TY - JOUR A1 - Troppmann, Britta A1 - Balfanz, Sabine A1 - Krach, Christian A1 - Baumann, Arnd A1 - Blenau, Wolfgang T1 - Characterization of an Invertebrate-Type Dopamine Receptor of the American Cockroach, Periplaneta americana JF - International journal of molecular sciences N2 - We have isolated a cDNA coding for a putative invertebrate-type dopamine receptor (Peadop2) from P. americana brain by using a PCR-based strategy. The mRNA is present in samples from brain and salivary glands. We analyzed the distribution of the PeaDOP2 receptor protein with specific affinity-purified polyclonal antibodies. On Western blots, PeaDOP2 was detected in protein samples from brain, subesophageal ganglion, thoracic ganglia, and salivary glands. In immunocytochemical experiments, we detected PeaDOP2 in neurons with their somata being located at the anterior edge of the medulla bilaterally innervating the optic lobes and projecting to the ventro-lateral protocerebrum. In order to determine the functional and pharmacological properties of the cloned receptor, we generated a cell line constitutively expressing PeaDOP2. Activation of PeaDOP2-expressing cells with dopamine induced an increase in intracellular cAMP. In contrast, a C-terminally truncated splice variant of this receptor did not exhibit any functional property by itself. The molecular and pharmacological characterization of the first dopamine receptor from P. americana provides the basis for forthcoming studies focusing on the significance of the dopaminergic system in cockroach behavior and physiology. KW - G-protein-coupled receptor KW - dopamine KW - insect KW - cellular signaling KW - salivary gland KW - biogenic amine Y1 - 2014 U6 - https://doi.org/10.3390/ijms15010629 SN - 1422-0067 VL - 15 IS - 1 SP - 629 EP - 653 PB - MDPI CY - Basel ER - 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 - JOUR A1 - Gleich, Tobias A1 - Spitta, Gianna A1 - Butler, Oisin A1 - Zacharias, Kristin A1 - Aydin, Semiha A1 - Sebold, Miriam Hannah A1 - Garbusow, Maria A1 - Rapp, Michael Armin A1 - Schubert, Florian A1 - Buchert, Ralph A1 - Heinz, Andreas A1 - Gallinat, Jürgen T1 - Dopamine D2/3 receptor availability in alcohol use disorder and individuals at high risk BT - towards a dimensional approach JF - Addiction Biology N2 - Alcohol use disorder (AUD) is the most common substance use disorder worldwide. Although dopamine-related findings were often observed in AUD, associated neurobiological mechanisms are still poorly understood. Therefore, in the present study, we investigate D2/3 receptor availability in healthy participants, participants at high risk (HR) to develop addiction (not diagnosed with AUD), and AUD patients in a detoxified stage, applying F-18-fallypride positron emission tomography (F-18-PET). Specifically, D2/3 receptor availability was investigated in (1) 19 low-risk (LR) controls, (2) 19 HR participants, and (3) 20 AUD patients after alcohol detoxification. Quality and severity of addiction were assessed with clinical questionnaires and (neuro)psychological tests. PET data were corrected for age of participants and smoking status. In the dorsal striatum, we observed significant reductions of D2/3 receptor availability in AUD patients compared with LR participants. Further, receptor availability in HR participants was observed to be intermediate between LR and AUD groups (linearly decreasing). Still, in direct comparison, no group difference was observed between LR and HR groups or between HR and AUD groups. Further, the score of the Alcohol Dependence Scale (ADS) was inversely correlated with D2/3 receptor availability in the combined sample. Thus, in line with a dimensional approach, striatal D2/3 receptor availability showed a linear decrease from LR participants to HR participants to AUD patients, which was paralleled by clinical measures. Our study shows that a core neurobiological feature in AUD seems to be detectable in an early, subclinical state, allowing more individualized alcohol prevention programs in the future. KW - alcohol KW - D2/3 receptors KW - dependence KW - dopamine KW - high risk KW - PET Y1 - 2020 U6 - https://doi.org/10.1111/adb.12915 SN - 1369-1600 VL - 26 IS - 2 SP - 1 EP - 10 PB - Wiley-Blackwell CY - Hoboken ER - TY - THES A1 - Galetzka, Cedric T1 - Reward and prediction errors in Bayesian sensorimotor control N2 - Midbrain dopamine neurons invigorate responses by signaling opportunity costs (tonic dopamine) and promote associative learning by encoding a reward prediction error signal (phasic dopamine). Recent studies on Bayesian sensorimotor control have implicated midbrain dopamine concentration in the integration of prior knowledge and current sensory information. The present behavioral study addressed the contributions of tonic and phasic dopamine in a Bayesian decision-making task by alternating reward magnitude and inferring reward prediction errors. Twenty-four participants were asked to indicate the position of a hidden target stimulus under varying prior and likelihood uncertainty. Trial-by-trial rewards were allocated based on performance and two different reward maxima. Overall, participants’ behavior agreed with Bayesian decision theory, but indicated excessive reliance on likelihood information. These results thus oppose accounts of statistically optimal integration in sensorimotor control, and suggest that the sensorimotor system is subject to additional decision heuristics. Moreover, higher reward magnitude was not observed to induce enhanced response vigor, and was associated with less Bayes-like integration. In addition, the weighting of prior knowledge and current sensory information proceeded independently of reward prediction errors. Taken together, these findings suggest that the process of combining prior and likelihood uncertainties in sensorimotor control is largely robust to variations in reward. N2 - Inwieweit prägen Belohnungen die Integration von vorherigem Wissen und sensorischen Informationen im Kontext der Bayesianischen Entscheidungstheorie? Untersuchungen mit Parkinson-Patienten haben gezeigt, dass die Dopamin-Verfügbarkeit in den Basalganglien Integrationsprozesse in der Sensomotorik beeinflussen. Dopaminerge Neuronen schütten Dopamin tonisch und phasisch aus, wobei diese Modi verschiedenen Funktionen unterliegen, wie dem Signalisieren von Opportunitätskosten oder der Unterstützung assoziativen Lernens. Die Konzentration tonisch freigesetzten Dopamins richtet sich nach Belohnungsgrößen, wogegen phasische Dopamin-Komponenten durch Fehler in der Belohnungserwartung hervorgerufen werden. Die Bedeutung dieser Variablen in sensomotorischem Lernen ist jedoch größtenteils unerforscht. In der vorliegenden Verhaltensstudie wurden vierundzwanzig gesunde Teilnehmer gebeten, eine sensomotorische Schätzaufgabe durchzuführen, in der Belohnungsgrößen manipuliert und Belohnungserwartungsfehler abgeleitet wurden. Es wurde vermutet, dass positive Abweichungen in der Belohnungsvorhersage zu erhöhter Gewichtung von sensorischen Informationen durch den Influx phasischen Dopamins führen. Höhere Belohnungsgrößen sollten dagegen aufgrund vermehrter Opportunitätskosten mit beschleunigten Reaktionen verbunden sein. Das Verhalten der Teilnehmer hat gezeigt, dass aktuelle und a priori Informationen größtenteils unabhängig von Belohnungsgrößen und Belohungserwartungsfehlern integriert werden. Dieses Ergebnis deutet darauf hin, dass “Prior” und “Likelihood” unabhängig von belohnungsrelevanten Prozessen repräsentiert werden, welche in Zusammenhang mit der Dopamin-Konzentration in den Basalganglien stehen. Darüber hinaus entsprachen die Resultate lediglich qualitativ der Bayesianischen Entscheidungstheorie und widersprechen somit früheren Berichten von statistisch-optimaler Integration. Da sensorische Informationen über alle Bedingungen hinweg übermäßig hoch gewichtet wurden, legt diese Studie nahe, dass das sensomotorische System zusätzlichen systematischen Urteilsverzerrungen unterliegt. KW - Bayesian decision theory KW - reward prediction error KW - sensorimotor control KW - prior-likelihood integration KW - dopamine KW - Belohnungserwartungsfehler KW - Belohnungsgrößen KW - Bayesianische Entscheidungstheorie KW - sensomotorische Integration KW - Dopamin Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-503507 ER - TY - JOUR A1 - Deserno, Lorenz A1 - Beck, Anne A1 - Huys, Quentin J. M. A1 - Lorenz, Robert C. A1 - Buchert, Ralph A1 - Buchholz, Hans-Georg A1 - Plotkin, Michail A1 - Kumakara, Yoshitaka A1 - Cumming, Paul A1 - Heinze, Hans-Jochen A1 - Grace, Anthony A. A1 - Rapp, Michael Armin A1 - Schlagenhauf, Florian A1 - Heinz, Andreas T1 - Chronic alcohol intake abolishes the relationship between dopamine synthesis capacity and learning signals in the ventral striatum JF - European journal of neuroscience N2 - Drugs of abuse elicit dopamine release in the ventral striatum, possibly biasing dopamine-driven reinforcement learning towards drug-related reward at the expense of non-drug-related reward. Indeed, in alcohol-dependent patients, reactivity in dopaminergic target areas is shifted from non-drug-related stimuli towards drug-related stimuli. Such hijacked' dopamine signals may impair flexible learning from non-drug-related rewards, and thus promote craving for the drug of abuse. Here, we used functional magnetic resonance imaging to measure ventral striatal activation by reward prediction errors (RPEs) during a probabilistic reversal learning task in recently detoxified alcohol-dependent patients and healthy controls (N=27). All participants also underwent 6-[F-18]fluoro-DOPA positron emission tomography to assess ventral striatal dopamine synthesis capacity. Neither ventral striatal activation by RPEs nor striatal dopamine synthesis capacity differed between groups. However, ventral striatal coding of RPEs correlated inversely with craving in patients. Furthermore, we found a negative correlation between ventral striatal coding of RPEs and dopamine synthesis capacity in healthy controls, but not in alcohol-dependent patients. Moderator analyses showed that the magnitude of the association between dopamine synthesis capacity and RPE coding depended on the amount of chronic, habitual alcohol intake. Despite the relatively small sample size, a power analysis supports the reported results. Using a multimodal imaging approach, this study suggests that dopaminergic modulation of neural learning signals is disrupted in alcohol dependence in proportion to long-term alcohol intake of patients. Alcohol intake may perpetuate itself by interfering with dopaminergic modulation of neural learning signals in the ventral striatum, thus increasing craving for habitual drug intake. KW - alcohol addiction KW - dopamine KW - fMRI KW - PET KW - prediction error Y1 - 2015 U6 - https://doi.org/10.1111/ejn.12802 SN - 0953-816X SN - 1460-9568 VL - 41 IS - 4 SP - 477 EP - 486 PB - Wiley-Blackwell CY - Hoboken ER -