effect of stress on levels of octopamine,dopamine and serotonin in the American cockroach (Periplaneta americana L.)

1. Various biogenic amines including octopamine, dopamine and serotonin, and their precursors and metabolites in haemolymph and the central nervous system from American cockroaches (Periplaneta americana L.) were measured using electrochemical detection.2. Octopamine was found in similar high relative abundances in haemolymph and the central nervous system.3. The amount of octopamine was much higher than that of tyramine and synephrine in haemolymph and thoracic nerve cord, whereas tyramine was at the highest level followed by octopamine and synephrine in the brain.4. Insects were stressed by vibrating at 100 or 1000 Hz, visually by flashing light at 4 Hz for 15 min or by immersing the insect in water at 60°C for 30 sec, which resulted in the elevation of octopamine, tyramine, synephrine and tyrosine levels in thoracic nerve cord.     

Effects of octopamine, dopamine, and serotonin on production of flight motor output by thoracic ganglia of Manduca sexta

Effects of biogenic amines on a centrally generated motor pattern in Manduca sexta were examined by pressure injecting nanomole to micromole amounts of octopamine, dopamine or serotonin into thoracic ganglia. Motor output was recorded extracellularly from a pair of antagonistic flight muscles and their motor neurons. The monoamines were found to alter production of a motor pattern that produces rhythmic wing flapping (10 Hz) and exhibits phase relationships similar to those in the flight pattern of intact moths. In mesothoracic ganglia with sensory nerves intact, octopamine (4 X 10(-9) mol) injected into lateral regions evoked regular firing of a single motor neuron, whereas a higher dose (4 X 10(-8) mol) often elicited the flight motor pattern. In the absence of sensory input, these doses of octopamine had little effect. Low doses (10(-10) mol) greatly enhanced motor responses to electrical stimulation of a wing sensory nerve. Dopamine (2 X 10(-10) mol) injected into the medial region of the mesothoracic ganglion elicited the flight motor pattern in the presence or absence of sensory input. Rhythmic output induced by dopamine (5 X 10(-10) mol) was suppressed by injecting serotonin (5 X 10(-10) mol) into the same region. These findings demonstrate that dopamine, octopamine, and serotonin have different effects on motor output in Manduca and suggest that these amines are involved in initiating, maintaining and terminating flight behavior, respectively. Octopamine may elicit flight production by enhancing the efficacy of sensory transmission thereby increasing excitability or arousal. Dopamine may act on interneurons involved in generating the flight motor pattern.     

Spectrofluorimetric determination of biogenic amines (serotonin, dopamine) in Metechinorhynchus salmonis (Acanthocephala)

Identification of serotonin and dopamine in M. salmonis was conducted by means of some fluorometric methods. The presence of negligible amount of a serotonin-like component and substance close in its spectral characteristics to dopamine was shown.     

Biogenic amines modulate synaptic transmission between identified giant interneurons and thoracic interneurons in the escape system of the cockroach

In the escape system of the cockroach, Periplaneta americana, a population of uniquely identifiable throacic interneurons (type A or TI_As) receive information about wind via chemical synapses from a population of ventral giant interneurons (vGIs). The TI_As are involved in the integration of sensory information necessary for orienting the animal during escape. It is likely that there are times in an animal's life when it is advantageous to modify the effectiveness of synaptic transmission between the vGIs and the TI_As. Given the central position of the TI_As inthe escape system, this would greatly alter associated motor outputs. We tested the ability of octopamine, serotonin, and dopamine to modulate synaptic transmission between vGIs and TI_As. Both octopamine and dopamine significantly increased the amplitude of vGI-evoked excitatory postsynaptic potentials (EPSPs) in TI_As at 10^?4?10^?2 M, and 10^?3 M, respectively. On the other hand, serotonin significantly decreased the vGI-evoked EPSPs in TI_As at 10^?4?10^?3 M. These results indicate that octopamine, serotonin, and dopamine are capable of modulating the efficacy of transmission of important neural connections within this circuit. © 1992 John Wiley & Sons, Inc.     

Biogenic amines modulate synaptic transmission between identified giant interneurons and thoracic interneurons in the escape system of the cockroach.

In the escape system of the cockroach, Periplaneta americana, a population of uniquely identifiable thoracic interneurons (type A or TIAs) receive information about wind via chemical synapses from a population of ventral giant interneurons (vGIs). The TIAs are involved in the integration of sensory information necessary for orienting the animal during escape. It is likely that there are times in an animal's life when it is advantageous to modify the effectiveness of synaptic transmission between the vGIs and the TIAs. Given the central position of the TIAs in the escape system, this would greatly alter associated motor outputs. We tested the ability of octopamine, serotonin, and dopamine to modulate synaptic transmission between vGIs and TIAs. Both octopamine and dopamine significantly increased the amplitude of vGI-evoked excitatory postsynaptic potentials (EPSPs) in TIAs at 10(-4)-10(-2) M, and 10(-3) M, respectively. On the other hand, serotonin significantly decreased the vGI-evoked EPSPs in TIAs at 10(-4)-10(-3) M. These results indicate that octopamine, serotonin, and dopamine are capable of modulating the efficacy of transmission of important neural connections within this circuit.     

The effects of serotonin and octopamine on behavioral arousal in the crayfish

1. In the crayfish, behavioral arousal is known to elicit walking and to enhance compensatory eye movements.2. To see if serotonin and octopamine modulate arousal, we measured their effects on walking and eye movements in tethered crayfish, Procambarus clarkii. Serotonin strongly suppresses both walking and eye movements.3. In contrast, octopamine elicits an arousal-like state of continuous jittery leg movements and increased eye movements.4. Serotonin's effect on arousal is uncertain, but octopamine remains a plausible modulator of behavioral arousal.     

Presynaptic effects of biogenic amines modulating synaptic transmission between identified sensory neurons and giant interneurons in the first instar cockroach

Intracellular recording was used to investigate the modulatory effects of serotonin and octopamine on the identified synapses between filiform hair sensory afferents and giant interneurons in the first instar cockroach, Periplaneta americana. Serotonin at 10(-4) mol l(-1) to 10(-3) mol l(-1) reduced the amplitude of the lateral axon-to-ipsilateral giant interneuron 3 excitatory postsynaptic potentials. and octopamine at 10(-4) mol l(-1) increased their amplitude. Similar effects were seen on excitatory postsynaptic potentials in dorsal giant interneuron 6. Several lines of evidence suggest that both substances modulate the amplitude of excitatory postsynaptic potentials by acting presynaptically, rather than on the postsynaptic neuron. The fitting of simple binomial distributions to the postsynaptic potential amplitude histograms suggested that, for both serotonin and octopamine, the number of synaptic release sites was being modulated. Secondly, the amplitudes of miniature excitatory postsynaptic potentials recorded in the presence of tetrodotoxin were unaffected by either modulator. Finally, recordings from contralateral giant interneuron 3, which has two identifiable populations of synaptic inputs, showed that each modulator had a more pronounced effect on excitatory postsynaptic potentials evoked by the lateral axon than on those evoked by the medial axon. Immunocytochemistry confirmed that neuropilar processes containing serotonin are present in close proximity to these synapses.     

Titres of biogenic amines and ecdysteroids: effect of octopamine on the production of ecdysteroids in the silkworm Bombyx mori

At day two, a sharp peak of octopamine (OA) was observed in last instar female Bombyx mori larvae. This peak also appeared in male larvae a day later than in females at day three. An OA peak was also observed before the 3rd ecdysis. However, no OA peaks were observed in 4th instar larvae. At day eight and nine of the 5th instar, another OA peak was observed for male and female, respectively. A peak of tyramine (TA) was found at day one followed by a peak of OA at day two in 3rd instar larvae. At day two, a day before OA peak, a peak of TA was observed for male insects and before the 2nd peak of OA, TA titre was also high in 5th instar larvae. Immediately after 3rd ecdysis, a high titre of DL-beta-(3,4-dihydroxyphenyl)alanine (DOPA) was observed, followed by a peak of dopamine (DA) at day five. A peak of DOPA was found at day one followed by a peak of DA at day two in 3rd instar larvae. Similarly, a small peak of DOPA was observed at day two, followed by an increase of DA at days eight and nine after the 4th ecdysis. Ecdysteroid peaks were observed just before the 3rd and 4th ecdysis and an ecdysteroid titre increased after the start of spinning. The effects of OA and JH on production of ecdysteroids by prothoracic glands (PGs) were examined in order to identify neuromediators responsible for triggering pupation in B. mori larvae. Exogeneous OA (10-100 mM) reduced and 10 &mgr;M OA stimulated the production of ecdysteroids in the presence and absence of brain extracts by PGs in the final instar (day five) of B. mori in vitro. Meanwhile, exogeneous JHI (10 &mgr;g/ml) stimulated and at 5 &mgr;g/ml it reduced production of ecdysteroids in the presence of brain extracts. Gramine, an OA antagonist, delayed pupation when applied in the diet. Thus, OA may produce some biological effects on the programming of larval-pupal development.     

Determination of sulfated biogenic amines: emphasis on dopamine sulfate isomers

Investigations concerning the specific conjugates of dopamine (DA) in the body have been hampered by the lack of specific and sensitive methodology for their detection. Because there is increasing interest in the occurrence and measurement of sulfated metabolites of DA and the other catecholamines (CA) norepinephrine and epinephrine, reliable methods for the detection and quantitation of these compounds in biological samples are needed. This paper reviews recently developed methods for the measurement of the two sulfate conjugates of DA in the body, DA-3-O-sulfate and DA-4-O-sulfate. The methods are sensitive enough for most, if not all, routine applications relating to DA sulfate. With minor modifications, some of the methods should be applicable to measurement of sulfate conjugates of many other electrochemically active compounds, such as other CA or indoles, their metabolites, and some drugs and metabolites.     

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.     

Metrifonate effects on acetylcholine and biogenic amines in rat cortex

The effect of systemic and local administration of metrifonate (MTF), a long-acting cholinesterase inhibitor (ChEl) on extracellular levels of acetylcholine (ACh), norepinephrine (NE), dopamine (DA) and serotonin (5-HT) was investigated in the rat cortex by using transcortical microdialysis. Metrifonate (20, 40, and 80 mg/kg, s.c.) increased ACh levels in a dose-dependent manner above the baseline. Two consecutive administrations (80 mg/kg) enhanced ACh levels producing two similar patterns of elevation. A significant increase in NE was also seen at 80 mg/kg. Systemic administration (20 mg/kg) of MTF produced a significant increase of DA levels. Local cortical perfusion of MTF through the probe caused a significant but slow increase of ACh as well as an increase of NE levels. Compared to NE, the elevation of DA was more rapid and more longlasting. The cortical levels of 5-HT were not modified by MTF given by either route. These results support the concept of MTF being a potential drug for treatment of Alzheimer disease (AD).     

Saliva secretion and ionic composition of saliva in the cockroach Periplaneta americana after serotonin and dopamine stimulation,and effects of ouabain and bumetamide

Isolated salivary glands of Periplaneta americana were used to measure secretion rates and, by quantitative capillary electrophoresis, Na(+), K(+), and Cl(-) concentrations in saliva collected during dopamine (1 micro M) and serotonin (1 micro M) stimulation in the absence and presence of ouabain (100 micro M) or bumetanide (10 micro M). Dopamine stimulated secretion of a NaCl-rich hyposmotic saliva containing (mM): Na(+) 95 +/- 2; K(+) 38 +/- 1; Cl(-) 145 +/- 3. Saliva collected during serotonin stimulation had a similar composition. Bumetanide decreased secretion rates induced by dopamine and serotonin; secreted saliva had lower Na(+), K(+) and Cl(-) concentrations and osmolarity. Ouabain caused increased secretion rates on a serotonin background. Saliva secreted during dopamine but not serotonin stimulation in the presence of ouabain had lower K(+) and higher Na(+) and Cl(-) concentrations, and was isosmotic. We concluded: The Na(+)-K(+)-2Cl(-) cotransporter is of cardinal importance for electrolyte and fluid secretion. The Na(+)/K(+)-ATPase contributes to apical Na(+) outward transport and Na(+) and K(+) cycling across the basolateral membrane in acinar P-cells. The salivary ducts modify the primary saliva by Na(+) reabsorption and K(+) secretion, whereby Na(+) reabsorption is energized by the basolateral Na(+)/K(+)-ATPase which imports also some of the K(+) needed for apical K(+) extrusion.     

Perinuclear localization of biogenic amines (serotonin and histamine) in rat immune cells

EDAC fixation, which polymerizes biogenic amines, and clorgyline, which blocks monoamine oxydase, were used to demonstrate the perinuclear and nuclear localization of histamine and serotonin (5-HT) of immune cells in rat peritoneal fluid and thymus. For detection, an immunocytochemical method combined with confocal microscopy was used. In peritoneal cells (lymphocytes) 5-HT formed spots around the nucleus, while histamine was localized diffusely. In thymocytes, 5-HT was distributed in patches, while histamine formed a garland around the nuclear envelope. Clorgyline enhanced the fluorescence and increased the number of fluorescent positive cells only for histamine, and then histamine-positive nuclei were also present. The results show that: (1) EDAC fixation demonstrates the presence of biogenic amines in immune cells, (2) using this fixation, the perinuclear localization of biogenic amines can be demonstrated, (3) the localization of the two amines is different and (4) the nuclear localization of histamine in thymocytes can be surmised and in mast cells (described previously) is proven again. The potential importance of the nuclear and near-nuclear localization of biogenic amines is discussed.     

Activity modulation in cockroach sensillum: the role of octopamine

The plasticity of sensory perception is provided partially by modulation of receptor cells. The electrical activity of American cockroach chemoreceptor cells in response to sex pheromone was measured under the influence of octopamine treatment and tracheal anoxia. Both experimental procedures caused decreased electroantennograms but affected spike activity differently: octopamine treatment increased firing rate, whereas anoxia decreased it. Spike frequency under octopamine treatment was elevated in response to pheromone stimulation and at background activity. Experiments with perfusion of isolated antennae showed a direct effect of octopamine on spike activity of pheromone sensilla, and excluded the possibility of indirect effects via octopamine-dependent release of other biologically active substances. The suggested mechanism of octopamine action is receptor cell membrane depolarization.     

On the haemodynamic effects of biogenic amines in isolated fish gills

The effects of histidine and histamine on branchial vascular haemodynamics were studied using the isolated, perfused gill of the tropical cichlid, Oreochromis (Sarotherodon) niloticus. Histidine had no vasoactive effect while histamine induced vasodilatation. Histamine-induced vasodilatation was irreversibly inhibited by the H1 and H2 receptor antagonists, piriton and cimetidine, respectively. This suggests a possible involvement of the non-neurogenic histaminergic system, acting directly via H1 and H2 histamine receptors, in the regulation of branchial vascular haemodynamics in teleosts.     

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

Summary 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 5·10^-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.Abbreviations 4-AP 4-aminopyridine - CA corpora allata - CC corpora cardiaca - cAMP cyclic adenosine monophosphate - cGMP cyclic guanosine monophosphate - EDTA ethylenediamine tetraacetic acid - HEPES N-2-hydroxyethylpiperazine-N2-ethanesulfonic acid - HPLC high pressure liquid chromatography - IBMX 3-isobutyl-1-methylxanthine - JH juvenile hormone - ms millisecond - nA nanoampere - NCA I nervi corporis allati I - OCT octopamine - TEA tetraethyl ammonium