In a screen using a thermogenetic activator targeted to different subsets of neurons in the adult brain, a group of appetite-controlling neurons was identified. Manipulating the activity of these neurons induces bidirectional changes in feeding motivation. The neurons were designated "Taotie" neurons after a gluttonous creature from Chinese mythology. In satiated flies, activation of Taotie neurons evokes vigorous feeding; in hungry flies, inhibition of Taotie neurons strongly reduces food intake. Long-term stimulation of Taotie neurons results in flies with highly obese phenotypes, but the effect is reversible: all of the obese phenotypes revert back to their normal states within 4 days of no activation.
Since the neurons act bidirectionally, this system may be useful as a fly model of anorexia (loss of appetite), as well.
Taotie neurons appear to act upstream of the insulin system. Activation of Taotie neurons in satiated flies results in accumulation of insulin signals in the insulin producing cells (IPC) cells, mimicking the conditions of starvation. Inactivation of Taotie neurons reduces the accumulation of insulin in starved flies. Thus, modulating the activity of Taotie neurons forces changes in the neuroendocrine status, even if these changes are in contradiction to the true/actual physiological state of the animal.
[updated Jul. 2019 by FlyBase; FBrf0222196]
Obesity is an abnormal accumulation of body fat, usually 20% or more over an individual's ideal body weight. Obesity is associated with increased risk of illness, disability, and death. (http://medical-dictionary.thefreedictionary.com/obesity).
The development of obesity is recognized as having both genetic and environmental components (https://www.sciencelearn.org.nz/resources/203-obesity-genetic-or-environmental).
