Dopaminergic mushroom body neurons in Drosophila: Flexibility of neuron identity in a model organism?. (April 2022)

• Record Type: Journal Article
• Authors: Dvořáček, Jiří; Bednářová, Andrea; Krishnan, Natraj; Kodrík, Dalibor
• Is Part Of: Neuroscience and biobehavioral reviews. Volume 135(2022)
• Publication Date: 2022-04
• Subjects: Dopaminergic function -- Brain reward system -- Co-transmission -- Neurotransmitter switching -- Insect brain -- Neural plasticity -- Universality of neural function; Psychophysiology -- Periodicals; Human behavior -- Periodicals; Animal behavior -- Periodicals; Neurology -- Periodicals; Behavior -- Periodicals; Ethology -- Periodicals; Neurology -- Periodicals; Psychophysiologie -- Périodiques; Comportement humain -- Périodiques; Animaux -- Mœurs et comportement -- Périodiques; Neurologie -- Périodiques; Animal behavior; Human behavior; Neurology; Psychophysiology; Periodicals; Electronic journals; 573.8
• DOI: 10.1016/j.neubiorev.2022.104570
• Languages: English
• ISSNs: 0149-7634

Abstract

Abstract: In classical neuroscience, Dale´s principle postulates that neuronal identity is conferred by the specific neurotransmitter that it releases. However, the brain might be more tractable to specific situations regardless of specific specialisation which may contradict this principle. Hence, this constrained approach of how we perceive and study the nervous system must be revisited and revised, specifically by studying the dopaminergic system. We presume a relatively flexible change in the dopaminergic system due to neuronal activity or environmental changes. While the parallel between the reward system of mammals and insects is generally well accepted, herein, we extend the idea that the insect nervous system might also possess incredible plasticity, similar to the mammalian system. In this review, we critically evaluate the available information about the reward system in vertebrates and invertebrates, emphasising the dopaminergic neuronal plasticity, a challenge to the classical Dale's principle. Thus, neurotransmitter switching significantly disrupts the static idea of neural network organisation and suggests greater possibilities for a dynamic response to the current life context of organisms. Highlights: There is an obvious parallel relationship between the function of DAN in the reward systems of mammals and Drosophila, although the complexity of the function is probably different. There is also evidence that the dopamine signaling pathway has similar biochemical and molecular elements, and shares similar functional principles in all animals. Co-transmission in dopaminergic neurons in mammalian VTA is documented as functionally necessary – dual neurons in the VTA form a specific subpopulation. In Drosophila, there is an evidence of co-transmission of DAN in MB (with neuropeptides or fast-acting neurotransmitters). However, a clear subpopulation of these dual neurons has not yet been identified, although there is evidence of a possible relationship between the co-transmission and output to specific MBONs. The number of DANs, specifically, the number of cells with a dopamine phenotype, is activity-dependent in certain brain parts of certain vertebrates under certain conditions and may vary according to environmental conditions. In Drosophila, the possibilities of neurotransmitter switching are only indicated; studies focused on a possible switch of neurotransmitters in DAN will have to be conducted. DANs have a solid capacity to contradict Dale´s principle. The question arises if there is a neuron at all with one transmitter only in all circumstances that always resists environmental pressure and network activity to express genes other than those expressed during individual development. The possible different capacity of mammalian and insect DAN (in our case Drosophila) to transmitter plasticity may be the cause (or consequence) of a different function of the reward system.