Their discovery of the neural changes that control odor-driven food searches in flies, which they detail in a paper in the April 1 issue of the journal Cell, could provide a new way to potentially regulate human appetite.
By developing drugs to enhance or minimize the activity of nerve-signaling chemicals called neuropeptides released during starvation to enhance the sense of smell, scientists may be able to decrease the propensity among obese individuals to overeat when encountering delectable food odors, if similar molecular mechanisms exist in humans. They could also increase the appetites among the infirm, elderly and others who may have problems eating enough. The method could even be used to improve the growth of farmed animals or to reduce feed waste.
“Olfaction makes important contributions to the perception of food quality and profoundly influences our dietary choices,” said Jing Wang, an associate professor of biology at UC San Diego who headed the research effort. His team identified a neuropeptide and a receptor neuron controlling the olfactory behavior in the fly that could be targeted by drugs to effect changes in appetite that are normally regulated by an organism’s insulin levels, which changes radically when organisms are satiated or starved.
“Our studies in Drosophila address an important question—how starvation modulates olfactory processing,” he added. “We were surprised to find that starvation modulation of smell happens at the periphery, because most of the literature on feeding regulations is about the function of the hypothalamus. There are hints to suggest that this kind of starvation modulation in the peripheral olfactory system is present in vertebrate systems as well.”
While scientists had previously identified similar neuropeptides that control feeding behavior in vertebrates, not much was known until now about how these molecules control olfaction or an organism’s behavior. Researchers had previously found that the injection into the hypothalamus of insulin, the hormone that regulates blood glucose levels, reduces food intake in rodents, for example, but how insulin affects olfactory circuits in a way that altered an organism’s behavior was not well understood.
Wang and his team of UCSD biologists—Cory Root, Kang Ko and Amir Jafari—believed that by looking at the molecular mechanisms that enable fruit flies to improve their search for food when their insulin levels were low following a period of starvation the scientists would obtain a better understanding of this process. They used a computerized system to monitor over time the position of starved or well-fed flies as the flies circled around a droplet of apple cider vinegar, which served as a delectable food source.
“During the 10 min observation period,” the researchers wrote in their paper, “starved flies spend most of the time walking near the food source, whereas fed flies wander in the entire arena with a preference for the perimeter.”
The researchers found that surgical removal of the antennae used by the flies to sense odor destroyed the propensity of starved flies to hone in on the food source as did genetically suppressing the production of short neuropeptide F receptors, which the scientists found, increases in response to starvation or a drop in insulin levels. Using two-photon microscopy, a state-of-the-art imaging system, the researchers found starvation-dependent changes of olfactory response in specific neurons.
“The notion that starvation modulation at the peripheral olfactory system is linked to insulin signaling has potential implications for the therapeutic intervention of the seemingly unstoppable obesity epidemic trend in a large percentage of the population,” said Wang.
He said his team’s study has identified the insulin receptor, PI3K, and the short neuropeptide F receptor, which is also modulated by insulin levels, as potential molecular targets for controlling appetite in humans and other vertebrates. However, he added that more research is needed to know whether and to what extent insulin levels control olfactory sensitivity in human.
“Learning how olfactory neural circuits impact dietary choices is relevant towards better understanding factors that contribute to obesity and eating disorders,” he added.
Based on their findings, the UCSD biologists have filed a patent application on their discovery, contending that blocking PI3K, a signaling molecule of the insulin receptor, could improve appetites in the infirm and elderly and that the intranasal delivery of insulin could decrease appetite in obese individuals. They also contend in their patent application that suppressing PI3K will increase feeding in farmed animals and reduce feed waste.
The researchers’ work was funded by the National Institute on Deafness and Other Communication Disorders.
Kim McDonald | Newswise Science News
Researchers uncover protein-based “cancer signature”
05.12.2016 | Universität Basel
The Nagoya Protocol Creates Disadvantages for Many Countries when Applied to Microorganisms
05.12.2016 | Leibniz-Institut DSMZ-Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water
In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
05.12.2016 | Power and Electrical Engineering
05.12.2016 | Materials Sciences
05.12.2016 | Power and Electrical Engineering