Neurons in an area of the brain known as the hypothalamus control how much an animal eats, however, it is not clear what role the brain’s immune cells, known as glial cells, play in influencing diet. In rare cases glial cells have been known to send nerve impulses like neurons, however, they mostly serve to support and protect the neurons. Now, researchers led by MIT show glial cells play a critical role in controlling appetite and feeding behavior. The team states their findings could offer scientists a new target for developing drugs against obesity and other appetite-related disorders. The opensource study is published in the journal eLife.
Previous studies show the hypothalamus controls appetite, as well as energy expenditure, body temperature, and the circadian rhythm. Earlier studies from the lab on glial cells in other parts of the brain showed the hypothalamus also appeared to have a lot of microglia cell activity. Therefore, the group investigated the activity of glial cells in the hypothalamus. The current study shows glial cells in the hypothalamus play a key role in controlling appetite and, when manipulated, induces or suppresses feeding behavior.
The current study engineers astrocytes to produce a surface receptor capable of binding to a chemical compound known as clozapine-N-oxide (CNO), meaning when CNO is bound to receptors, it activates glial cells. Results show turning on astrocytic activity with just a single dose of CNO has a significant effect on feeding behavior in mice. Data findings show over the course of three days the mice did not gain extra weight even though they were eating more, in contrast, when astrocytic activity was silenced the mice ate less than normal.
The group states this raises the possibility glial cells may also be modulating neurons to control energy expenditures, compensating for the increased food intake. They go on to postulate neurons may have multiple partners to aid in the modulation of multiple energy-based homeostatic functions simultaneously. The lab stresses it is still unknown as to how astrocytes exert their effects on neurons.
The team surmises their data shows activating glial cells stimulates overeating, with appetite dampened when the cells are suppressed. For the future, the researchers plan to develop new research tools which could help the global medical community to learn more about microglia-neuron interactions and how astrocytes contribute to the modulation of appetite and feeding.
Source: Food Navigator
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