In a novel study conducted in fruit flies, researchers have identified two groups of neurons that control obesity.
Lead researcher Kai Zinn, professor of biology at California Institute of Technology (Caltech), suggests that the two groups of neurons have the ability to sense and manipulate the fly's fat stores in much the same way, as do neurons in the mammalian brain.
By manipulating neural activity in fruit fly brains using transgenic techniques, the researchers found that, "just as in mammals, fly fat-store levels are measured and controlled by specific neurons in the brain," said Caltech postdoctoral scholar Bader Al-Anzi, the Neuron paper's first author.
"Silencing these neurons created obese flies, while overactivating them produced lean flies," he added.
Mammalian brains are given information about the body's fat stores by hormones such as leptin and insulin, and respond to that information by inducing changes in food intake and metabolism to maintain a constant body weight.
The researchers found that similar behavioural and metabolic changes occurred in the fruit flies, though the changes depended on which of the two sets of newly identified neurons was silenced.
For instance, silencing one group of neurons led to an increase in food intake, a decrease in metabolism, and an increase in the synthesis of fatty acids (the building blocks of fat).
Silencing the other group led to a similar decrease in metabolism and increase in fatty-acid synthesis, as well as to a defect in the flies' ability to utilize their fat stores.
The next step is to "see exactly how neurons regulate fat storage, and how the two different groups of neurons identified in this study work," said Zinn.
"They clearly regulate fat storage using different mechanisms," Zinn added.
The study appears in journal Neuron.