Presence Of Octopamine Research Articles

Short-term exposure to high pCO2 leads to decreased branchial cytochrome C oxidase activity in the presence of octopamine in a decapod

In a recent mechanistic study, octopamine was shown to promote proton transport over the branchial epithelium in green crabs, Carcinus maenas. Here, we follow up on this finding by investigating the involvement of octopamine in an environmental and physiological context that challenges acid-base homeostasis, the response to short-term high pCO2 exposure (400 Pa) in a brackish water environment. We show that hyperregulating green crabs experienced a respiratory acidosis as early as 6 h of exposure to hypercapnia, with a rise in hemolymph pCO2 accompanied by a simultaneous drop of hemolymph pH. The slightly delayed increase in hemolymph HCO3− observed after 24 h helped to restore hemolymph pH to initial values by 48 h. Circulating levels of the biogenic amine octopamine were significantly higher in short-term high pCO2 exposed crabs compared to control crabs after 48 h. Whole animal metabolic rates, intracellular levels of octopamine and cAMP, as well as branchial mitochondrial enzyme activities for complex I + III and citrate synthase were unchanged in posterior gill #7 after 48 h of hypercapnia. However, application of octopamine in gill respirometry experiments suppressed branchial metabolic rate in posterior gills of short-term high pCO2 exposed animals. Furthermore, branchial enzyme activity of cytochrome C oxidase decreased in high pCO2 exposed crabs after 48 h. Our results indicate that hyperregulating green crabs are capable of quickly counteracting a hypercapnia-induced respiratory acidosis. The role of octopamine in the acclimation of green crabs to short-term hypercapnia seems to entail the alteration of branchial metabolic pathways, possibly targeting mitochondrial cytochrome C in the gill. Our findings help advancing our current limited understanding of endocrine components in hypercapnia acclimation. Summary statementAcid-base compensation upon short-term high pCO2 exposure in hyperregulating green crabs started after 6 h and was accomplished by 48 h with the involvement of the biogenic amine octopamine, accumulation of hemolymph HCO3−, and regulation of mitochondrial complex IV (cytochrome C oxidase).

Presence of octopamine and octopamine receptors in ganglia and tissues of Crassostrea virginica

Octopamine (OA) a biogenic amine first identified in octopus is well studied in arthropods and gastropods being a neurotransmitter and hormone. OA has rarely been reported in bivalves. Using HPLC and ELISA we showed it present in ganglia and tissues of the oyster Crassostrea virginica, the mussel Mytilus edulis, and clam Mercenaria mercenaria. We found it cardio‐excitatory in oyster and mussel, but cardio‐inhibitory in clam. We localized OA and OA receptors in tissues using immunohistofluorescence. We used pan TAAR 1E antibodies, which react to OA, beta‐phenylethylamine, p‐tyramine and tryptamine receptors, but not classical biogenic amines and histamine receptors, and visualized with FITC conjugated 2E antibodies. Tissues were fixed with paraformaldehyde, treated with 1Eand 2Eantibodies, paraffin embedded, sectioned and viewed with a fluorescence microscope. To detect OA we used anti‐OA 1E antibody (OA conjugated to KLH), and visualized with FITC conjugated 2E antibodies. Tissues were fixed with EDAC treated with 1E and 2E antibodies and paraffin embedded and sectioned or frozen, cryostat sectioned and viewed. The TAAR antibodies revealed OA receptors in cerebral and visceral ganglia, heart, gill, adductor muscle and digestive tract. OA antibodies revealed OA in cerebral and visceral ganglia, heart and blood cells in the gill blood channels. The study shows the presence of OA receptors and OA in ganglia and organs of the oyster. The distribution of the OA fluorescence as well as previous HPLC data suggests it may be a hormone in the animal as it appears to be very wide‐spread. The work was supported by 0516041171of NYSDOE and 0622197 of DUE Program of NSF.

Why should an immune response activate the stress response? Insights from the insects (the cricket Gryllus texensis)

Mediators of the stress response (e.g. glucocorticoids and norepinephrine) can be immunosuppressive. Nevertheless, immune challenge leads to the release of these compounds in vertebrates. To resolve this paradox, it has been suggested that stress hormones help restore immune homeostasis, preventing self-damage. A comparative approach may provide additional hypotheses as to why an immune challenge induces the release of stress hormones/neurohormones. Octopamine, a neurohormonal mediator of the stress response in the cricket Gryllus texensis, increased in concentration in the hemolymph during an immune challenge. Therefore, the release of stress hormones during an immune response occurs in animals across phyla. Octopamine induced an increase in lipid concentration in the hemolymph. After an acute stress (flying or running) the total number of hemocytes in the hemolymph increased. Injections of octopamine had the same effect, suggesting that it may enhance hemocyte-dependent immune functions. On the other hand, octopamine decreased lysozyme-like activity in vitro, suggesting that it inhibits some immune functions. However, lysozyme-like activity was increased by the presence of heat-killed bacteria in vitro and this increase was significantly augmented by the presence of octopamine. Therefore, the effect of octopamine on immune function differed depending on the presence of pathogens. Stress hormones may help shift immune function into the most optimal configuration depending on the physiological context.

Octopamine and tyramine modulate pheromone-sensitive olfactory sensilla of the hawkmoth Manduca sexta in a time-dependent manner

In moths octopamine improved pheromone-dependent mate search time dependently. In the nocturnal hawkmoth Manduca sexta long-term tip recordings of trichoid sensilla were performed to investigate whether biogenic amines modulate pheromone transduction time dependently. At three Zeitgebertimes octopamine, tyramine and the octopamine antagonist epinastine were applied during non-adapting pheromone-stimulation. At ZT 8-11, during the photophase, when sensilla were adapted, octopamine and to a lesser extent tyramine increased the bombykal-dependent sensillar potential amplitude and initial action potential (AP) frequency. In addition, during the photophase, when sensilla are less able to resolve pheromone pulses, octopamine rendered pheromone responses more phasic and sensitive, and raised the spontaneous AP frequency. During the late scotophase, at ZT 22-1, when the antenna appeared maximally sensitized for pheromone pulse detection and endogenous octopamine levels are high, exogenously applied octopamine was ineffective. Epinastine blocked the pheromone-dependent AP response at ZT 8-11 and slightly affected it at ZT 22-1, while it had no effect on the sensillar potential amplitude. Epinastine decreased the spontaneous AP activity during photophase and scotophase and rendered pheromone responses more tonic in the scotophase. We hypothesize that the presence of octopamine in the antenna is obligatory for the detection of intermittent pheromone pulses at all Zeitgebertimes.

Physiological Mechanisms of Pheromonostatic Responses: effects of Adrenergic Agonists and Antagonists on Moth (Helicoverpa armigera) Pheromone Biosynthesis

The adrenergic agonists octopamine, tyramine and clonidine inhibited the normal pheromonotropic action due to PBAN (pheromone biosynthesis activating neuropeptide) in incubations of intersegmental tissues that are situated between the 8th and 9th abdominal segments of the moth ovipositor tip. This inhibition was reversed in the presence of the adrenergic antagonists phentolamine, yohimbine and chlorpromazine. Incubations of 8th segments alone, which do not produce pheromone, resulted in elevated levels of intracellular cAMP in the presence of octopamine. The physiological significance of this phenomenon is unclear. However, clonidine (an α2 selective agonist) did not duplicate octopamine stimulation of intracellular cAMP in 8th segment cultures. In intersegmental membrane cultures clonidine successfully duplicated the octopamine inhibition of both pheromone and intracellular cAMP production. The physiological significance of octopaminergic receptors mediating the inhibitory response of intersegments was investigated by experiments in vivo. When PBAN was injected into photophase females the normal pheromonotropic activity due to the injected PBAN dropped after 2h. In the presence of clonidine, normal peak stimulatory levels were never attained and a faster decline was observed. Clonidine also inhibited the pheromonotropic response of 24h-decapitated females to PBAN. Adrenergic antagonists successfully reversed the inhibitory effect of clonidine in decapitated females, but did not reverse the effect of clonidine in photophase females. In addition, when clonidine was injected into female moths during the scotophase normal peak pheromone titers were reduced although no effect on calling behavior was observed. © 1997 Elsevier Science Ltd. All rights reserved

Octopaminergic Innervation and Modulation of a Locust Flight Steering Muscle

We demonstrate that the meso- and metathoracic pleuroaxillary flight steering muscle (M85 mesothorax, M114 metathorax) of the migratory locust are each innervated by a single dorsal unpaired median neurone (DUM3,4,5a). The soma of this neurone can be localized by retrograde staining of the motor nerve with Neurobiotin, but not with cobalt salts. The primary neurite projects in the superficial DUM cell tract, and the axons run in nerve roots 3, 4 and 5 and in all their secondary branches. Other muscle targets include the second tergal remotor coxa (M120) and the posterior rotator coxae (M122, M123, M124), but not the first tergal remotor coxa (M119) and subalar (M129) flight muscles. Octopamine-like immunoreactive varicosities occur on the pleuroaxillary muscles. Stimulation of DUM3,4,5a and octopamine (10(-6) mol l-1) superfusion increased the amplitude and the relaxation velocity of neurally evoked twitch contractions of this muscle. Octopamine also significantly reduced the tonic tension that this muscle develops when stimulated at flight frequency (20 Hz), while increasing the amplitude of each phasic twitch. A catch-like tension is also reduced in the presence of octopamine. Simulations of the motor pattern experienced by the pleuroaxillary muscles during roll manoeuvres suggest that transient changes in tension underlying corrective steering could be doubled in the presence of octopamine.

Octopamine induces steady-state reflex reversal in crayfish thoracic ganglia.

1. This paper investigates the effect of octopamine on spontaneous and reflex motor output of crayfish leg motor neurons. Octopamine modulated spontaneous activity, both rhythmic and tonic, and dramatically modulated the pattern of reflex motor output elicited by stimulating identified proprioceptors of the basal limb. 2. Spontaneous reciprocal motor patterns, involving alternating bursts of promotor and remotor motor neuron activity, were reversibly abolished by octopamine. The threshold concentration for this effect was approximately 1 microM. 3. At concentrations greater than approximately 10 microM octopamine inhibited spontaneous promotor nerve activity in both bursting and nonbursting preparations. In some experiments promotor inhibition was correlated with the induction of tonic remotor nerve activity. The EC50 for complete inhibition of promotor nerve activity by octopamine was 20-30 microM. 4. Reflexes mediated by two basal limb proprioceptors, the thoracocoxal muscle receptor organ (TCMRO; which signals leg promotion) and the thoracocoxal chordotonal organ (TCCO; which signals leg remotion) were analyzed in a number of promotor and remotor motor neurons. In both cases assistance reflexes (excitation of promotors by the TCCO and remotors by the TCMRO) were restricted to subgroups of the motor pool. Among remotor motor neurons, the first two units recruited during bursts of spontaneous activity were members of the assistance reflex group (group 1). A third unit, sometimes recruited during more intense spontaneous bursts, was excited by TCCO stimulation and was therefore a member of the resistance reflex group (group 2). Other resistance group remotors were also excited by the TCCO, but this input normally remained subthreshold. 5. Stimulation of the TCCO afferent nerve elicited excitatory postsynaptic potentials (EPSPs) in group 2 (resistance group) remotor motor neurons at a latency compatible with a monosynaptic connection. The same stimulation excited group 1 (assistance group) promotor motor neurons, but at a greater and more variable latency. Thus the remotor resistance reflex from the TCCO is probably monosynaptic, but the promotor assistance reflex, also elicited by TCCO stimulation, is likely to be di- or polysynaptic. Assistance group (group 1) remotor motor neurons are inhibited by mechanical stimulation of the TCCO, or electrical stimulation of its nerve. 6. Octopamine had selective effects on individual remotor units. First, assistance group remotor motor neurons were affected in two ways. One unit was inhibited, so that reflex spiking in response to TCMRO stimulation was abolished. A second unit was not inhibited, but its reflex response mode changed, so that instead of responding to TCMRO input with an assistance reflex, it responded to TCCO input with a resistance reflex. Second, among motor neurons that normally respond to TCCO input with resistance reflexes, these responses were enhanced by octopamine. 7. Promotor motor neurons were inhibited by octopamine and reflex responses were also affected selectively. Responses to TCCO input (assistance reflexes) were abolished; whereas, responses to TCMRO input (resistance reflexes) were relatively less affected. 8. Intracellular recordings revealed that the majority of remotor motor neurons depolarized in the presence of octopamine. In preparations where these could be classified on the basis of TCMRO/ TCCO inputs, all were identified as group 2 (resistance group). A minority of remotor motor neurons were hyperpolarized by octopamine. All of these were identified as group 1 (assistance group), with strong TCMRO input. 9. The majority of promotor motor neurons were depolarized by octopamine. This depolarization was nevertheless inhibitory since it reversed slightly positive to rest and was associated with a substantial fall in inp

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.

Dopamine-beta-hydroxylase-like immunoreactive neurons in two insect species, Calliphora erythrocephala and Periplaneta americana.

The localization of dopamine-beta-hydroxylase in the cephalic central nervous system of the blowfly (Calliphora erythrocephala) and the cockroach (Periplaneta americana) was investigated. Immunoreactive neurons were demonstrated in both species. The results were compared with the known distribution of catecholamines in the brain of both species. In certain cell groups and neuropilar regions of both species D beta H-immunoreactivity coincides with the presence of catecholamines. Additionally D beta H immunoreactivity was found in several cell bodies and neuropilar regions in which no catecholamines could be detected. A correlation between the presence of octopamine and anti-D beta H labelling was not found. Thus it seems that the D beta H-immunoreactivity neither indicates the presence of octopamine nor is it limited to noradrenaline-containing neurons. Parallel findings in vertebrates are discussed.

Presence of octopamine in firefly photomotor neurons

Various tissues involved in producing luminescence in larval fireflies ( Photuris versicolor) were examined for the presence of octopamine. These tissues included the terminal abdominal ganglion (A8) which innervates the paired lantern organs, the cell bodies of the photomotor neurons and the isolated larval lanterns. A previous study has identified the 4 motoneurons arising from A8 which bilaterally innervate the paired larval lanterns through symmetrical axons existing both sides of the ganglion. Individual photomotor neuron somata were isolated, pooled and found to contain about 0.03 pmol/soma, giving an effective concentration of 2.8 mM octopamine. Significant amounts of octopamine were also found within the peripheral effector tissue. The presence of octopamine throughout the luminescence-producing pathway further supports the hypothesis that octopamine serves a neurotransmitter function in firefly bioluminescence. In this system, it appears that octopamine serves a more direct role as a neurotransmitter than that postulated for its modulatory and hormonal functions in other arthropod systems. Furthermore, the bioluminescent response of the larval firefly lantern provides a useful dynamic system to study the physiology, pharmacology and biochemistry of octopaminergic transmission.

Potentiation of Neuromuscular Transmission by An Octopaminergic Neurone in the Locust

ABSTRACT Spikes in the octopaminergic dorsal unpaired median (DUM) neurone which innervates the extensor tibiae muscle of the locust metathoracic leg (DUMETi) produce direct and indirect effects on muscle tension. Direct effects include a slowing of an intrinsic rhythm of contraction and relaxation, a relaxation of muscle tone and a small hyperpolarization of the muscle membrane potential. The latter two effects are weak and variable. All three effects are mimicked by superfusion of octopamine and are mediated by octopamine receptors on the muscle fibres. Indirect effects are found when the DUMETi neurone is stimulated at the same time as the motoneurones innervating the extensor muscle. They include (a) potentiation of tension generated in the extensor muscle by spikes in the slow excitatory motoneurone (SETi), (b) reduction in duration of each twitch contraction generated by SETi due to an increase in the rate at which the muscle relaxes, (c) increase in the amplitude of the synaptic potential generated by SETi. These various effects have a time course of several minutes and far outlast the duration of DUMETi stimulation. They can be mimicked by superfusion of octopamine. The effect of DUMETi on neuromuscular transmission is mediated by receptors with a high affinity for octopamine located both on the muscle and on the terminals of the slow motoneurone. The presence of the presynaptic receptors is revealed by the increase in the frequency of spontaneous miniature end plate potentials recorded in the muscle in the presence of octopamine. DUMETi is a member of a group of similar aminergic neurones and it is suggested that they may share a role in modulating transmission at peripheral neuromuscular synapses, and possibly central synapses.

The normal occurrence of octopamine in the central nervous system of the rat

An enzymatic assay for octopamine capable of detecting 50 pg of amine was developed and used to study the distribution of octopamine in regions of the rat central nervous system. The presence of octopamine in the rat pineal organ was confirmed by mass spectrometry. Administration of a monoamine oxidase inhibitor and of tyramine led to increases in CNS octopamine levels while the administration of reserpine intraperitoneally or 6-hydroxydopamine intraventricularly led to decreases in octopamine levels. The results suggest that in the mammalian CNS octopamine is present in neural structures where it may be involved in synaptic function.

The presence of octopamine in the brain of Helix aspersa and its action on specific snail neurones.

L'octopamine est presente dans le tissue nerveus l'escargot,Helix aspersa. Elle a un effet fortement inhibitoire sur certains neurones. Ces neurones sont aussi sensibles a la dopamine et a la noradrenaline. Le mecanisme possible de l'action de l'octopamine est discute.

Octopamine in the lobster nervous system.

A search for catecholamines which might serve as transmitters in the lobster nervous system demonstrated only small amounts of dopamine (about 0.2 µg/g tissue) and failed to detect noradrenaline or adrenaline (limit of sensitivity, 0.1 µg g−1) (unpublished results of D. L. B., using standard procedures for isolation of catecholamines on alumina1 and fluorescence assays1,2). Octopamine (the phenol analogue of noradrenalin, Fig. 1) occurs in large amounts in the posterior salivary glands of Octopus vulgaris3 and recently has been identified as a normal minor constituent of sympathetically innervated tissues of rat4. The possible occurrence of octopamine or other phenolamines in the lobster was therefore investigated. Here we report the presence of octopamine in the lobster nervous system, its endogenous distribution and its biosynthesis from tyrosine.

TISSUE DISTRIBUTION OF EXOGENOUSLY ADMINISTERED, AND ENDOGENOUSLY ACCUMULATED OCTOPAMINE IN RATS

The presence of octopamine in the secretion of the salivary gland of Octopus vulgaris was first demonstrated by Erspamer (1). Kakimoto and Armstrong (2) showed the occurrence of this amine in various tissues of rabbits treated with monoamine oxidase inhibitors. However, paper chromatographic studies of the tissue level of octopamine did not give precise information about small changes of the amine level. Based upon the reaction that octopamine is converted quantitatively to p-hydroxybenzaldehyde by periodate oxidation in ammonia alkaline medium (3), the amount of tissue and blood octopamine could be evaluated by measuring the ultraviolet absorption of the oxidation product. In the present experiments the distribution of exogenously administered octopamine and the accumulation of endogenous octopamine after a monoamine oxidase inhibitor were studied in the blood, brain stem, heart, submaxillary glands, spleen and stomach of the rat.