Tyramine synthesis, vesicular packaging, and the SNARE complex function coordinately in astrocytes to regulate Drosophila alcohol sedation

Vesicular monoamine transporter (VMAT) regional expression and roles in pathological conditions

Vesicular monoamine transporters (VMATs) are key regulators of neurotransmitter release responsible for controlling numerous physiological, cognitive, emotional, and behavioral functions. They represent important therapeutic targets for numerous pathological conditions. There are two isoforms of VMAT transporter proteins that function as secondary active transporters into the vesicle for storage and release via exocytosis: VMAT1 (SLC18A1) and VMAT2 (SLC18A2) which differ in their function, quantity, and regional expression. VMAT2 has gained considerable interest as a therapeutic target and diagnostic marker. Inhibitors of VMAT2 have been used as an effective therapy for a range of pathological conditions. Additionally, the functionality and phenotypic classification of classical and nonclassical catecholaminergic neurons are identified by the presence of VMAT2 in catecholaminergic neurons. Dysregulation of VMAT2 is also implicated in many neuropsychiatric diseases. Despite the complex role of VMAT2, many aspects of its function remain unclear. Therefore, our aim is to expand our knowledge of the role of VMAT with a special focus on VMAT2 in different systems and cellular pathways which may potentially facilitate development of novel, more specific therapeutic targets. The current review provides a summary demonstrating the mechanism of action of VMAT, its functional role, and its contribution to disease progression and utilization as therapeutic targets.

A role for glia in cellular and systemic metabolism: insights from the fly

Excitability and synaptic transmission make neurons high-energy consumers. However, neurons do not store carbohydrates or lipids. Instead, they need support cells to fuel their metabolic demands. This role is assumed by glia, both in vertebrates and invertebrates. Many questions remain regarding the coupling between neuronal activity and energy demand on the one hand, and nutrient supply by glia on the other hand. Here, we review recent advances showing that fly glia, similar to their role in vertebrates, fuel neurons in times of high energetic demand, such as during memory formation and long-term storage. Vertebrate glia also play a role in the modulation of neurons, their communication, and behavior, including food search and feeding. We discuss recent literature pointing to similar roles of fly glia in behavior and metabolism.

Identification of additional dye tracers for measuring solid food intake and food preference via consumption-excretion in Drosophila

The Drosophila model has become a leading platform for investigating mechanisms that drive feeding behavior and the effect of diet on physiological outputs. Several methods for tracking feeding behavior in flies have been developed. One method, consumption-excretion or Con-Ex, provides flies with media labeled with dye and then quantifies the amount of dye excreted into the vial as a measure of consumption. We previously found that Blue 1 and Orange 4 work well in Con-Ex and can be used as a dye pair in food preference studies. We have expanded our development of Con-Ex by identifying two additional dyes, Orange G and Yellow 10, that detect the anticipated effects of mating status, strain, starvation and nutrient concentration. Additionally, Orange G and Yellow 10 accumulate linearly in excretion products out to 48 h and the excreted volumes of these two dyes reflect the volumes consumed. Orange G also works with Blue 1 as a dye pair in food preference studies. Finally, consumption of Blue 1, Orange 4, Orange G or Yellow 10 does not affect ethanol sedation or rapid tolerance to ethanol. Our findings establish that Orange G and Yellow 10, like Blue 1 and Orange 4, are suitable for use in Con-Ex.