About this Research Topic
Until recently, tyramine was considered to be the precursor of octopamine only, without playing any other major role in insects. The late discovery of the action of tyramine and its localization indicate that tyramine has its own functions and source, independent of that of octopamine. In fact, some studies suggest that tyramine and octopamine may have opposite functions. Also, both, tyramine and octopamine, can act like hormones. Both amines trigger intracellular signaling pathways by binding with various affinities to octopamine/tyramine receptors which are known to be G-protein coupled receptors. The N-terminus domain binds the ligand, e.g. OA, whereas the C-terminus and intracellular domains bind intracellular second messengers. These receptors are categorized into alpha-adrenergic-like receptors (OA1-alpha type) and beta-adrenergic receptor type (OA2-beta type). Activation of OA1 receptors increases the intracellular Ca2+ concentration, whereas activation of OA2 receptors stimulates adenylate cyclase, thereby increasing the concentration of adenosine 3’,5’-cyclic monophosphate (cAMP).
As of today, the mechanism of release of biogenic amines is unknown. Do the neurons that express octopamine release octopamine and tyramine at the same time? Could it be possible that tyramine found in the brain is of non-neuronal origin? One of the aims of this field of research is to understand the action of amines in different neuronal and non-neuronal circuits using a variety of techniques including live imaging, microscopy, electrophysiology and molecular biology. In insects, antennal lobes and mushroom bodies are well-studied circuits for neural plasticity where the octopaminergic neurons are critical for appetitive learning. However, very little is known about how the various biogenic amine receptors are integrated into neural networks to potentially drive associations. In contrast to OA1 receptors in the antennal lobe and mushroom bodies, little is known about OA2 type and Tyr1 receptors role in this network. We would like to elucidate in detail the “orchestrational” function of biogenic amines as their role in the periphery of modulating synaptic transmission and catabolic pathways is accompanied by specific actions within the nervous system, for example, motor circuits.
Thus, for this research topic we encourage scientists from different disciplines to participate in the study covered above subjects involving different types of biogenic amines and their receptors, including but not limited to tyramine, octopamine, serotonin, histamine, and dopamine.
Subjects covered in our research topic include:
-Historical overview of discovery biogenic amine and its role in behavior
-Neuroanatomy of biogenic amine expression
-Functional dissection of neuronal circuitry modulated by biogenic amines
-Computational modeling of modulation by biogenic amines at the cellular and whole organism levels
- Molecular mechanism of the biogenic amine regulation of Ca2+ and cAMP signal systems
Keywords: biogenic amines, octopamine, tyramine, invertebrate, G-protein coupled receptors (GPCR), neural circuits, olfactory learning and memory, neuromodulation, insect brain, antennal lobe, mushroom bodies
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