Brain biogenic amines and reproductive dominance in bumble bees (Bombus terrestris)

To begin to explore the role of biogenic amines in reproductive division of labor in social insects, brain levels of dopamine, serotonin, and octopamine were measured in bumble bee (Bombus terrestris) workers and queens that differ in behavioral and reproductive state. Levels of all three amines were similar for mated and virgin queens. Young workers that developed with or without a queen had similar amine levels, but in queenright colonies differences in biogenic amine levels were associated with differences in behavior and reproductive physiology. Dominant workers had significantly higher octopamine levels compared with workers of lower dominance status but of similar size, age, and ovary state. High dopamine levels were associated with the last stages of oocyte development irrespective of worker social status and behavior. These results suggest that biogenic amines are involved in behavioral and physiological aspects of regulation of reproduction in bumble bees. Accepted: 10 December 1999     

Different effects of the biogenic amines dopamine,serotonin and octopamine on the thoracic and abdominal portions of the escape circuit in the cockroach

1. The escape behavior of the cockroach, Periplaneta americana, is known to be modulated under various behavioral conditions (Camhi and Volman 1978; Camhi and Nolen 1981; Camhi 1988). Some of these modulatory effects occur in the last abdominal ganglion (Daley and Delcomyn 1981a, b; Libersat et al. 1989) and others in the thoracic ganglia (Camhi 1988). Neuromodulator substances are known to underlie behavioral modulation in various animals. Therefore, we have sought to determine whether topical application of putative neuromodulators of the escape circuit enhance or depress this circuit, and whether these effects differ in the last abdominal vs. the thoracic ganglia. 2. Topical application of the biogenic amines serotonin and dopamine to the metathoracic ganglion modulates the escape circuitry within this ganglion; serotonin decreases and dopamine enhances the response of leg motoneurons to activation of interneurons in the abdominal nerve cord by electrical or wind stimulation. 3. The neuropil of the thoracic ganglia contains many catecholamine-histofluorescent processes bearing varicosities, providing a possible anatomical substrate for dopamine release sites. 4. Topical application of octopamine to the terminal abdominal ganglion enhances the response of abdominal interneurons to wind stimulation of the cerci. In contrast, serotonin and dopamine have no effect at this site. 5. It is proposed that release of these biogenic amines may contribute to the known modulation of the cockroach escape response.     

Biogenic amines modulate pulse rate in the dorsal blood vessel of Lumbriculus variegatus

The biogenic amines are widespread regulators of physiological processes, and play an important role in regulating heart rate in diverse organisms. Here, we present the first pharmacological evidence for a role of the biogenic amines in the regulation of dorsal blood vessel pulse rate in an aquatic oligochaete, Lumbriculus variegatus (Müller, 1774). Bath application of octopamine to intact worms resulted in an acceleration of pulse rate, but not when co-applied with the adenylyl cyclase inhibitor MDL-12,330a. The phosphodiesterase inhibitor theophylline mimicked the effects of OA, but the polar adenosine receptor antagonist 8(p-sulphophenyl)theophylline was significantly less potent than theophylline. Pharmacologically blocking synaptic reuptake of the biogenic amines using the selective 5-HT reuptake blocker fluoxetine or various tricyclic antidepressants also accelerated heart rate. Depletion of the biogenic amines by treatment with the monoamine vesicular transporter blocker reserpine dramatically depressed pulse rate. Pulse rate was partially restored in amine-depleted worms after treatment with octopamine or dopamine, but fully restored following treatment with serotonin. This effect of 5-HT was weakly mimicked by 5-methoxytryptamine, but not by α-methylserotonin; it was completely blocked by clozapine and partially blocked by cyproheptadine. Because they are known to orchestrate a variety of adaptive behaviors in invertebrates, the biogenic amines may coordinate blood flow with behavioral state in L. variegatus.     

The fight and flight responses of crickets depleted of biogenic amines

Aggressive and escape behaviors were analysed in crickets (Orthoptera) treated with either reserpine, a nonspecific depleter of biogenic amines, or the synthesis inhibitors alpha-methyltryptophan (AMTP) and alpha-methyl-p-tyrosine (AMT) to specifically deplete serotonin, respectively dopamine and octopamine. Standard immunocytochemical techniques were used to verify depletion from central nervous tissue, and determine the effective dosages. Reserpinized crickets became exceedingly lethargic and had severely depressed escape responses. However, they were still able to express all the major elements of the escalating sequences of stereotype motor performances that typifies normal aggressive behavior in the cricket. AMT and AMTP treatment had opposing influences on escape behavior, being enhanced by serotonin depletion, but depressed by dopamine/octopamine depletion. AMTP-induced serotonin depletion had no influence on aggressive or submissive behaviors. AMT-treated crickets could normally only be brought to fight by coaxing. Though capable of expressing aggressive behavior per se, agonistic encounters between AMT-treated crickets were shorter, and rarely involved actual physical interactions. Hence, although amines seem to have similar actions on escape behavior in insects and crustaceans, the aminergic control of aggression seems to be fundamentally different in these arthropods groups. We conclude that amines are not in principle required for the initiation and operation of the motor circuits underlying aggression in the cricket. However, octopamine and/or dopamine seem necessary for establishing a level of excitability sufficient for aggressive behavior to become overt in response to appropriate natural releasing stimuli.     

Biogenic amines and division of labor in honey bee colonies: behaviorally related changes in the antennal lobes and age-related changes in the mushroom bodies

Levels of the biogenic amines dopamine, serotonin, and octopamine were measured in different brain regions of adult worker honey bees as a function of age-related division of labor, using social manipulations to unlink age and behavioral state. In the antennal lobes, foragers had higher levels of all three amines than nurses, regardless of age. Differences were larger for octopamine than serotonin or dopamine. In the mushroom bodies, older bees had higher levels of all three amines than younger bees, regardless of behavioral state. These correlative results suggest that increases in octopamine in the antennal lobes may be particularly important in the control of age-related division of labor in honey bees. Accepted: 10 February 1999     

Serotonin and octopamine elicit stereotypical agonistic behaviors in the squat lobster Munida quadrispina (Anomura, Galatheidae)

Serotonin and octopamine have been implicated as modulators of posture and behavior in several crustaceans. Here we characterize the agonistic behaviors of normally interacting squat lobsters Munida quadrispina (Anomura, Galatheidae) and their responses to serotonin and octopamine injected into the ventral hemolymph sinus, in order to evaluate the potential roles of these amines in modulating agonistic behaviors. Normally interacting M. quadrispina do not develop lasting dominance hierarchies, although transient aggressive and submissive displays do occur. Injected serotonin elicits postures and behaviors in isolated individuals similar to those typical of aggressive, normally interacting animals. Injected octopamine can produce postures and behaviors typical of submissive animals, and elicits behaviors which imply a modulatory role for octopamine in tailflipping. The effects of both amines are reversible and dose dependent, and the dose-response curves parallel the normal progression of agonistic interactions. The social behaviors and reactions to injected serotonin and octopamine of M. quadrispina differ from those of lobsters and crayfish, indicating that interspecific differences in neuromodulation of behavior and motor output exist. Such differences have implications for the understanding of aminergic modulation of aggression and the evolution of aminergic modulation in crustaceans. Accepted: 22 June 1997     

Octopamine and serotonin have opposite effects on antipredator behavior in the orb-weaving spider, <Emphasis Type="Italic">Larinioides cornutus</Emphasis>

In this study, we experimentally elevated levels of octopamine and serotonin in an orb-weaving spider, and observed the effects on the antipredator behavior thanatosis (death feigning), activity level, and running speed. We found that octopamine significantly shortened the duration of thanatosis, and its effect wore off over 24 h. We also found that serotonin significantly lengthened thanatosis, but in this case, the effect persisted for over 24 h. Neither octopamine nor serotonin affected the general activity or running speed of the spiders. To our knowledge, this is the first study to directly explore the role of biogenic amines on a specific antipredator behavior in spiders. Given that spiders must be both aggressive toward prey, yet wary of predators, we believe that this system will be an outstanding model to explore connections between behavioral ecology and neurochemistry.     

IP3-mediated octopamine-induced synaptic enhancement of crayfish LG neurons

The biogenic amines, octopamine and serotonin, modulate the synaptic activity of the lateral giant interneuron (LG) circuitry of the crayfish escape behavior. Bath application of both octopamine and serotonin enhances the synaptic responses of LG to sensory stimulation. We have shown previously (Araki et al. J Neurophysiol 94:2644-2652, 2005) that a serotonin-induced enhancement of the LG response was mediated by an increase in cAMP levels following activation of adenylate cyclase; however, octopamine acts independently. Here, we clarify how octopamine enhances the LG response during sensory stimulation using physiological and pharmacological analyses. When phospholipase C inhibitor U-73122 was directly injected into the LG before biogenic amine application, it abolished the enhancing effect of octopamine on direct sensory input to the LG, but did not block indirect input via sensory interneurons or the effect of serotonin. Direct injection of IP(3), and its analogue adenophostin A, into the LG increased the synaptic response of the LG to sensory stimulation. Thus, IP(3) mediates octopamine-induced synaptic enhancement of the LG, but serotonin acts independently. These results indicate that both octopamine and serotonin enhance the synaptic responses of the LG to sensory stimulation, but that they activate two different signaling cascades in the LG.     

Drosophila Vesicular Monoamine Transporter Mutants Can Adapt to Reduced or Eliminated Vesicular Stores of Dopamine and Serotonin

Physiologic and pathogenic changes in amine release induce dramatic behavioral changes, but the underlying cellular mechanisms remain unclear. To investigate these adaptive processes, we have characterized mutations in the Drosophila vesicular monoamine transporter (dVMAT), which is required for the vesicular storage of dopamine, serotonin, and octopamine. dVMAT mutant larvae show reduced locomotion and decreased electrical activity in motoneurons innervating the neuromuscular junction (NMJ) implicating central amines in the regulation of these activities. A parallel increase in evoked glutamate release by the motoneuron is consistent with a homeostatic adaptation at the NMJ. Despite the importance of aminergic signaling for regulating locomotion and other behaviors, adult dVMAT homozygous null mutants survive under conditions of low population density, thus allowing a phenotypic characterization of adult behavior. Homozygous mutant females are sterile and show defects in both egg retention and development; males also show reduced fertility. Homozygotes show an increased attraction to light but are mildly impaired in geotaxis and escape behaviors. In contrast, heterozygous mutants show an exaggerated escape response. Both hetero- and homozygous mutants demonstrate an altered behavioral response to cocaine. dVMAT mutants define potentially adaptive responses to reduced or eliminated aminergic signaling and will be useful to identify the underlying molecular mechanisms.     

Presynaptic effects of octopamine, serotonin, and cocktails of the two modulators on neuromuscular transmission in crustaceans

The effect of the biogenic amines octopamine and serotonin, and of both amines combined (cocktails) on transmitter release at neuromuscular junctions of two crustaceans was studied. octopamine (10(-8) mol l(-1) to 10(-6) mol l(-1)) either enhanced or decreased evoked transmitter release through presynaptic effects. The results were identical for the slow and the fast excitor in the closer muscle of the crab, and for the excitor in the opener muscle of the crayfish. Application of serotonin always resulted in a strong increase of release. However, this potentiating effect of serotonin was reduced in strength by subsequent application of cocktails consisting of serotonin and octopamine. In all experiments, a cocktail of serotonin and octopamine was less effective than serotonin alone. The decrease in the mean quantal content m by octopamine was due to a reduction of the probability of release p. Since both amines are synthesized in the central nervous system and are released from neurohaemal organs into the haemolymph bathing the neuromuscular junctions, the results suggest that the two amines, when present together, modulate transmitter release in an antagonistic way, and that the level of the two determines synaptic efficacy.     

To swim or not to swim: regional effects of serotonin, octopamine and amine mixtures in the medicinal leech

Focally treating the head brain of the medicinal leech Hirudo medicinalis with various biogenic amines affected the initiation, termination and maintenance of fictive swimming (i.e., the neural correlate of swimming). Application of serotonin to saline surrounding only the head brain inhibited fictive swimming, whereas removing serotonin induced swimming. This contrasts sharply with previous observations that serotonin applied to the nerve cord induces swimming. Although application of octopamine to the brain activated swimming, a mixture of octopamine and serotonin inhibited swimming. Subsequent removal of this mixture from the brain activated robust swimming and was more potent for activating swimming than either the removal of serotonin or the application of octopamine. Swim episodes induced by brain-specific manipulations of octopamine had more swim bursts per episode than those induced by serotonin. These brain-specific effects of the amines on fictive swimming are probably due to the modulation of higher-order circuits that control locomotion in the leech. We observed that serotonin or a mixture of serotonin and octopamine hyperpolarized an identified descending brain interneuron known as Tr2. Removal of the mixture caused Tr2 to exhibit membrane potential depolarizations that correlated in time with the expression of swim episodes.     

Tyramine and octopamine have opposite effects on the locomotion of Drosophila larvae

Biogenic amines are believed to play important roles in producing behaviors. Although some biogenic amines have been extensively studied in both vertebrates and invertebrates, little is known about the effects of trace amines like tyramine and octopamine. We investigated how trace amines affect behaviors using quantitative morphometric methods on Drosophila Tbetah(nM18) and iav(N) mutants that have altered levels of tyramine and octopamine. Locomotion of wild-type and mutant third instar larvae was analyzed using Dynamic Image Analysis System (DIAS) software. We found that Tbetah(nM18) mutants, with elevated tyramine levels and reduced octopamine levels, had a severe locomotion phenotype. Mutant larvae spent much more time in pausing episodes than wild-type larvae and displayed a reduction in speed and linear translocation. The locomotion phenotype was partially rescued by feeding Tbetah(nM18) larvae octopamine, an effect that could be nullified with simultaneous feeding of tyramine. Feeding Tbetah(nM18) larvae yohimbine, an agent that inhibits the activity of Drosophila tyramine receptors, also improved some locomotion parameters. Feeding both octopamine and yohimbine further improved rescue efficiency. Simultaneously reducing the octopamine and tyramine levels as in iav(N) larvae, in contrast, led to a less severe behavioral phenotype than that of Tbetah(nM18) mutants. Feeding iav(N) larvae either tyramine or octopamine exerted only a minor improvement in locomotion. These results suggest that tyramine and octopamine have opposite effects on Drosophila larval locomotion regulation and that a balance between the two is important in producing normal behavior.     

Differential effects of octopamine and tyramine on the central pattern generator for <Emphasis Type="Italic">Manduca</Emphasis> flight

The biogenic amine, octopamine, modulates a variety of aspects of insect motor behavior, including direct action on the flight central pattern generator. A number of recent studies demonstrate that tyramine, the biological precursor of octopamine, also affects invertebrate locomotor behaviors, including insect flight. However, it is not clear whether the central pattern generating networks are directly affected by both amines, octopamine and tyramine. In this study, we tested whether tyramine affected the central pattern generator for flight in the moth, Manduca sexta. Fictive flight was induced in an isolated ventral nerve cord preparation by bath application of the octopamine agonist, chlordimeform, to test potential effects of tyramine on the flight central pattern generator by pharmacological manipulations. The results demonstrate that octopamine but not tyramine is sufficient to induce fictive flight in the isolated ventral nerve cord. During chlordimeform induced fictive flight, bath application of tyramine selectively increases synaptic drive to depressor motoneurons, increases the number of depressor spikes during each cycle and decreases the depressor phase. Conversely, blocking tyramine receptors selectively reduces depressor motoneuron activity, but does not affect cycle by cycle elevator motoneuron spiking. Therefore, octopamine and tyramine exert distinct effects on the flight central pattern generating network.     

Octopamine and tyramine influence the behavioral profile of locomotor activity in the honey bee (Apis mellifera)

The biogenic amines octopamine and tyramine are believed to play a number of important roles in the behavior of invertebrates including the regulation of motor function. To investigate the role of octopamine and tyramine in locomotor behavior in honey bees, subjects were injected with a range of concentrations of octopamine, tyramine, mianserin or yohimbine. Continuous observation of freely moving worker bees was used to examine the effects of these treatments on the amount of time honey bees spent engaged in different locomotor behaviors such as walking, grooming, fanning and flying. All treatments produced significant shifts in behavior. Decreases in time spent walking and increases in grooming or stopped behavior were observed for every drug. However, the pattern of the shift depended on drug, time after injection and concentration. Flying behavior was differentially affected with increases in flying seen in octopamine treated bees, whereas those receiving tyramine showed a decrease in flying. Taken together, these data provide evidence that octopamine and tyramine modulate motor function in the honey bee perhaps via interaction with central pattern generators or through effects on sensory perception.     

Place memory formation in Drosophila is independent of proper octopamine signaling

The biogenic amines play a critical role in establishing memories. In the insects, octopamine, dopamine, and serotonin have key functions in memory formation. For Drosophila, octopamine is necessary and sufficient for appetitive olfactory memory formation. Whether octopamine plays a general role in reinforcing memories in the fly is not known. Place learning in the heat-box associates high temperatures with one part of a narrow chamber, and a cool, strongly preferred temperature with the other half of the chamber. The cool-temperature-associated chamber half could provide a rewarding stimulus to a fly, and thus a place memory is composed of an aversive and rewarded memory component. The role of octopamine in place memory was thus tested. Using a mutation in the tyramine beta hydroxylase (TβH[M18]) and blocking of evoked synaptic transmission in the octopamine (and tyramine) neurons labeled with a tyramine decarboxylase-2 (TDC2) gene regulatory elements we found that reinforcement of place memories is independent of normal octopamine signaling. Thus, reinforcing mechanisms in Drosophila have specialized systems in the formation of specific memory types.     

Cloning and expression pattern of a putative octopamine/tyramine receptor in antennae of the noctuid moth <Emphasis Type="Italic">Mamestra brassicae</Emphasis>

In insects, biogenic amines have been shown to play an important role in olfactory plasticity. In a first attempt to decipher the underlying molecular mechanisms, we report the molecular cloning and precise expression pattern of a newly identified octopamine/tyramine-receptor-encoding gene in the antennae of the noctuid moth Mamestra brassicae (MbraOAR/TAR). A full-length cDNA has been obtained through homology cloning in combination with rapid amplification of cDNA ends/polymerase chain reaction; the deduced protein exhibits high identities with previously identified octopamine/tyramine receptors in other moths. In situ hybridization within the antennae has revealed that MbraOAR/TAR is expressed at the bases of both pheromone-sensitive and non-sensitive olfactory sensilla and in cells with a neurone-like shape. In accordance with previous physiological studies that have revealed a role of biogenic amines in the electrical activity of the receptor neurones, our results suggest that biogenic amines (either octopamine or tyramine) target olfactory receptor neurones to modulate olfactory coding as early as the antennal level.     

Biogenic amines in the two-spotted spider mite

Whole body extracts of the two-spotted spider mite (Tetranychus urticae Koch) were analyzed using a 16-channel electrochemical array high performance liquid chromatography (HPLC)-based detection system that allows the simultaneous isolation and identification of a variety of biogenic amines. The spider mite extracts were found to contain the biogenic amines octopamine, dopamine, and 5-hydroxytryptamine (5-HT), as well as several precursors and metabolites including tyrosine, tyramine, tryptophan, and N-acetyl octopamine. Differences in the levels of biogenic amines were observed between eggs and the adult stages and between males and females. This is the first direct determination of biogenic amines in the Tetranychidae and the first demonstration of 5-HT in any mite species. © 1994 Wiley-Liss, Inc.     

昆虫体内章鱼胺的分布、功能及其研究进展

章鱼胺是无脊椎动物神经系统中普遍存在的多种微量生物胺之一。章鱼胺的分布及含量变化对于昆虫的生长、取食、代谢等多种生理、生物效应具有重要的作用。文章对昆虫体内章鱼胺的功能性、昆虫体内章鱼胺的分布及其主要功能、章鱼胺痕量测定方法、生存环境的改变及化学药剂的作用对章鱼胺含量的影响以及外界刺激对章鱼胺含量影响的生理及生物化学机理研究进行了综述。     

Dispensable,Redundant, Complementary,and Cooperative Roles of Dopamine,Octopamine, and Serotonin in Drosophila melanogaster

To investigate the regulation of Drosophila melanogaster behavior by biogenic amines, we have exploited the broad requirement of the vesicular monoamine transporter (VMAT) for the vesicular storage and exocytotic release of all monoamine neurotransmitters. We used the Drosophila VMAT (dVMAT) null mutant to globally ablate exocytotic amine release and then restored DVMAT activity in either individual or multiple aminergic systems, using transgenic rescue techniques. We find that larval survival, larval locomotion, and female fertility rely predominantly on octopaminergic circuits with little apparent input from the vesicular release of serotonin or dopamine. In contrast, male courtship and fertility can be rescued by expressing DVMAT in octopaminergic or dopaminergic neurons, suggesting potentially redundant circuits. Rescue of major aspects of adult locomotion and startle behavior required octopamine, but a complementary role was observed for serotonin. Interestingly, adult circadian behavior could not be rescued by expression of DVMAT in a single subtype of aminergic neurons, but required at least two systems, suggesting the possibility of unexpected cooperative interactions. Further experiments using this model will help determine how multiple aminergic systems may contribute to the regulation of other behaviors. Our data also highlight potential differences between behaviors regulated by standard exocytotic release and those regulated by other mechanisms.