Mapping of serotonin, dopamine, and histamine in relation to different clock neurons in the brain ofDrosophila

Department of Zoology, Stockholm University, SE-10691, Sweden.
The Journal of Comparative Neurology (Impact Factor: 3.51). 01/2006; 494(2):314-30. DOI: 10.1002/cne.20807
Source: PubMed

ABSTRACT Several sets of clock neurons cooperate to generate circadian activity rhythms in Drosophila melanogaster. To extend the knowledge on neurotransmitters in the clock circuitry, we analyzed the distribution of some biogenic amines in relation to identified clock neurons. This was accomplished by employing clock neuron-specific GAL4 lines driving green fluorescent protein (GFP) expression, combined with immunocytochemistry with antisera against serotonin, histamine, and tyrosine hydroxylase (for dopamine). In the larval and adult brain, serotonin-immunoreactive (-IR) neuron processes are in close proximity of both the dendrites and the dorsal terminals of the major clock neurons, the s-LN(v)s. Additionally, the terminals of the l-LN(v) clock neurons and serotonergic processes converge in the distal medulla. No histamine (HA)-IR processes contact the s-LN(v)s in the larval brain, but possibly impinge on the dorsal clock neurons, DN2. In the adult brain, HA-IR axons of the extraocular eyelet photoreceptors terminate on the dendritic branches of the LN(v)s. A few tyrosine hydroxylase (TH)-IR processes were seen close to the dorsal terminals of the s-LN(v)s, but not their dendrites, in the larval and adult brain. TH-IR processes also converge with the distal medulla branches of the l-LN(v)s in adults. None of the monoamines was detectable in the different clock neurons. By using an imaging system to monitor intracellular Ca(2+) levels in dissociated GFP-labeled larval s-LN(v)s, loaded with Fura-2, we demonstrated that application of serotonin induced dose-dependent decreases in Ca(2+). Thus, serotonergic neurons form functional inputs on the s-LN(v)s in the larval brain and possibly also in adults.

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    • "Thus, the l-LN v neurons are anatomically well suited to modulate the activity of many neurons. In addition, their arborisations overlap with those of monaminergic neurons (Hamasaka and Nässel, 2006). Several studies show that they indeed receive dopaminergic, octopaminergic and GABAergic input and that they control the flies' arousal and sleep (Agosto et al., 2008; Parisky et al., 2008; Kula-Eversole et al., 2010; Shang et al., 2011). "
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    ABSTRACT: GABAergic signalling is important for normal sleep in humans and flies. Here we advance the current understanding of GABAergic modulation of daily sleep patterns by focusing on the role of slow metabotropic GABAB receptors in the fruit fly Drosophila melanogaster. We asked whether GABAB-R2 receptors are regulatory elements in sleep regulation in addition to the already identified fast ionotropic Rdl GABAA receptors. By immunocytochemical and reporter-based techniques we show that the pigment dispersing factor (PDF)-positive ventrolateral clock neurons (LNv) express GABAB-R2 receptors. Downregulation of GABAB-R2 receptors in the large PDF neurons (l-LNv) by RNAi reduced sleep maintenance in the second half of the night, whereas sleep latency at the beginning of the night that was previously shown to depend on ionotropic Rdl GABAA receptors remained unaltered. Our results confirm the role of the l-LNv neurons as an important part of the sleep circuit in D. melanogaster and also identify the GABAB-R2 receptors as the thus far missing component in GABA-signalling that is essential for sleep maintenance. Despite the significant effects on sleep, we did not observe any changes in circadian behaviour in flies with downregulated GABAB-R2 receptors, indicating that the regulation of sleep maintenance via l-LNv neurons is independent of their function in the circadian clock circuit.
    Journal of Experimental Biology 10/2013; 216(Pt 20):3837-43. DOI:10.1242/jeb.085563 · 3.00 Impact Factor
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    • "N/A: no information available about neurotransmitter and neuropeptides received or released by that particular cluster. Not included in the table but worth noting is the information relevant to neurotransmission in the larval circadian clusters, which includes the substances PDF (Renn et al., 1999), ACh (Wegener et al., 2004), GABA (Hamasaka et al., 2005), Serotonin (Hamasaka and Nassel, 2006), Glutamate (Hamasaka et al., 2007) and sNPF (Johard et al., 2009). "
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    ABSTRACT: Over the years it has become crystal clear that a variety of processes encode time of day information, ranging from gene expression, protein stability, or subcellular localization of key proteins, to the fine tuning of network properties and modulation of input signals, ultimately ensuring that physiology and behavior are properly synchronized to a changing environment. The purpose of this review is to put forward examples (as opposed to generate a comprehensive revision of all the available literature) in which the circadian system displays a remarkable degree of plasticity, from cell autonomous to circuit-based levels. In the literature, the term circadian plasticity has been used to refer to different concepts. The obvious one, the more literally, refers to any change that follows a circadian (circa=around, diem=day) pattern, i.e. a daily change of a given parameter. The discovery of daily remodeling of neuronal structures will be referred herein as structural circadian plasticity, and represents an additional and novel phenomenon modified daily. Finally, any plasticity that has to do with a circadian parameter would represent a type of circadian plasticity; as an example, adjustments that allow organisms to adapt their daily behavior to the annual changes in photoperiod is a form of circadian plasticity at a higher organizational level, which is an emergent property of the whole circadian system. Throughout this work we will revisit these types of changes by reviewing recent literature delving around circadian control of clock outputs, from the most immediate ones within pacemaker neurons to the circadian modulation of rest-activity cycles.
    Neuroscience 05/2013; 247. DOI:10.1016/j.neuroscience.2013.05.036 · 3.33 Impact Factor
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    • "For both mammals and flies, the control of circadian rhythmicity is complex and may involve multiple aminergic systems including 5-HT and DA (Meijer and Groos 1988; Morin and Blanchard 1991; Yuan et al. 2005; Hamasaka and Nässel 2006; Nässel and Homberg 2006; Suh and Jackson 2007; Crocker et al. 2010; Hirsh et al. 2010; Kula-Eversole et al. 2010; Gravotta et al. 2011). However, it is unknown whether the different aminergic systems function independently, cooperatively , or in a complementary manner in the regulation of rhythmicity. "
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    ABSTRACT: To investigate the regulation of Drosophila melanogaster behavior by biogenic amines, we have exploited the broad requirement of the vesicular monoamine transporter (VMAT) for the vesicular storage and exocytotic release of all monoamine neurotransmitters. We used the Drosophila VMAT (dVMAT) null mutant to globally ablate exocytotic amine release, and then restored DVMAT activity in either individual or multiple aminergic systems using transgenic rescue techniques. We find that larval survival, larval locomotion, and female fertility rely predominantly on octopaminergic circuits with little apparent input from the vesicular release of serotonin or dopamine. In contrast, male courtship and fertility can be rescued by expressing DVMAT in octopaminergic or dopaminergic neurons, suggesting potentially redundant circuits. Rescue of major aspects of adult locomotion and startle behavior required octopamine, but a complementary role was observed for serotonin. Interestingly, adult circadian behavior could not be rescued by expression of DVMAT in a single subtype of aminergic neurons, but required at least two systems, suggesting the possibility of unexpected cooperative interactions. Further experiments using this model will help determine how multiple aminergic systems may contribute to the regulation of other behaviors. Our data also highlight potential differences between behaviors regulated by standard exocytotic release versus other mechanisms.
    Genetics 10/2012; 193(1). DOI:10.1534/genetics.112.142042 · 4.87 Impact Factor
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