AsianScientist (Dec. 21, 2016) – Researchers from the Institute of Biophysics of the Chinese Academy of Sciences have discovered a cluster of neurons in the brains of flies that affect appetite and control body weight. Their study was published in Nature Communications.
A mismatch between the physiological requirement for food and the drive to eat is increasingly responsible for obesity, but the process underlying the decision on when to eat and how much to eat is largely unknown. The complexity of feeding behavior and closely intertwined neural-physiological processes makes the task of understanding the neural control of feeding behavior difficult.
To understand the neural circuits that control appetite, a team of researchers led by Dr. Zhu Yan used neurogenetics, optogenetics, and behavioral approaches to identify a group of appetite-enhancing neurons in fruit flies. Artificial activation of these neurons—named ‘Taotie’ neurons after an ancient Chinese ogre known for its insatiable appetite—rapidly increases the appetite of otherwise normal animals.
Interestingly, long-term activation of Taotie neurons in flies increased their body weight and fat storage. The degree of ‘obesity’ was directly correlated with the strength of Taotie neuron activation, suggesting that Taotie neurons are part of neural circuit that determines the body energy homeostasis.
The researchers further found that the activity in a cluster of Taotie neurons in the neuroendocrine region of brain correlates well with the hunger and satiety states of flies, suggesting that these neurons can reflect the physiological states of the animals.
In mammals, hypothalamic brain centers receive information about the physiological status through hormonal signals such as leptin, insulin and ghrelin. These centers also control feeding behavior to maintain homeostasis. Previously, it was unknown whether the tiny brain of the fruit fly possesses feeding centers like mammalian brains do. This is the first study to reveal that fruit fly brains also have a master center of feeding that can both represent physiological states and coordinate feeding behavior.
By providing a conceptual framework for studying hunger in flies, the authors hope that Taotie neurons will inspire a new wave of studies on the neural mechanisms of homeostasis and shed light on the root of eating disorders, such as anorexia nervosa and bulimia nervosa.
The article can be found at: Zhan et al. (2016) Taotie Neurons Regulate Appetite in Drosophila.
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Source: Chinese Academy of Sciences; Photo: Pixabay.
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