Yale Researchers Stop Sugar-Craving in Fruit Flies

Scientists Stop Sugar Craving

(A) Drosophila head. The box indicates the region of the proboscis containing the labral sense organ (LSO, shaded) of the pharynx. (B) The pharyngeal region containing the LSO. The position of sensillum 7 is indicated. (C) IR60b-GAL4; UAS-GFP shows expression in a single pair of neurons that project dendrites (d) to the pore of sensillum 7, whose position is indicated. (cb), cell body. To maximize the fidelity of the driver, GAL4 was placed between sequences lying 5’ and 3’ to IR60b. Scale bar = 5 μm. Green color represents UAS-GFP fluorescence, visualized with a 488 nm laser. Magenta color represents cuticular autofluorescence, visualized with a 514 nm laser. (D) IR60b is the only member of the IR20a clade that shows a significantly negative Direction of Selection (DoS) signature.

Working with fruit flies, researchers from Yale University have discovered ways to blunt the craving for sugar.

A single pair of neurons in the throat of Drosophila act as a brake on the consumption of sucrose, according to a new study published in April in the journal eLife.

“This was very surprising because most sugar-sensing taste cells promote eating, but these are doing just the opposite,” said John Carlson, the Eugene Higgins Professor of Molecular, Cellular & Developmental Biology and senior author of the study.

The control of fundamental processes such as eating, Carlson points out, is often very similar in Drosophila and humans, which are in the midst of a rapidly growing global obesity epidemic.

The Yale team — including first author Ryan M. Joseph, Jennifer S. Sun, and Edric Tam — investigated a Drosophila gene of unknown function. They found that the gene, IR60b, was expressed only in a single pair of nerve cells found in the pharynx of flies. When either this gene or these nerve cells were disabled, flies ate more sucrose. Alternately, when the nerve cells were activated by red light via optogenetics, the flies ate less.

Carlson noted that this genetic brake on sucrose consumption was slow to activate, suggesting that mechanisms to induce feeding are activated quickly and are then inhibited by IR60b.

The scientists now plan to see if mammals use the same system to control the amount of sugar they consume.

The research was funded by the National Institutes of Health.

Reference: “A receptor and neuron that activate a circuit limiting sucrose consumption” Ryan M Joseph, Jennifer S Sun, Edric Tam and John R Carlson, 23 March 2017, eLife.
DOI: 10.7554/eLife.24992

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