inhibitory effect on [3H]ACh release, whereas beta-PEA and TYR still inhibited the electrically evoked release of [3H]ACh. Reserpine pretreatment (5 mg/kg s.c., 24 h) combined with alpha-methyl-p-tyrosine (300 mg/kg i.p., 2 h) reduced endogenous dopamine levels by 99.9%, but, under these conditions, beta-PEA, TYR and AMPH still retained their inhibitory effect on [3H]ACh, release. These inhibitory effects of beta-PEA and AMPH on [3H] ACh release were antagonized by S-sulpiride (0.1 microM). In striatal slices from untreated rats, the inhibition of [3H]ACh released by beta-PEA (30 microM), TYR (30 microM) or AMPH (10 microM) was abolished completely after a 6-hydroxydopamine lesion of the nigro-striatal dopaminergic system. The present data indicate that in order to inhibit the release of [3H]ACh from rat striatal slices in vitro, OCT requires the integrity of vesicular stores of dopamine. On the other hand, beta-PEA, TYR and AMPH are still active when the dopamine levels are depleted, although they require the integrity of the dopaminergic nerve terminal. Inhibition of monoamine oxidase is essential to demonstrate the inhibitory effects of exogenous beta-PEA, TYR and OCT on cholinergic transmission. Our results indicate that a hypothesis concerning a possible physiopathological role of endogenous beta-PEA or TYR should involve concomitant changes in monoamine oxidase activity.

Acetylcholine↗
PubMed1982

[Neuroendocrine control of blood lipids in the locust, Locusta migratoria].

In order to determine the best conditions, the influence of various parameters on the haemolymph lipid concentration were studied. These parameters are the age, the sex and the feeding of the animals, the time and the number of the haemolymph sample-taking and the temperature of the locust culture. A large in vivo increase in haemolymph lipid concentration was obtained in locusts which received extracts of the whole CC and of their glandular or neurohemal lobes. Reversely, a decrease in this concentration was obtained in locusts operated 7 days before (cardiacectomy or glandular lobe removal). Moreover the pars intercerebralis extracts increased the level of haemolymph lipids. We conclude that adipokinetic factors are present, both in the glandular lobes of the CC and in their neurohemal lobes. It is likely that the latter partly originate from the pars intercerebralis. Results of allatectomy and injections of corpora allata extracts led to the conclusion that corpora allata contain an adipokinetic factor, the juvenile hormone. and factors that inhibit the haemolymph lipid concentration. Finally, from different injections of neurotransmitters and drugs it is argued that it is mainly octopamine which is involved in the mechanism governing the increase of the level of haemolymph lipids.

Animals↗
PubMedDate not supplied

Pharmacodynamic differentiation of chronotropic and inotropic beta-adrenergic receptors in rabbit heart.

Isolated, perfused rabbit hearts were used to identify substituted phenylethylamines selective for either chronotropic or inotropic stimulation relative to norepinephrine. Heart rate and dF/dtmax were measured; the difference in their normalized values was used as an index of selectivity. p-Octopamine (OA) showed chronotropic preference, while phenylephrine (PE) showed a significant inotropic preference. Their effects were not prevented by reserpine pretreatment, cocaine, butoxamine, or phenoxybenzamine, but were antagonized by propranolol, which suggests that OA and PE exert their selective actions directly at beta 1-receptors. These findings provide further evidence for the existence of separate chronotropic and inotropic beta-adrenergic receptors in the heart.

Animals↗
PubMed1995

Dorsal unpaired median (DUM) neurones with neurohaemal functions in the locust, Locusta migratoria.

Certain members of the class of dorsal unpaired median (DUM) neurones do not only innervate skeletal muscles, but they also establish neurohaemal release sites on the surface of peripheral nerves. These release sites may be associated with well-known neurohaemal organs, but they also occur in other parts of the peripheral nervous system. These DUM neurones are most likely responsible for the release of octopamine into the haemolymph as has been observed in certain behavioural contexts.

Animals↗
PubMed1982

Pathologic synergy in cardiovascular and respiratory compensation with cirrhosis and sepsis. A manifestation of a common metabolic defect?

Multivariable physiologic studies of cardiovascular, respiratory, and metabolic functions were performed in 341 patients (884 studies). Eighty patients had cirrhotic liver disease, 64 had sepsis, 87 had nonseptic cariogenic syndromes, and 110 had nonseptic general surgical or traumatic injury. The group with cirrhosis had the highest cardiac index and ejection fraction. When compared with the group with nonseptic surgery or trauma, vascular tone was reduced in the patients with cirrhosis or sepsis and was lowest in patients with both conditions. Ventricular function was good in the groups with cirrhosis or sepsis, due to the additive effect in reducing vascular tone that allowed ejection fraction to increase, but caused the ratio of alveolar ventilation to perfusion (VA/QT) to fall, resulting in a greater perfusion of a decreased pulmonary vascular bed. The falls in vascular tone and VA/QT in patients with cirrhosis or sepsis result from the reduced oxygen consumption that occurs due to metabolic imbalance (B state). This B state seems to reflect a hepatic inability to metabolize aromatic amino acids, so that levels of tyrosine, phenylalanine, and the false neurotransmitter octopamine increase. These mechanisms are pathologically synergistic when sepsis and cirrhosis occur together.

Amino Acids↗
PubMed1997

Antennal lobe neurons of the honey bee, Apis mellifera, express a D2-like dopamine receptor in vitro.

We have used the D2-specific dopamine receptor ligand spiperone [N-(p-aminophenethyl) spiperone; NAPS] coupled to the fluorophore 7-nitrobenz-2-oxa-1,3-diazole-4-yl (NBD) to visualize dopamine receptors expressed in vitro by neurons of the primary antennosensory centers (antennal lobes) of the brain of the honey bee, Apis mellifera. Changes in the percentage of antennal lobe neurons exhibiting spiperone binding sites over time in culture and at different stages of metamorphic adult development have been investigated. Neurons obtained from animals at all stages of development exhibited spiperone binding sites, but only after 2 days or more in vitro. The percentage of antennal lobe neurons in vitro expressing spiperone binding sites increased significantly with the development of the antennal lobe neuropil. Fluorescently labelled spiperone (120 nM) could be displaced effectively by 1 mM dopamine but not by the same concentration of tyramine, octopamine, or serotonin. In addition, the D2 antagonist spiperone and the D2/D1 antagonist fluphenazine were more effective at displacing the fluorescent ligand than the D1-specific antagonist SCH23390. Our results indicate that Apis antennal lobe neurons in culture express a dopamine receptor and that this receptor is more likely to be D2-like than D1-like in nature. The receptor is expressed early in the metamorphic adult development of the antennal lobe neuropil of the brain.

Animals↗
PubMed1998

Immunocytochemical demonstration of locustatachykinin-related peptides in the central complex of the locust brain.

The central complex, a highly ordered neuropil area in the insect brain, plays a role in motor control and spatial orientation. To further elucidate the neurochemical architecture of this brain area, we have investigated the distribution and morphology of neurons containing locustatachykinin I/II-related substances in the central complex of the locust Schistocerca gregaria. The central complex is innervated by at least 66 locustatachykinin I/II-immunoreactive neurons, which belong to two sets of tangential neurons and four sets of columnar neurons. These neurons give rise to immunostaining in the protocerebral bridge, in several layers of the upper division of the central body, and in all layers except layer 5 of the lower division of the central body. Double-label experiments show colocalization of immunoreactivity for both locustatachykinin I/II and octopamine in tangential neurons of the protocerebral bridge. A pair of tangential neurons of the lower division of the central body exhibits both locustatachykinin I/II and gamma-aminobutyric acid (GABA) immunoreactivity. A set of 16 columnar neurons of the lower division of the central body shows colocalized immunoreactivity for locustatachykinin II, leucokinin, and substance P. This study reveals novel features of the anatomical organization of the locust central complex and suggests a prominent role for locustatachykinin-related peptides as neuromediators and cotransmitters within this brain area.

Animals↗
PubMedDate not supplied

Biogenic amines in the brain of the honeybee: cellular distribution, development, and behavioral functions.

This review provides a summary of the cellular distribution of amine-containing neurons and the organization of aminergic pathways in the brain and suboesophageal ganglion of the honeybee. Neurons synthesizing the biogenic amines serotonin, dopamine, octopamine, and histamine are stained with well-defined polyclonal antisera. Since some of these aminergic neurons are uniquely identifiable, it is possible to follow their morphogenesis during brain development. Pharmacological studies show that aminergic mechanisms are involved in various behavioral modifications including associative learning. The immunocytochemical approach resolves at a single cell level the neural pathways that mediate adaptive behavioral changes.

Adaptation, Physiological↗
PubMed1999

Biogenic amine systems in the fruit fly Drosophila melanogaster.

Biogenic amines are important neuroactive molecules of the central nervous system (CNS) of several insect species. Serotonin (5HT), dopamine (DA), histamine (HA), and octopamine (OA) are the amines which have been extensively studied in Drosophila melanogaster. Each one of the four aminergic neuronal systems exhibits a stereotypic pattern of a small number of neurons that are widely distributed in the fly CNS. In this review, histochemical and immunocytochemical data on the distribution of the amine neurons in the larval and adult nervous system, are summarized. The majority of DA and 5HT neurons are interneurons, most of which are found in bilateral clusters. 5HT innervation is found in the feeding apparatus as well as in the endocrine organ of the larva, the ring gland. The octopaminergic neuronal population consists of both interneurons and efferent neurons. In the larval CNS all OA immunoreactive somata are localized in the midline of the ventral ganglion while in the adult CNS both unpaired neurons and bilateral clusters of immunoreactive cells are observed. One target of OA innervation is the abdominal muscles of the larval body wall where OA immunoreactivity is associated with the type II boutons in the axonal terminals. Histamine is mainly found in all photoreceptor cells where it is considered to be the major neurotransmitter molecule, and in specific mechanosensory neurons of the peripheral nervous system. Similarities between specific aminergic neurons and innervation sites in Drosophila and in other insect species are discussed. In addition, studies on the development and differentiation of 5HT and DA neurons are reviewed and data on the localization of 5HT, DA, and OA receptors are included as well. Finally, an overview on the isolation of the genes and the mutations in the amine biosynthetic pathways is presented and the implications of the molecular genetic approach in Drosophila are discussed.

Animals↗
PubMed1998

Activating properties of cocaine and cocaethylene in a behavioral preparation of Drosophila melanogaster.

The use of Drosophila as a model to study the behavioral consequences of stimulant drugs was analyzed in an active preparation of decapitated Drosophila. Application of cocaine and cocaethylene to discrete nerve cord cells regulating motor programs of behavior produced striking patterns of behavioral activity in a concentration-related manner. In general, intense circling behavior and significant wing buzzing activity were distinguishable behavioral markers in flies treated with mM concentrations of cocaine or cocaethylene. The significant changes in motor behavior induced by stimulant drugs in decapitated flies were not reproduced by the application of apomorphine, a direct dopamine (DA) agonist, or octopamine, a naturally occurring transmitter in arthropods. Because both cocaine and cocaethylene interfere with DA reuptake in mammals, we characterized the role of DA receptors mediating increased stereotypy and motor behavior in flies. Coadministration of SCH-23390, a specific D1 receptor antagonist, significantly attenuated the behavior-activating properties of cocaine and cocaethylene in this active experimental preparation. Therefore, the receptor protein mediating the behavioral responses to stimulant drugs in Drosophila is pharmacologically similar to the mammalian D1 subtype. In rats, cocaine- and cocaethylene-induced behavioral activity is complex, with increasing evidence that the D1 receptor interacts significantly with N-methyl-D-aspartate (NMDA) receptor pathways to produce an altered behavioral phenotype. To further characterize additional receptor subtypes targeted by the actions of cocaine and cocaethylene, we pretreated flies with MK-801 and dextromethorphan. Both of these drugs are potent, selective noncompetitive NMDA receptor antagonists. Interestingly, MK-801 and dextromethorphan profoundly reduced the behavior-activating properties of cocaine and cocaethylene in Drosophila. Therefore, as in rats, the NMDA (and D1) receptor pathways in this arthropod represent obligatory targets for the behavioral effects of stimulant drugs.

Adrenergic alpha-Agonists↗
PubMed1999

Physiological control of pheromone production in Choristoneura fumiferana and C. rosaceana.

The diel periodicity of calling behavior and pheromone production are synchronous in virgin females of both Choristoneura fumiferana and C. rosaceana (Lepidoptera: Tortricidae). Newly emerged females decapitated prior to scotophase produced no or very little pheromone 24 h later. However, injection of PBAN or Br-SEG homogenates, obtained from donors of the same or the other species, stimulated pheromone production to normal levels. Transection of the ventral nerve cord (VNC) or extirpation of the terminal abdominal ganglion (TAG) did not affect pheromone production in control females. Similarly, injections of PBAN or Br-SEG homogenates into decapitated females reactivated pheromone production to normal levels, whether or not the VNC was intact or the TAG present. Furthermore, octopamine was not effective in stimulating pheromone production in decapitated females. Taken together, these results indicate that the regulation of pheromone production is not neurally mediated in either Choristoneura species. However, there was no evidence that hemolymph collected from pheromone-producing females contained pheromonotropic activity. Similarly, isolated glands incubated with PBAN did not produce pheromone. The presence of the bursa copulatrix was required to produce pheromone in both tortricids as production was not restored in decapitated bursa-less females injected with PBAN or a Br-SEG homogenate. However, an extract of the bursa copulatrix did not elicit pheromonotropic activity in decapitated females or incubated glands of either species. The bursa copulatrix is only involved in pheromone production of some species of tortricids but our results do not support the current explanation for such interspecific differences. We postulate that the relative importance of a bursa factor may be related to the evolution of different desaturation systems used for pheromone biosynthesis in the Tortricidae. Arch.

Animals↗
PubMed2001

Synthesis of lipids in the fat body of Gryllus bimaculatus: age-dependency and regulation by adipokinetic hormone.

The free abdominal fat body of adult female Mediterranean field crickets, Gryllus bimaculatus, synthesizes lipids from [1-(14)C]-acetate in vitro. Up to an age of 12h, the incorporation of acetate into lipids is very low and then rises to a maximum 24h after adult emergence. Thereafter, the incorporation of acetate decreases to moderate levels at day 2 and then slowly decreases until day 30. The adipokinetic hormone of G. bimaculatus (Grb-AKH) significantly inhibits the incorporation of acetate at a concentration of 10(-11) M; maximum inhibition (approximately 95%) is reached at 10(-8) M. The inhibiting effect of Grb-AKH is fast, dose-dependent, and reversible. The periovaric fat body shows a similar pattern of acetate incorporation, although rates of incorporation are lower; the incorporation can be inhibited by Grb-AKH as well. The segmental abdominal fat body and the fat body from the head both incorporate acetate into lipids at low rates that cannot be inhibited significantly by AKH. Prepurified brain extracts significantly inhibit acetate incorporation by free abdominal fat bodies at a concentration of 0.1 brain equivalent. Allatostatins and crustacean cardioactive peptide, which are both present in cricket brains, are not responsible for this inhibiting effect. Octopamine causes a dose-dependent inhibition of acetate incorporation whereas synephrine had no such effect. The inhibiting effect of Grb-AKH on the formation of lipid stores in the fat body and its consequences for reproductive processes are discussed.

Acetates↗
PubMed2001

Apolipophorin-III in the greater wax moth, Galleria mellonella (Lepidoptera: Pyralidae).

The level of apolipophorin-III reached a maximum in the haemolymph of Galleria mellonella at the end of the feeding phase of the seventh larval instar and declined to a plateau value in the pupal and the adult stages. Apolipophorin-III was detected immunologically in fat body tissue, haemocyte lysates, and plasma. In its native state, apolipophorin-III may be associated with another protein with an apparent molecular mass of 77 kDa, possibly apolipophorin-II. Injections of octopamine did not cause lipid loading of high density lipophorin.

Animals↗
PubMed2005

A transporter for phenolamine uptake in the arthropod CNS.

Biogenic monoamines play central roles in the nervous control of physiological processes in both vertebrates and invertebrates, each using a suite of neurotransmitters tailored through evolution. Among the ancillary proteins necessary for the deployment of monoamine transmitters are membrane-bound transporters that enable the reuptake of synaptically released transmitters. Transporters responsible for monoamine uptake include a novel transporter discovered in a pest insect, the cabbage looper Trichoplusia ni, which has high affinity for the phenolamines octopamine and tyramine. Sequence analysis suggests that this transporter has no direct ortholog in the sequenced genomes of model invertebrates. We report here a preliminary investigation into the true extent of the distribution of this type of transporter using RT-PCR with a set of degenerate primers selective for monoamine transporters on cDNAs made from the nervous systems of a range of arthropods. PCR products encoding the N-terminal region of orthologs of this transporter were detected in a variety of insect orders, as well as in a crustacean, but were not found in representatives of either the Diptera or the Hymenoptera. Thus, although this transporter is widely expressed in invertebrates, there are various invertebrates that appear to have evolved alternate ways of recycling phenolamine neurotransmitters released at the nerve synapse.

Animals↗
PubMed1994

Pheromonotropic and pheromonostatic activity in moths.

Pheromone biosynthesis in many species of moths requires a pheromonotropic neurosecretion, the pheromone biosynthesis activating neuropeptide (PBAN), from the brain-subesophageal ganglion-corpora cardiaca complex. Some investigations suggest that PBAN is released into the hemolymph and acts directly on sex pheromone glands (SPG) via a Ca++/calmodulin-dependent adenylate cyclase. Others suggest, however, that PBAN acts via octopamine that is released by nerves from the terminal abdominal ganglion innervating the SPG. These findings suggest that there are controversies on the mode of action of PBAN and other pheromonotropic factors, sometimes even within the same species. Mating in many insects results in temporary or permanent suppression of pheromone production and/or receptivity. Such a suppression may result from physical blockage of the gonopore or deposition of pheromonostatic factor(s) by the male during copulation that result in suppressed pheromone production and/or receptivity in females either directly or by a primer effect. In several species of insects, including moths, a pheromonostatic factor is transferred in the seminal fluid of males. Similar to the controversies associated with the pheromonotropic activity of PBAN, sometimes even within the same species, there appear to be controversies in pheromonostasis in heliothines as well. This paper reviews these conflicting findings and presents some data on pheromonostatic and pheromonotropic activity in Heliothis virescens that support and conflict with current information, raising further questions. Answers to some of the questions are partly available; however, they remain to be answered unequivocally.

Animals↗
PubMed2001

Missing link in firefly bioluminescence revealed: NO regulation of photocyte respiration.

Sexual communication in most species of fireflies is a male-female dialogue of precisely timed flashes of bioluminescent light. The biochemical reactions underlying firefly bioluminescence have been known for 30 years and are now exploited in biomedical assays and other commercial applications. Several aspects of flash regulation are also understood: flash rhythm is controlled by a central pattern generator, and individual flashes are neurally triggered, with octopamine serving as the transmitter. The molecular oxygen needed by the biochemical reactants is delivered by a network of tracheal arborizations extending throughout the light organ (lantern). However, the actual means by which oxygen quickly reaches the reactants packaged within specialized photocytes and the specific event(s) triggered by neural action have not been identified; termination of axons away from the photocytes has exacerbated the latter problem. A recent paper by a consortium of cell and evolutionary biologists, however, reports that nitric oxide (NO), manufactured and released in response to neuronal discharge, is the missing link by which neural action in the firefly lantern yields a sudden flash of light.

Animals↗
PubMed1981

Detection of urinary primary amines through negative chemical ionization mass spectrometry of fluorescamine derivatives.

We report the successful detection of urinary biogenic amines by a procedure which involves isolation of the amines on CG-50 cation exchange resin, derivatization of the amines with fluorescamine while on the resin, followed by direct probe negative chemical ionization mass spectrometry screening of the resin extract. This isolation procedure allowed the detection of tyramine, octopamine, normetanephrine, 3-methoxytyramine and a variety of aliphatic amines. Norepinephrine, dopamine and serotonin were chemically reactive under these conditions and were not detectable at physiological concentrations.

Biogenic Amines↗