TY - GEN A1 - Scheiner, Ricarda A1 - Baumann, Arnd A1 - Blenau, Wolfgang T1 - Aminergic control and modulation of honeybee behaviour N2 - Biogenic amines are important messenger substances in the central nervous system and in peripheral organs of vertebrates and of invertebrates. The honeybee, Apis mellifera, is excellently suited to uncover the functions of biogenic amines in behaviour, because it has an extensive behavioural repertoire, with a number of biogenic amine receptors characterised in this insect. In the honeybee, the biogenic amines dopamine, octopamine, serotonin and tyramine modulate neuronal functions in various ways. Dopamine and serotonin are present in high concentrations in the bee brain, whereas octopamine and tyramine are less abundant. Octopamine is a key molecule for the control of honeybee behaviour. It generally has an arousing effect and leads to higher sensitivity for sensory inputs, better learning performance and increased foraging behaviour. Tyramine has been suggested to act antagonistically to octopamine, but only few experimental data are available for this amine. Dopamine and serotonin often have antagonistic or inhibitory effects as compared to octopamine. Biogenic amines bind to membrane receptors that primarily belong to the large gene-family of GTP-binding (G) protein coupled receptors. Receptor activation leads to transient changes in concentrations of intracellular second messengers such as cAMP, IP3 and/or Ca2+. Although several biogenic amine receptors from the honeybee have been cloned and characterised more recently, many genes still remain to be identified. The availability of the completely sequenced genome of Apis mellifera will contribute substantially to closing this gap. In this review, we will discuss the present knowledge on how biogenic amines and their receptor-mediated cellular responses modulate different behaviours of honeybees including learning processes and division of labour. KW - Serotonin KW - dopamine KW - octopamine KW - tyramine KW - honeybee Y1 - 2006 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-46106 ER - TY - THES A1 - Hille, Carsten T1 - Charakterisierung von Transportmechanismen in der Speicheldrüse der Schabe Periplaneta americana T1 - Characterisation of transport mechanisms in salivary glands of the cockroach Periplaneta americana N2 - Die Aktivierung der Speichelsekretion erfolgt in der innervierten Speicheldrüse der Schabe Periplaneta americana durch die biogenen Amine Dopamin (DA) und Serotonin (5-HT). Die Acini der Speicheldrüse sezernieren einen Primärspeichel, der in den Ausführgängen modifiziert wird. Die durch DA und 5-HT aktivierten Signalwege sowie die an der Elektrolyt- und Flüssigkeitssekretion bzw. Speichel-modifikation beteiligten Transportmechanismen sind weitgehend unbekannt. Mikrofluorometrische Ca2+-, Na+- und pH-Messungen in Kombination mit pharmakologischen Experimenten, biochemische Messungen der Aktivitäten von Ionentransport-ATPasen sowie videomikroskopische Analysen zu transepithelialen Wasserbewegungen wurden in dieser Arbeit durchgeführt. Sie sollten Informationen über die an der Speichelbildung und -modifikation beteiligten Transportmechanismen und die Signalwege liefern, welche durch DA und/oder 5-HT aktiviert werden. Wesentliche Ergebnisse dieser Arbeit waren: Diese Arbeit trug zur Kenntnis der komplexen Funktionsweise von Speicheldrüsen in Insekten bei und erweiterte das lückenhafte Wissen über die zellulären Wirkungen biogener Amine in Insekten. Zudem wurden in dieser Arbeit viele Parallelen zu Funktionsweisen der Speicheldrüsen in Vertebraten deutlich. N2 - The acinar salivary glands in the cockroach Periplaneta americana are innervated by dopaminergic and serotonergic fibers and secrete a NaCl-rich primary saliva upon stimulation with the biogenic amines dopamine (DA) or serotonin (5-HT). The ducts downstream of the acini are thought to modify the primary saliva by Na+ reabsorption and K+ secretion. The electrolyte and fluid transport processes activated by DA and 5-HT as well as the second messenger pathways mediating between the biogenic amine receptors and the effector transport mechanisms are poorly understood.In this sudy, microfluorometrical Ca2+, Na+ and pH measurements were performed in combination with pharmacological experiments. Furthermore, ATPase activity assays and microscopical analyses of transepithelial fluid transport were done. The aim of this work has been the characterisation of the DA-induced transport mechanisms in the cockroach salivary glands in order to improve our understanding of the cellular actions of biogenic amines in insects. Intracellular pH measurements in duct cells of isolated small lobes of salivary glands consiting of several acini and ducts showed a strong intracellular acidification upon DA or 5-HT stimulation. On the other hand, only a small intracellular acidification could be recognised in isolated ducts without acini. The acini are innervated by dopaminergic and serotonergic fibers, whereas the ducts are innervated only by dopaminergic fibers. Thus, this result demonstrates, that the DA- or 5-HT-induced production of primary saliva in the acini causes the intracellular pH changes in the ducts. Consequently, intracellular pH measurements in ducts are also useful to characterise transport processes in the acini. The Na+-K+-2Cl- cotransport and/or the Cl--HCO3- exchange combined with the Na+ H+ exchange (NHE) were responsible for the NaCl uptake at the basolateral membrane in the peripheral cells of the acini during production of primary saliva. The activity of these transporters was regulated by the CO2/HCO3--availability and was Ca2+-dependent. The activity of the basolateral Na+-K+-ATPase, but not of the apical vacuolar-type proton pump (V-H+-ATPase) in the duct cells was necessary for the strong intracellular acidification in the ducts with acini. Thus, the Na+-K+-ATPase seems to energise the saliva modification in the ducts. In ducts with acini, the V-H+-ATPase and Na+-dependent transporters (e.g. NHE) were responsible for the pH-recovery after a DA- or NH4Cl-induced intracellular acidification in the duct cells. In the regulation of the intracellular resting pH these transporters played a minor role. In addition, DA induced an increase in the intracellular Na+ concentration, followed by an increase in the intracellular Ca2+ concentration in duct cells with acini, but never in duct cells without acini. The Na+ elevation was probably the result of the activity of apical Na+ channels. The DA-induced Na+ elevation and a depolarisation of the basolateral membrane of the duct cells reversed a Na+-Ca2+ exchange activity into the reverse mode causing a graded Ca2+ elevation in duct cells. The Ca2+ elevation is probably involved in the regulation of the Na+ reabsorption during saliva modification. Transepithelial fluid transport in isolated ducts was detected with a fluorescent microscopical method. Already unstimulated isolated ducts reabsorbed fluid from the duct lumen to the bath side. Perhaps unstimulated acini possess a basic secretion rate and this primary saliva is than reabsorbed in the ducts. The fluid reabsorption was ATP-dependent, but the ATP-consuming transport mechanism could not be identified. Neither the basolateral Na+-K+-ATPase, nor the apical V-H+-ATPase were involved in fluid reabsorption. This work extends our knowledge about the complex function of insect salivary glands and about the cellular action of biogenic amines in insects. Additionally, it indicates lots of similarities between the functions of salivary glands in vertebrates and invertebrates. KW - Speicheldrüse KW - Amerikanische Schabe KW - Insekten KW - Speichel KW - epithelialer Transport KW - ratiometric imaging KW - Signalkaskaden KW - biogene Amine KW - Dopamin KW - Serotonin KW - salivary glands KW - epithelial transport KW - biogenic amines KW - dopamine KW - serotonin KW - cockroach KW - insects Y1 - 2006 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-9422 ER -