Conformational study of octopamine in gas phase and effect of hydrochloride

This work deals with the molecular modeling and vibrational spectra of all the twenty conformers of an important biomolecule octopamine which have been investigated using the DFT/B3LYP level of theory in combination with the 6-31++g(d,p) as a suitable basis set. The experimental FTIR and FTRaman spectra of octopamine neurotransmitter were recorded in the spectral region 400-4000 cm^-1 and 50-4000 cm^-1 respectively and correlated with the calculated spectra of the most stable conformer. The effect of hydrochloride on the important geometrical parameters of most stable conformer of octopamine was also studied. The normal coordinate analysis was performed to scale the theoretical frequencies and to calculate potential energy distributions for precise normal mode assignment. Most of the frequencies were in good agreement with experimental one. However, some have been modified. Natural bond orbital analysis was performed in order to confirm the stability of electronic structure of octopamine molecule. HOMO-LUMO analysis for all the twenty conformers was also performed to give the transition profile and to study the chemical reactivity of octopamine.

3D-printed and CNC milled flow-cells for chemiluminescence detection

Herein we explore modern fabrication techniques for the development of chemiluminescence detection flow-cells with features not attainable using the traditional coiled tubing approach. This includes the first 3D-printed chemiluminescence flow-cells, and a milled flow-cell designed to split the analyte stream into two separate detection zones within the same polymer chip. The flow-cells are compared to conventional detection systems using flow injection analysis (FIA) and high performance liquid chromatography (HPLC), with the fast chemiluminescence reactions of an acidic potassium permanganate reagent with morphine and a series of adrenergic phenolic amines.

Biogenic amines, caffeine and tonic immobility in Tribolium castaneum

Biogenic amines are physiologically neuroactive substances that affect behavioural and physiological traits in invertebrates. In the present study, the effects of dopamine, octopamine, tyramine and serotonin on tonic immobility, or death-feigning, were investigated in Tribolium castaneum. These amines were injected into the abdomens of beetles artificially selected for long or short duration of tonic immobility. In beetles of the long strains, the durations of tonic immobility were shortened by injection of dopamine, octopamine and tyramine, and the effects of these amines were dose-dependent. On the other hand, serotonin injection did not affect the duration of tonic immobility. In the short-strain beetles that rarely feign death, no significant effects of the amines were found on the duration of tonic immobility. Brain expression levels of octopamine, tyramine and serotonin did not differ between long- and short-strain beetles, in contrast to the higher dopamine levels in short strains previously reported. Caffeine decreased the duration of death-feigning in both oral absorption and injection experiments. It is known that caffeine activates dopamine. Therefore, the present results suggest that the duration of tonic immobility is affected by dopamine via the dopamine receptor in T. castaneum.

Determination of Bitter Orange alkaloids in dietary supplements standard reference materials by liquid chromatography with ultraviolet absorbance and fluorescence detection

Four adrenergic amines [synephrine, octopamine, tyramine, and n-methyltyramine] were determined in a variety of Bitter Orange containing dietary supplements. Two extraction techniques were evaluated in detail: Soxhlet extraction and sonication extraction. A liquid chromatographic separation using a reversed-phase C(18) stationary phase and the ion-pairing reagent sodium dodecyl sulfate was developed to separate the Bitter Orange alkaloids. Ultraviolet absorbance detection at 220 nm and fluorescence detection with excitation at 273 nm and emission at 304 nm were used for the alkaloid detection. The method described was used for the assignment of the levels of the predominant alkaloids in three candidate standard reference materials containing Bitter Orange.

Dendritic projections of different types of octopaminergic unpaired median neurons in the locust metathoracic ganglion

Octopaminergic dorsal unpaired median (DUM) neurons of locust thoracic ganglia are important components of motor networks and are divided into various sub-populations. We have examined individually stained metathoracic DUM neurons, their dendritic projection patterns, and their relationship to specific architectural features of the metathoracic ganglion, such as longitudinal tracts, transverse commissures, and well-defined sensory neuropils. The detailed branching patterns of individually characterized DUM neurons of various types were analyzed in vibratome sections in which architectural features were revealed by using antibodies against tubulin and synapsin. Whereas DUM3,4,5 and DUM5 neurons (the group innervating leg and "non-wing-power" muscles) had many ventral and dorsal branches, DUM1 and DUM3,4 neurons (innervating "wing-power" muscles) branched extensively only in dorsal areas. The structure of DUM3 neurons differed markedly from that of the other DUM neurons examined in that they sent branches into dorsal areas and had differently structured side branches that mostly extended laterally. The differences between the branching patterns of these neurons were quantified by using currently available new reconstruction algorithms. These structural differences between the various classes of DUM neurons corresponded to differences in their function and biophysical properties.

A multichannel native fluorescence detection system for capillary electrophoretic analysis of neurotransmitters in single neurons

A laser-induced native fluorescence detection system optimized for analysis of indolamines and catecholamines by capillary electrophoresis is described. A hollow-cathode metal vapor laser emitting at 224 nm is used for fluorescence excitation, and the emitted fluorescence is spectrally distributed by a series of dichroic beam-splitters into three wavelength channels: 250-310 nm, 310-400 nm, and >400 nm. A separate photomultiplier tube is used for detection of the fluorescence in each of the three wavelength ranges. The instrument provides more information than a single-channel system, without the complexity associated with a spectrograph/charge-coupled device-based detector. With this instrument, analytes can be separated and identified not only on the basis of their electrophoretic migration time but also on the basis of their multichannel signature, which consists of the ratios of relative fluorescence intensities detected in each wavelength channel. The 224-nm excitation channel resulted in a detection limit of 40 nmol L-1 for dopamine. The utility of this instrument for single-cell analysis was demonstrated by the detection and identification of the neurotransmitters in serotonergic LPeD1 and dopaminergic RPeD1 neurons, isolated from the central nervous system of the well-established neurobiological model Lymnaea stagnalis. Not only can this system detect neurotransmitters in these individual neurons with S/N>50, but analyte identity is confirmed on the basis of spectral characteristics.

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.

The repertoire of trace amine G-protein-coupled receptors: large expansion in zebrafish

Trace amines, such as tyramine, beta-phenylethylamine, tryptamine, and octopamine, are present in trace levels in nervous systems and bind a specific family of G-protein-coupled receptors (GPCR), but the function or origin of this system is not well understood. We searched the genomes of several eukaryotic species for receptors similar to the mammalian trace amine (TA) receptor subfamily. We identified 18 new receptors in rodents that are orthologous to the previously known TA-receptors. Remarkably, we found 57 receptors (and 40 pseudogenes) of this type in the zebrafish (Danio rerio), while fugu (Takifugu rubripes) had only eight receptors (and seven pseudogenes). We mapped 47 of the zebrafish TA-receptors on chromosomes using radiation hybrid panels and meiotic mapping. The results, together with the degree of conservation and phylogenetic relationships displayed among the zebrafish receptors suggest that the family arose through several different mechanisms involving tetraploidization, block duplications, and local duplication events. Interestingly, these vertebrate TA-receptors do not show a close evolutionary relationship to the invertebrate TA-binding receptors in fruitfly (Drosophila melanogaster), indicating that the ability to bind TA have evolved at least twice in animal evolution. We collected in total over 100 vertebrate TA-receptor sequences, and our phylogenetic analysis shows that several TA-receptors have evolved rapidly with remarkable species variation and that the common ancestor of vertebrate TA-receptors arose before the split of the ray-finned and lobe-finned fishes. The evolutionary history of the TA-receptors is more complex than for most other GPCR families and here we suggest a mechanism by which they may have arisen.

Biogenic amines in the antennal lobes and the initiation and maintenance of foraging behavior in honey bees

Previous findings showed that high levels of octopamine and serotonin in the antennal lobes of adult worker honey bees are associated with foraging behavior, and octopamine treatment induces precocious foraging. To better characterize the relationship between amines and foraging behavior in honey bees, we performed a detailed correlative analysis of amine levels in the antennal lobes as a function of various aspects of foraging behavior. Flight activity was measured under controlled conditions in a large outdoor flight cage. Levels of octopamine in the antennal lobes were found to be elevated immediately subsequent to the onset of foraging, but they did not change as a consequence of preforaging orientation flight activity, diurnal pauses in foraging, or different amounts of foraging experience, suggesting that octopamine helps to trigger and maintain the foraging behavioral state. In contrast, levels of serotonin and dopamine did not show changes that would implicate them as either causal agents of foraging, or as neurochemical systems affected by the act of foraging. Serotonin treatment had no effect on the likelihood of foraging. These results provide further support for the hypothesis that an increase in octopamine levels in the antennal lobes plays a causal role in the initiation and maintenance of the behavioral state of foraging, and thus is involved in the regulation of division of labor in honey bees.

Octopamine modulates spermathecal muscle contractions in Locusta migratoria

Octopamine was identified in the spermathecal tissue of Locusta migratoria using HPLC and immunohistochemical techniques. Octopamine-like immunoreactive unpaired median neurons were identified in the VIIth and VIIIth (terminal) abdominal ganglia and octopamine-like immunoreactive axons were present in the ventral ovipositor nerve (branches from this nerve innervate the spermatheca). Stimulatory actions of octopamine on myogenic and neurogenic contractions were observed. Dose-dependent increases in the frequency of myogenic contractions and the amplitude of neurogenic contractions were elicited by the application of octopamine to the spermathecal muscle. Non-sustained basal tension increases were noted in some preparations, although these were not found to be dose-dependent. SchistoFLRFamide (PDVDHVFLRFamide) inhibited octopamine-induced contractions by a maximum of about 30%. In the presence of 3-isobutyl-1 -methylxanthine, octopamine increased cAMP levels in all regions of the spermathecal. The largest increase in cAMP content was found in the spermathecal sac, followed by the straight duct and coil duct. Phentolamine blocked octopamine-induced increases in cAMP levels and abolished the actions of octopamine on myogenic contractions.

Immunoreactivity against choline acetyltransferase, gamma-aminobutyric acid, histamine, octopamine, and serotonin in the larval chemosensory system of Dosophila melanogaster

We have studied the distribution of choline acetyltransferase (ChAT), gamma-aminobutyric acid (GABA), histamine, octopamine and serotonin in the larval chemosensory system of Drosophila melanogaster. Colocalization at the confocal level with green fluorescent protein (GFP) or Tau-GFP reporters, expressed in selected P[GAL4] enhancer trap lines, was used to identify the cells making up these neurotransmitters. As in the adult fly, larval olfactory afferents project into the (larval) antennal lobe (LAL), where they synapse onto local interneurons and projection neurons, whereas gustatory afferents terminate essentially in the tritocerebral-subesophageal (TR-SOG) region. We demonstrate that the neuropils of the LAL and the TR-SOG are immunoreactive to ChAT and GABA. In addition, serotonin- and octopamine-immunoreactive fibers are present in the LAL. ChAT immunostaining is localized in subsets of olfactory and gustatory afferents and in many of the projection neurons. In contrast, GABA is expressed in most, and perhaps all, of the local interneurons. Serotonin immunoreactivity in the LAL derives from a single neuron that is situated close to the LAL and projects to additional neuropil regions. Taken together, these findings resemble the situation in the adult fly. Hence, given the highly reduced numbers of odorant receptor neurons in the larva, as shown in a previous study (Python and Stocker [2002] J. Comp. Neurol. 445:374-387), the larval system may become an attractive model system for studying the roles of neurotransmitters in olfactory processing.

Determination of adrenergic agonists from extracts and herbal products of Citrus aurantium L. var. amara by LC

The purpose of this study was to set up a HPLC method to separate adrenergic amines (dl-octopamine, dl-synephrine and tyramine) and to determine their content in fruits, extracts and herbal products of Citrus aurantium L. var. amara. A rapid method for the quantitative analysis of these amines is described, based on their separation by RP-HPLC technique with UV detection. The analysis were conducted on a Lichrospher RP-18 column at room temperature, using a mobile phase consisting of 0.02 M citric acid-0.02 M NaH2PO4 (7:3 v/v) and adjusted to a final pH of 3. The detection was at 220 nm. Since some of these amines are chiral compounds and their enantiomers showed different pharmacological activity, the direct separation of synephrine enantiomers was carried out with HPLC on a beta-cyclodextrin stationary phase. The mobile phase consisted of methanol-NaH2PO4 25 mM pH 3.5 (20:80 v/v) and tetrabutylammonium hydrogen sulfate 10 mM in ratio of 30:70 v/v in isocratic condition and the detection was at 220 nm. The two proposed methods were applied to the analysis of fruits, extracts and herbal products of C. aurantium L. var. amara. Taking into account that some authors have reported that l-synephrine may be converted into its d-form by high temperature, this optical isomerization was monitored by the same HPLC method used for the separation of enantiomers.

Serotonergic and octopaminergic systems in the squat lobster Munida quadrispina (Anomura, Galatheidae)

Immunocytochemical mapping of serotonergic and octopaminergic neurons in the central nervous system of the squat lobster Munida quadrispina reveal approximately 120 serotonin-immunoreactive cell bodies (distributed throughout the neuromeres except in abdominal ganglion 5) and 48 octopamine-immunoreactive cell bodies (in brain and thoracic neuromeres but none in the circumesophageal or abdominal ganglia). Immunopositive neuropils for both amines are distributed in multiple areas in each neuromere and overlap extensively. Serotonergic and octopaminergic neurons have extensive bilateral projections in abdominal ganglia, whereas the majority of projections in thoracic and subesophageal ganglia are unilateral (contralateral to soma). This difference correlates with typical differences between abdominal and thoracic motor system coordination. Processes of immunoreactive cells for both amines form extensive, peripheral, neurosecretory-like structures. Serotonin seems to be released peripherally in more segments, and from more nerves per segment, than octopamine. M. quadrispina has fewer serotonergic and octopaminergic immunoreactive cells, in particular, fewer segmentally repeated cells, than other species studied to date. Nevertheless, the general organization of the aminergic systems is similar, and several aminergic cells have locations and morphologies that strongly suggest homology with identified aminergic cells in other crustaceans. Among these are segmentally repeated neurons that, in M. quadrispina, form serotonin-immunopositive tubular structures in the thoracic hemiganglia innervating pereiopods 1-3 that are unlike anything reported previously for any species. Comparisons of immunocytochemical maps within one species and between species exhibiting different behaviors provide insights into possible sites of action, functional differences between, and evolution of biogenic aminergic systems.

Colocalisation of taurine- with transmitter-immunoreactivities in the nervous system of the migratory locust

The expression of taurine immunoreactivity (TAU-IR) by neurones immunoreactive for octopamine (OA-IR), gamma-aminobutyric acid (GABA-IR), and the C-terminal peptide sequence arginine-phenylalanine (RFamide-IR) was investigated in the migratory locust (Locusta migratoria). TAU-IR is colocalised with OA-IR in the dorsal unpaired median neurones, which are efferent neuroparacrine cells. TAU-IR is not, however, expressed by OA-IR interneurones in the thoracic ganglia and brain. The only other TAU-IR somata found with peripheral axons are the medial neurosecretory cells in abdominal ganglia that project to the neurohaemal organs. These cells exhibit RFamide-IR. The majority of TAU-IR somata in the thoracic abdominal nervous system exhibit GABA-IR. These cells correspond to populations of identified local and intersegmentally projecting inhibitory interneurones. TAU-IR is not, however, exhibited by the well-known GABAergic common inhibitor neurones, which have peripherally projecting axons. This differential distribution of TAU-IR in basically two, functionally different, neuronal subsets (efferent neurosecretory and neuroparacrine cells, inhibitory interneurones) conforms with the concept of taurine acing as a depressive agent to limit excitation during stressful conditions.

Distribution and functional anatomy of amine-containing neurons in decapod crustaceans

One of the lessons learned from studying the nervous systems of phylogenetically distant species is that many features are conserved. Indeed, aminergic neurons in invertebrate and vertebrate systems share a multitude of common characteristics. In this review, the varied roles of serotonin, octopamine, dopamine, and histamine in decapod crustaceans are considered, and the distributions of the amine-containing cells are described. The anatomy of these systems reinforces the idea that amine neurons are involved in widespread modulation and coordination within the nervous system. Many aminergic neurons have long projections, linking multiple regions with a common input, and therefore are anatomically perfected as "gain setters." The developmental patterns of appearance of each amine in the crustacean nervous system are described and compared. The developmental picture suggests that transmitter acquisition is distinctive for each amine, and that the pace of acquisition may be co-regulated with target maturation. The distinctive roles that transmitters play during specific developmental periods may, ultimately, provide important clues to their functional contributions in the mature organism.

Cytoarchitecture of histamine-, dopamine-, serotonin- and octopamine-containing neurons in the cricket ventral nerve cord

The present article provides a comparative neuroanatomical description of the cellular localization of the biogenic amines histamine, dopamine, serotonin and octopamine in the ventral nerve cord of an insect, namely the cricket, Gryllus bimaculatus. Generally, different immunocytochemical staining techniques reveal a small number of segmentally distributed immunoreactive (-IR) amine-containing neurons allowing single cell reconstruction of prominent elements. Aminergic neurons share common morphological features in that they innervate large portions of neurophil and often connect different neuromeres by intersegmental 'wide-field' projections of varicose appearance. In many cases aminergic terminals are also found on the surface of peripheral nerves suggesting additional neurohemal release sites. Despite such morphological similarities histological analysis demonstrates for any given amine functionally distinct neuron types with specific innervation patterns establishing discrete pathways. Histamine-IR interneurons are characterized by both ascending and descending projections forming central and peripheral terminals. The descending branches from dopamine-IR cells mainly converge within the terminal ganglion, whereas serotonin-IR interneurons with ascending projections often terminate within the brain. Serotonin is also present in sensory and motor neurons. In contrast to other aminergic neurons, most octopamine-IR cells represent unpaired neurons projecting through motor nerves of the soma-containing neuromere. Octopamine-IR cells with intersegmental branches are only rarely found. Based on these findings, a colocalization of different amines within the same neuron seems to be unlikely to occur in the cricket ventral nerve cord. With respect to the neuroanatomical description of amine-containing neurons known physiological effects of biogenic amines and their possible neuromodulatory functions in insects are discussed.

Octopamine-containing neurons in the alimentary tract of the earthworm (Eisenia fetida)

Octopamine-containing nerve cells have been demonstrated in the enteric plexus of the earthworm (Eisenia fetida), applying immunocytochemistry and HPLC assay. A few octopamine-immunoreactive neurons occurred in the fore- and hindgut, whereas their number in the midgut was considerably greater. Octopamine levels detected by HPLC correlated with the distribution of octopamine-containing nerve cells. A regulatory role for these intrinsic octopaminergic neurons is suggested in the enteric plexus in the earthworm alimentary tract. This is the first report on the occurrence of octopamine-containing nerve cells in the peripheral nervous system of an invertebrate.

Mechanism-based inactivation of dopamine beta-monooxygenase in adrenal chromaffin cells

Dopamine beta-monoxygenase (DBM, E.C. 1.14.17.1) is an attractive target point for possible modulation of adrenergic activity, and a variety of DBM-targeted pseudosubstrates and inhibitors have been developed in this laboratory and other laboratories. We now demonstrate the efficacy of a DBM-targeted mechanism-based inactivator, as well as enzymatic processing of two alternate DBM substrates, within functional adrenal chromaffin cells. When cultured adrenal medullary chromaffin cells were incubated with the mechanism-based inactivator 1-(4'-hydroxyphenyl)-1-(aminomethyl)-ethene (HOPAME), vesicular DBM activity was markedly decreased. Similarly, the alternate substrates 4'-hydroxyphenyl-2-aminoethyl sulfide and 4'-hydroxyphenyl-2-aminopropyl selenide each undergo uptake and DBM-catalyzed oxygenation within these cells. The simultaneous action of both the mechanism-based inactivator and an alternate substrate within functional chromaffin cells was also demonstrated. These results provide support for a direct mechanistic link between the enzymological properties of DBM-targeted adrenergic agents and their in-vivo pharmacological activities.

Developmental expression of the octopamine phenotype in lobsters, Homarus americanus

We have used immunocytochemical methods to examine the sequence of appearance of octopamine-immunoreactive neurons during development, and to try to correlate that appearance with the emergence of behavioral or physiological capabilities. The first octopamine neurons express their transmitter phenotype at approximately 43% of embryonic development. The last cells show immunostaining at the 3rd larval stage. In the wild, therefore, immunoreactivity in cells appears over a 9-12 month period. In contrast, serotonin-immunoreactive neurons stain early in embryonic development and the last serotonin-immunoreactive cells appear at about the same time the first octopamine-immunoreactive neurons show staining. The pattern of appearance of octopamine-immunoreactive cells is cell type-specific. A pair of brain cells and the descending interneurons stain first. Additional brain cell staining is seen throughout embryonic development. The ascending interneurons appear next, and a general anterior-posterior gradient typifies their emergence over a relatively short portion of embryonic life (E 48-62%). The neurosecretory cell staining appears last, is segment-specific, begins at about 62% development, and continues to the 3rd larval stage. The emergence of immunostaining for amine neurotransmitters within groups of identified neurons at precise times in development may specify possible functional units. With at least one group of cells, this possibility seems plausible: the three pairs of claw octopamine neurosecretory cells show immunostaining as a unit.

Octopamine-like immunoreactivity in the brain and subesophageal ganglion of the honeybee

The organization of putative octopaminergic pathways in the brain and subesophageal ganglion of the honeybee was investigated with a well-defined polyclonal antiserum against octopamine. Five prominent groups of just over 100 immunoreactive (IR) somata were found in the cerebral ganglion: Neurosecretory cells in the pars intercerebralis innervating the corpora cardiaca via NCC I, one cluster mediodorsal to the antennal lobe, one scattered on both sides of the midline of the protocerebrum, one between the lateral protocerebral lobes and the dorsal lobes, and a single soma on either side of the central body. With the exception of the pedunculi and beta-lobes of the mushroom bodies, varicose immunoreactive fibers penetrate all parts of the cerebral ganglion. Strong labelling was found in the central complex and the protocerebral bridge. Fine networks of labelled processes invade the antennal lobes, the calyces and a small part of the alpha-lobes of the mushroom bodies, the protocerebrum, and all three optic ganglia. In the subesophageal ganglion, one labelled cell body was found in the lateral soma layer of the mandibular segment. Each of the three neuromeres contains a group of six to ten somata in the ventral median parts. Most of the ventral median cells send their neurites dorsally through the midline tracts, whereas the neurites of a few cells follow the ventral cell body neurite tracts. Octopamine-IR was demonstrated in all neuropils that contain pathways for proboscis extension learning in honeybees. Because octopaminergic mechanisms seem to be involved in the behavioral plasticity of the proboscis extension reflex, our study provides anatomical data on the neurochemical organization of an appetitive learning paradigm.

Colocalization of octopamine and FMRFamide related peptide in identified heart projecting (DUM) neurones in the locust revealed by immunocytochemistry

Immunocytochemical techniques are employed to reveal colocalization of octopamine with FMRFamide related peptide in the locust ventral nervous system. In each unfused pregenital abdominal ganglia (A4-A6) there are 3 octopamine-like immunoreactive neurones. By combining intracellular Lucifer yellow staining with subsequent immunocytochemistry these are individually identified as the efferent dorsal unpaired median (DUM) neurones DUM-1 and DUM-2, which innervate abdominal tergal and respectively sternal skeletal muscles, and DUM heart-1, an FMRFamide-like immunoreactive neurone which projects to the heart and associated alary muscles. Colocalization of octopamine- and FMRFamide-like immunoreactivity in DUM heart-1 is verified by alternate staining of consecutive sections. With respect to locust ventral ganglia, this investigation shows that colocalization of octopamine with an FMRFamide related peptide is restricted to a single DUM cell occurring in each abdominal ganglion 2-7, which most likely corresponds to segmental homologues of DUM heart-1.

The determination of biogenic amines in four strains of the fruit fly Drosophila melanogaster

A range of biogenic amines were measured in the heads from four strains of Drosophila melanogaster. Quantitation was carried out using gas chromatography-negative ion chemical ionization mass spectrometry (GC-NICIMS) with stable isotope dilution. The principal amines detected in the heads were dopamine, noradrenaline and 5 HT with small amounts of p- and m-tyramine; p-octopamine could not be detected in samples of 25 heads with a limit of detection of 10 pg per sample. In addition to conventional neurotransmitters or putative neurotransmitters the amines 5- and 6-hydroxydopamine were detected in the heads in substantial amounts.

Identification and quantification of gamma-glutamyl conjugates of biogenic amines in the nervous system of the snail, Helix aspersa, by gas chromatography-negative-ion chemical ionisation mass spectrometry

The gamma-glutamyl conjugates of p-octopamine and dopamine were identified unambiguously for the first time and quantified in a single cerebral ganglion or pleural plus pedal ganglia of the snail, Helix aspersa, by gas chromatography-negative-ion chemical ionisation mass spectrometry. A new method was used for synthesis of gamma-glutamylamine standards. The concentration of gamma-glutamyltyramine was found to be low in the tissues, therefore it was used as an internal standard. The gamma-glutamylamines were extracted with water and derivatised with pentafluoropropionic anhydride and trifluoroethanol. Under negative-ion chemical ionisation conditions, the trifluoroethyl and pentafluoropropionyl derivatives produced significant ions which were sufficiently abundant to be suitable for selective ion monitoring. The method had a limit of detection of ca. 80 pg of gamma-glutamyl conjugate per tissue and calibration curves were linear over the range examined.

Octopamine immunoreactive neurons in the fused central nervous system of spiders

Using antisera directed against octopamine (OA), we identified and mapped octopamine-immunoreactive (OA-ir) neurons and their projections in the fused, central ganglion complex of wandering spiders, Cupiennius salei. Labeled cell bodies are concentrated in the subesophageal ganglion complex (SEG) where they are arranged serially in ventral, midline clusters. OA-ir processes from these cells project dorsally. Some neurites end close to segmental septa; others merge into longitudinal tracts connecting the neuromeres. Labeled collaterals leaving these tracts project into peripheral neuropil. In the brain, OA-ir somata were found only in the two cheliceral hemiganglia, where a cluster of 4-5 relatively large cells (soma diameter 25 microns) lies next to a group of small somata (diameter < 10 microns). Neurites originating from the large somata descend into the SEG and merge into longitudinal tracts. The central body of the brain contains profuse ascending projections. Except for fine varicosities that are confined to the roots of nerves, we found no OA-ir fibers leaving the central nervous system (CNS). Within the CNS, however, OA-ir varicosities are concentrated in neuropil and near hemolymph spaces. This distribution suggests that OA acts as a neurotransmitter and/or local neuromodulator at central synapses, while it is also released into the hemolymph and presumably acts hormonally at peripheral sites. Using high-pressure liquid chromatography measurements, the hemolymph was in fact found to contain 12-40 nM of free octopamine.

Mapping of octopamine-immunoreactive neurons in the central nervous system of the lobster

It has been suggested that serotonin and octopamine serve important roles in behavioral regulation in lobsters. In this paper the locations of octopamine-immunoreactive neurons were mapped in wholemount preparations of the ventral nerve cord of 4th stage lobster (Homarus americanus) larvae. Approximately 86 neurons were found, distributed as follows: brain, 12; circumesophageal ganglia, 2; subesophageal ganglion, 38; thoracic ganglia, 6 each; and 4th and 5th abdominal ganglia, 2 each. All the octopamine-immunoreactive neurons are paired and located along the midline. Of the 86 neurons, 28 were identified as neurosecretory, and 26 as intersegmental ascending thoracic, ascending abdominal, or descending interneurons. The neurosecretory system is arranged segmentally and located entirely within the thoracic and subesophageal neuromeres with extensive terminal fields of endings along 2nd thoracic and subesophageal nerve roots. This set of neurons shares the features of central and peripheral endings with 2 pairs of large serotonin-containing neurosecretory neurons found in the fifth thoracic and first abdominal ganglia. The intersegmental neurons include: (1) two cells in the brain and 2 pairs of cells in the 3rd and 4th neuromeres of the subesophageal ganglion, which project to the 6th abdominal ganglion; (2) a segmentally organized group of ascending interneurons found in the subesophageal and in all thoracic ganglia; and (3) pairs of ascending interneurons found in the 4th and 5th ganglia in the abdominal nerve cord. By means of a biochemical assay, the cell bodies of octopamine-immunoreactive neurosecretory cells in the thoracic segment of the nerve cord were found to contain 40-100 fmol of octopamine, while control neurons had none.

A new specific antibody reveals octopamine-like immunoreactivity in cockroach ventral nerve cord

An antiserum was raised in rabbits immunized with octopamine conjugated to thyroglobulin. The specificity of this antiserum for octopamine is shown by dot blot immunoassay analysis. The antiserum does not crossreact with dopamine, noradrenaline, and serotonin, but slight crossreactivity with the amine tyramine at high concentrations was observed. The tyramine crossreactivity could be eliminated by preabsorption with a tyramine-glutaraldehyde-BSA conjugate. Using this antiserum, we describe the topographical distribution of octopamine-immunoreactive (ir) neuronal elements in wholemounts and paraffin sections of the ventral nerve cord of the American cockroach. The pattern of octopamine immunostaining is completely different from that obtained with an antidopamine serum, and can be blocked by preabsorbing the antioctopamine serum with BSA-conjugated octopamine. Cell bodies and dendritic processes of putatively octopaminergic dorsal (DUM) and ventral (VUM) unpaired median neurons were clearly octopamine-ir in all ganglia examined. The numbers of stained DUM somata in the mesothoracic, metathoracic, and terminal ganglion of females correspond to those of peripherally projecting DUM cells revealed previously by retrograde tracing (Gregory, Philos Trans R Soc Lond [Biol] 306:191, 1984; Tanaka and Washio, Comp Biochem Physiol 91A:37, 1988; Stoya et al., Zool Jb Physiol 93:75, 1989). In addition, various, previously unknown, paired cells with octopamine-like immunoreactivity were found in all ventral ganglia except abdominal ganglia 3-6. Some of these probably project intersegmentally.

Octopamine-immunoreactive neurons in the central nervous system of the cricket, Gryllus bimaculatus

The distribution of octopamine-immunoreactive neurons is described using whole-mount preparations of all central ganglia of the cricket, Gryllus bimaculatus. Up to 160 octopamine-immunoreactive somata were mapped per animal. Medial unpaired octopamine-immunoreactive neurons occur in all but the cerebral ganglia and show segment-specific differences in number. The position and form of these cells are in accordance with well-known, segmentally-organized clusters of large dorsal and ventral unpaired medial neurons demonstrated by other techniques. In addition, bilaterally arranged groups of immunoreactive somata have been labelled in the cerebral, suboesophageal and terminal ganglia. A detailed histological description of octopamine-immunoreactive elements in the prothoracic ganglion is given. Octopamine-immunoreactive somata and axons correspond to the different dorsal unpaired medial cell types identified by intracellular single-cell staining. In the prothoracic ganglion, all efferent neurons whose primary neurites are found in the fibre bundle of dorsal unpaired cells are immunoreactive. Intersegmental octopamine-immunoreactive neurons are also present. Collaterals originating from dorsal intersegmental fibres terminate in different neuropils and fibre tracts. Fine varicose fibres have been located in several fibre tracts, motor and sensory neuropils. Peripheral varicose octopamine-immunoreactive fibres found on several nerves are discussed in terms of possible neurohemal releasing sites for octopamine.

Immunocytochemical localization of octopamine in the central nervous system of Limulus polyphemus: a light and electron microscopic study

We have determined the distribution and localization of the monoamine octopamine in the prosomal central nervous system of the horseshoe crab, Limulus polyphemus, by light and electron microscopic immunocytochemistry. Sixteen discrete clusters of octopamine-like immunoreactive neurons are situated bilaterally in the tritocerebrum and circumesophageal ring of fused thoracic ganglia. Two pairs of anterior clusters are located laterally in the cheliceral and first pedal ganglia; the remaining six pairs of clusters are located ventromedially in the second through fifth pedal ganglia, chilarial ganglia, and opercular ganglia. The immunoreactive somata range from about 40 to 100 microns in diameter and occur in clusters of 12-24 cells. There is extensive distribution of octopamine-immunoreactive nerve fibers in Limulus; dense fiber tracts course anteroposteriorly through the central nervous system, and most neuropil regions are innervated by immunoreactive processes and terminals. This wide distribution of octopamine-like immunoreactivity provides an anatomical basis for the several effects of octopamine in Limulus. We determined the subcellular localization of octopamine by postembedding immunoelectron microscopy. The immunogold-labelled terminals are morphologically unique; they contain large, distinctively shaped dense-core granules, typically cylindrical with a prominent indentation in one end. These large granules are 100-150 nm in diameter and range from 150-400 nm in length. The dense labelling of these unusual granules with immunogold particles indicates that octopamine is sequestered in or associated with the granules.

High-performance liquid chromatography of biogenic amines in the corpus cardiacum of the American cockroach, Periplaneta americana

The simultaneous determination of biogenic amines in the corpus cardiacum of the American cockroach, Periplaneta americana, was carried out using high-performance liquid chromatography with a Neurochem neurochemical analyser. Vanillic acid, dopamine, octopamine and tyramine were detected. Tyrosine and tryptophan were also detected at high levels. Octopamine levels in the corpus cardiacum were increased on injection of an acetone solution. The biological function of the biogenic amines detected is discussed.

Biogenic amines: their occurrence, biosynthesis and metabolism in the locust, Schistocerca gregaria, by gas chromatography-negative-ion chemical ionisation mass spectrometry

Extraction-derivatisation techniques have been developed for the unambiguous identification of biogenic amines, and their putative amino acid precursors and metabolites (both major and minor), in single ventral thoracic nerve cords of the locust. Schistocerca gregaria, by the use of gas chromatography-negative-ion chemical ionisation mass spectrometry with selected ion monitoring. In addition the configuration of that enantiomer of p-octopamine present in the thoracid nervous system of the locust was established as R using the chiral derivatisation reagent, (-)-heptafluorobutyrylphenylalanyl chloride.

Alterations of GABA-A and dopamine D-2 brain receptors in dogs with portal-systemic encephalopathy

The binding characteristics of gamma-aminobutyric acid-A (GABA-A) receptors and the kinetic characteristics of the target enzyme of GABA synthesis in nerve terminals, glutamic acid decarboxylase (GAD), were studied in a dog model of portal-systemic encephalopathy obtained by porta-caval shunt performed in dimethylnitrosamine pretreated animals. Furthermore the properties of dopamine receptors and the levels of catecholamines of encephalopathic dogs were investigated. The mild stage of encephalopathy was characterized by an up-regulation of the inhibitory GABA-A receptors probably related to a decrese of GABA in nerve terminals since GAD was decreased and by a slight decrease of catecholamines and by an increased synthesis of octopamine associated with a decreased affinity of dopamine receptors. In the severe stage there was a selection of high affinity GABA-A receptors with an increased number of benzodiazepine recognition sites which were supersensitive to GABA stimulation, a decreased number of Dopamine D-2 receptors and a marked reduction of catecholamines. These data seem to suggest that the neurological disturbances of experimental portal-systemic encephalopathy might be the result of an imbalance between inhibitory and excitatory systems leading to a prevalence of the first one.

Identification and quantitation of N-acetyl metabolites of biogenic amines in the thoracic nervous system of the locust, Schistocerca gregaria, by gas chromatography-negative-ion chemical ionisation mass spectrometry

The N-acetylated metabolites of p-tyramine, p-octopamine and dopamine were identified unambiguously and quantitatively determined in a single ventral thoracic nerve cord of the locust, Schistocerca gregaria, by gas chromatography-negative-ion chemical ionisation mass spectrometry (GC-NICIMS). Deuterium-labelled analogues of each compound were added to a single ventral thoracic nerve cord in acetonitrile: the tissue was homogenised and the suspension centrifuged. The solvent was removed from the supernatant and the resultant residue was derivatised with trifluoroacetic anhydride. Under negative-ion chemical ionisation conditions, the trifluoroacetyl derivatives produced ions which were sufficiently abundant to be suitable for selected-ion monitoring. This method is highly specific and gave a limit of detection below the picogram levels. N-Acetyl-5-hydroxytryptamine was determined using a previously published GC-NICIMS technique [S.P. Markey, R.W. Colburn and J.N. Johannessen, Biomed. Mass Spectrom., 7 (1981) 301]. The concentrations of N-acetyltyramine, N-acetyloctopamine, N-acetyldopamine and N-acetyl-5-hydroxytryptamine in locust thoracic nerve cords were, respectively, 1.86 +/- 0.71, 1.13 +/- 0.34, 6.77 +/- 8.48 and 0.07 +/- 0.02 ng per tissue.

The effects of octopamine on juvenile hormone biosynthesis, electrophysiology, and cAMP content of the corpora allata of the cockroach Diploptera punctata

Juvenile hormone production by the corpora allata of the adult female cockroach, Diploptera punctata, can be modulated by treatment with the biogenic amine, octopamine. Endogenous octopamine has been identified within the CA, using HPLC and electrochemical detection. Treatment with octopamine results in a sinusoidal, dose-dependent inhibition of JH biosynthesis by CA from day 2 virgin females, with maximal inhibition occurring at 10(-10) M and 10(-4 M. In day 4 and day 8 mated female corpora allata octopamine inhibited JH biosynthesis at 5 x 10(-5) M. Although the elevation of either cAMP or cGMP within the CA is known to be associated with an inhibition of JH biosynthesis, treatment with high concentrations of octopamine results in an increase in the level of cAMP but not cGMP. This effect is both dose- and time-dependent. Octopamine treatment also initiates changes in the passive membrane responses of the CA. Superfusion of CA with octopamine results in a pronounced hyperpolarization of CA cells and an increase in the electrotonic potential (indicative of the degree of electrical coupling between CA cells). This effect could be blocked by the octopamine receptor blocker phentolamine. Treatment with octopamine or phentolamine also blocked the hyperpolarization of CA cells normally associated with electrical stimulation of the axon tracts innervating the CA. We hypothesize that octopamine may be a natural neuromodulator of JH production by CA, regulating ion channels in CA cells themselves as well as release of the inhibitory neuropeptide, allatostatin, from the terminals within the CA.

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.

Determination of dopamine, norepinephrine, and related trace amines by prechromatographic derivatization with naphthalene-2,3-dicarboxaldehyde

Dopamine, norepinephrine, octopamine, tyramine, and 3,4-dihydroxybenzylamine react readily with naphthalene-2,3-dicarboxaldehyde in the presence of cyanide ion under mild conditions to give highly fluorescent cyanobenz[f]isoindole (CBI) products. The CBI products exhibit good solution chemical stability. The high-fluorescence quantum efficiency of the CBI fluorophore and the ability to excite these adducts in the visible region (420-450 nm) enhance the sensitivity and selectivity of this derivatization detection technique. The CBI products of catecholamines and "trace" amines are readily separated by reverse-phase HPLC giving detection limits in the 20 to 60 fmol range (S/N = 3). A prechromatographic derivatization HPLC assay for the trace analysis of dopamine and norepinephrine in urine is described.

Immunocytochemical demonstration of octopamine-immunoreactive cells in the nervous system of Locusta migratoria and Schistocerca gregaria

The distribution of octopamine in the metathoracic ganglion, brain and corpus cardiacum of Locusta migratoria and Schistocerca gregaria was investigated by means of immunocytochemistry with an antiserum against octopamine. The dorsal unpaired median (DUM) cells of the metathoracic ganglion were found to be strongly octopamine-immunoreactive. In the rostroventral part of the protocerebrum a group of seven immunopositive cells was demonstrated. Stained nerve fibres of these cells run into three directions: circumoesophageal connectives, midbrain, and optic lobes. As far as the protocerebrum is concerned, immunoreactive fibres were found in the central body, the protocerebral bridge, and in other neuropile areas. In the optic lobe a dense plexus of immunopositive fibres was found in the lobula and in the medulla. In the brain one other immunopositive cell was demonstrated, situated at the lateral border of the tritocerebrum. Octopamine could not be shown to occur either in the globuli cells of the mushroom bodies or in the dorsolateral part of the protocerebrum, where the perikarya of the secretomotor neurones are located that innervate the glandular cells of the corpus cardiacum. In the nervi corporis cardiaci II, which contain the axons of the neurones that extend into the glandular part of the corpus cardiacum, and in the corpus cardiacum proper no specific octopamine immunoreactivity could be found.

Psychophysiological profiles of the Roman strains of rats

Male rats of the Roman High and Roman Low Avoidance strains were submitted to four principal behavioral tests: food-motivated acquisition of bar-pressing in Skinner box, delayed reinforced alternation, locomotor activity in a "multibox apparatus," conditioned suppression, and two biological measures: blood pressure and brain octopamine level. Performances of RLA and RHA rats were significantly different in each behavioral test. Blood pressure was higher in RHA, but the difference only approached the 0.05 threshold. As previously reported, brain octopamine levels of RHA rats were significantly higher than those of RLA. A multivariate treatment (analysis of correspondences) was applied to the data of 10 behavioral tests. The main factor extracted by this treatment clearly separated the two strains. Among the variables which best differentiate RHA and RLA rats, several do not involve stress (working memory, acquisition of bar-pressing, and locomotor activity).

m-Octopamine: normal occurrence with p-octopamine in mammalian sympathetic nerves

The development of a radiochemical enzyme assay for p-octopamine in 1969 led to its identification in a large number of invertebrate nerve systems and in mammalian sympathetic nerves. The original method by which p-octopamine was measured has now been found to be nonspecific; however, modifications of this procedure can determine both m- and p-octopamine. We recently developed a new specific method for the unequivocal identification and quantitative determination in tissue of the six octopamine and synephrine isomers. With this method--negative chemical ionization gas chromatography-mass spectrometry--the more physiologically active m-octopamine has been found in association with p-octopamine in 10 organs of the rat. m-Octopamine is present in concentrations equal to those of p-octopamine in heart, spleen, and liver and in concentrations from 30 to 60% of p-octopamine in adrenals, vas deferens, brain, kidney, large intestine, bladder, and lungs. In vivo inhibition of monoamine oxidase markedly increased the concentrations of both m- and p-octopamine in all organs examined. Both amines were virtually absent from all organs except the adrenals following chemical sympathectomy with 6-hydroxydopamine, thereby establishing that m- and p-octopamine are localized within sympathetic nerve endings.

Relationship between phenolamines and catecholamines during rat brain embryonic development in vivo and in vitro

p-Octopamine and phenylethanolamine are present in the embryonic rat brain earlier than catecholamines. These phenolamines are localized mainly in the hypothalamus, where the level of p-octopamine is very high. The parallel developmental study of the activities of dopamine beta-hydroxylase, 3,4-dihydroxyphenylalanine decarboxylase, tyrosine hydroxylase, and monoamine oxidase shows that phenolamines are present in significant amounts in the hypothalamus until tyrosine hydroxylase and monoamine oxidase become catalytically active. The culture of embryonic hypothalamus at different ages shows that no tyrosine hydroxylase and monoamine oxidase activities can be detected if the tissue is cultured before 15 days. This clearly indicates that all the enzymes related to catecholamine biosynthesis are not triggered at the same time during the development of the rat brain. These results are discussed on the basis of the physiological importance of phenolamines in mammals and of the use of the developing rat brain as a model for the study of the onset of the catecholaminergic system and the decline of the octopamine.

Prenatal ontogenesis of p-, m-octopamine and phenylethanolamine in relation to catecholamines and their metabolizing enzymes in the developing rat brain and heart

Non-catecholamines such as phenylethanolamine and p-octopamine are present in many invertebrate nervous systems, sometimes in large amounts. These amines are normally present in the rat brain at much lower levels, p- and m-octopamine are present at trace levels in the mammalian brain. The prenatal development of these amines was studied in comparison with those of noradrenaline and dopamine. The activities of tyrosine hydroxylase, dopa decarboxylase, dopamine beta-hydroxylase and monoamine oxidase were determined in parallel. Phenylethanolamine and p-octopamine are more abundant in the brain between 13 and 17 fetal days than dopamine and noradrenaline but decrease after 17 days whereas the levels of m-octopamine and the two catecholamines increase afterwards. Dopa decarboxylase, dopamine beta-hydroxylase and tyrosine hydroxylase are detected early in fetal life (13, 15 and 14.5 days respectively) but monoamine oxidase activity was not found before 18 days.

Biogenic amines and DOPA in the central nervous system of decapod crustaceans

The biogenic amines serotonin (5-HT), dopamine (DA), noradrenaline (NA), octopamine (OA) and the amino acid dihydroxyphenylalanine (DOPA) were identified and measured in the brain and the eyestalks of five decapod crustacean species using high pressure liquid chromatography (HPLC) with electrochemical detection. The amounts fall within 0.01-1.1 micrograms/g or 0.17-60 pmoles, and OA is the dominating amine in most species. THe DOPA levels in many of the species varied considerably between different measurements. It is concluded that the biogenic amines and DOPA are ubiquitous in the central nervous system of decapod crustaceans and the presence of NA and DOPA increases the number of presumed neurotransmitter/modulator candidates in the crustacean nervous system.

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.

Biogenic amines in the brain of the honeybee, Apis mellifera

Fluorescence histochemistry with glyoxylic acid has been used in close conjunction with detailed anatomical studies (Mobbs 1982) to investigate the distribution of fluorogenic amines in the brain of the honeybee, Apis mellifera. In addition, the concentration and distribution of biogenic amines in the brain of the bee have been determined using highly sensitive radioenzymatic techniques and high performance liquid chromatography. The cerebral ganglia of the bee contain similar amounts of dopamine and serotonin, more dopamine than octopamine, and very low levels of noradrenaline. Slow fading green fluorescence, typical of catecholamines, was located throughout the cerebral ganglia, and was particularly intense in the central body and mushroom body neuropils. Results indicate that the fluorescence in the mushroom body neuropils is largely extrinsic in origin. Both dopamine and serotonin were detected in the calyces and alpha-lobe of the mushroom bodies, and in the antennal lobe. In the optic lobe, however, serotonin was found, but only low levels of dopamine were detected. Slow fading green fluorescence was replaced in the optic lobes by fluorescence which faded rapidly in the excitation light. The non-fluorogenic amine octopamine was found in the mushroom bodies and in the neuropils of the optic lobes, with the largest amounts of octopamine in the optic lobes associated with the neuropil of the medulla. The possibility that intrinsic neurones of the mushroom body neuropil are octopaminergic is discussed.

Dopamine-beta-hydroxylase activity of the cat carotid body under different arterial O2 and CO2 conditions

To determine the importance of dopamine and noradrenaline as neurotransmitters during chemoreception in the cat carotid body we investigated the contents of both compounds as well as the activity of dopamine-beta-hydroxylase (DBH) under different arterial PO2 and PCO2 conditions. The superior cervical ganglion was used as a control organ. In the carotid body and the ganglion an inverse relationship exists between the catecholamine content and the DBH activity. The carotid body has a high catecholamine content with a low DBH activity whereas the superior cervical ganglion has a low catecholamine content and high DBH activity. Hypercapnia did not produce any significant change in the catecholamine content or in the DBH content of the carotid body. However, in comparison with hyperoxia, hypoxia produced a significant change (p less than 0.05) in the noradrenaline content without changing the DBH activity. The dopamine content under these conditions did not change significantly. The results may indicate that the high catecholamine content of the carotid body is the result of a high retention and/or low rate of degradation rather than of a high rate of synthesis.

Autoradiographic localization of newly synthesized octopamine to retinal efferents in the Limulus visual system

The biogenic amine octopamine is synthesized from both tyrosine and tyramine in the lateral, median, and ventral eyes of Limulus. The autoradiographic studies presented here were designed to locate the sites of octopamine synthesis in the ventral and lateral eyes. We found that efferent fibers, which project to ventral and lateral eyes from the central nervous system, became intensely and selectively labeled during in vitro incubations with 3H-tyramine. In the ventral eye, more than 95% of the efferent fibers were labeled. Results of biochemical analyses suggested that most of the radioactive substance within these efferent fibers was newly synthesized octopamine. The selective labeling of efferent fibers during incubation with 3H-tyramine was used as an anatomical tool to study the number and distribution of efferent fibers within the ventral eye. Light microscopic (LM) reconstructions of the distribution of label in serial longitudinal sections through ventral optic nerves together with electron microscopic (EM) autoradiographic analyses revealed between 70 and 200 efferent axons. The results of these studies and of reconstructions of efferent innervation to photoreceptor somata suggest that each ventral photoreceptor cell or each small cluster of cells is innervated by a separate efferent fiber. Both LM reconstructions and EM analyses showed that efferent fibers ramify extensively and specifically in and near the internal rhabdom of ventral photoreceptor cells. In EM autoradiographs of lateral eyes incubated with 3H- tyramine, the silver grains that were located over ommatidia were concentrated exclusively over efferent fibers. All of these efferent fibers, which lay near rhabdoms and in partitions between retinular cells, were labeled. The results of our present studies support our hypothesis that octopamine is a neurotransmitter in Limulus retinal efferent fibers. This amine may modulate the biochemistry and physiology of ventral photoreceptor cells and may mediate many of the known effects of circadian efferent innervation to the lateral eye.

A chemical ionization gas chromatographic mass spectrometric assay for octopamine and tyramine in rat brain

A method has been developed for the quantitation of the putative phenolamine neurotransmitter octopamine, and its precursor tyramine, in brain tissue. The procedure employs methane chemical ionization of the pentafluoropropionate derivatives of octopamine and tyramine together with the use of deuterated internal standards and selected ion monitoring. Deuterated analogues of octopamine and tyramine are added to brain homogenates in aqueous perchloric acid and ion exchange is used to isolate the brain amines. The method is capable of measuring 20 pg of octopamine and tyramine. The measured concentration (ng g-1 wet tissue) of octopamine and tyramine in rat brain was as follows: whole brain (less cerebellum) (0.6 and 2.2); hypothalamus (3.2 and tyramine value not statistically significant); striatum (0.5 and 11.8) and cortex (0.6 and 1.0). Administration of pargyline resulted in an increase (around ten-fold) in octopamine and tyramine concentration in all the above brain regions. In contrast alpha-methyltyrosine produced only a small increase (50%) in the concentration of tyramine in the striatum.