Neurons responsible for overeating discovered
Now, two independent studies published in Cell have identified neurons in the hypothalamus that are responsible for overeating, particularly sucrose consumption.
Using similar techniques as researchers in the thirst experiment, a team led by neuroscientist Garret Stuber of the University of North Carolina, Chapel Hill, used optogenetics to activate specific neurons called GABAergic neurons, which led mice to eat more frequently. When the neurons were inhibited, the mice were not motivated to eat in excess.
The second study, led by MIT neuroscientist Kay Tye, also used optogenetic techniques in mice to target GABAergic neurons in the lateral hypothalamus that link to the ventral tegmental area of the midbrain, known for reward-processing functionality.
The team found that these neurons were activated when the mice sought a sugar reward, regardless of whether the reward was obtained. In fact, when the GABAergic neurons were stimulated, the animals gnawed at the floor or empty space in their cages when no food was present. When the neurons were inhibited, only the sugar-seeking behaviours of the mice decreased, while their normal feeding behaviour was unchanged.
“We can reduce compulsive sucrose-seeking but not affect their normal feeding,” said study co-author Edward Nieh. “This is important because for treating compulsive eating behaviour, we only want to stop the unhealthy parts of eating and keep normal eating intact.”
These findings, if replicated in humans, could lead to treatment of eating disorders and perhaps even gambling and drug addiction, due to the similarity of the pathways that activate those types of behaviours.