A recently published study in Neuron reports on the function of glutamatergic neurons in mice. The researchers from the University of Washington had previously discovered that these cells lit up in obese mice and prevented signals that indicated satiety.
The researchers found that these neurons communicate to two different brain regions: the lateral habenula, a key brain region in the pathophysiology of depression, and the ventral tegmental area, best known for the major role it plays in motivation, reward, and addiction. “We found these cells are not a monolithic group, and that different flavors of these cells do different things,” said lead author Garret Stuber.
Their recent study systematically analyzed the lateral hypothalamic glutamate neurons. Researchers found that, when mice are being fed, the neurons in the lateral habenula are more responsive than those in the ventral tegmental area, suggesting that these neurons may play a greater role in guiding feeding.
The scientists also looked at the influence of the hormones leptin and ghrelin on how we eat. Both leptin and ghrelin are thought to regulate behavior through their influence on the mesolimbic dopamine system, a key component of the reward pathway in the brain. But little has been known about how these hormones influence neurons in the lateral hypothalamic area of the brain.
The investigators found that leptin blunts the activity of neurons that project to the lateral habenula and increases the activity of neurons that project to the ventral tegmental area. But ghrelin does the opposite. This study indicated that brain circuits that control feeding at least partially overlap with brain circuitry involved in drug addiction.