Astrocytes shown to regulate how much we eat.

It is known that neurons in an area of the brain called the hypothalamus control how much an animal eats. However, it is not clear what role other brain cells, such as glial cells, might play in influencing diet. Glial cells do not send nerve impulses like neurons, as they mostly serve to support and protect the neurons.  Now, researchers led by MIT show that glial cells play a critical role in controlling appetite and feeding behaviour.  The team state that 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 that the hypothalamus controls appetite as well as energy expenditure, body temperature, and circadian rhythms including sleep cycles. Earlier studies from the lab on glial cells in other parts of the brain showed that the hypothalamus also appeared to have a lot of glial cell activity.  Therefore, the group investigated what glial cells would be doing in the hypothalamus.  The current study shows that glial cells in the hypothalamus play a key role in controlling appetite and, when manipulated, induces or suppresses feeding behaviour.

The current study engineers astrocytes to produce a surface receptor which binds to a chemical compound known as clozapine-N-oxide (CNO); so when CNO is given, it activates the glial cells.  Results show that turning on astrocyte activity with just a single dose of CNO has a significant effect on feeding behaviour in mice.  Data findings show that over the course of three days the mice did not gain extra weight, even though they were eating more, and when astrocytic activity was silenced the mice ate less than normal.

The group state this raises the possibility that glial cells may also be modulating neurons, which control energy expenditures, to compensate for the increased food intake.  They go on to postulate that neurons may have multiple partners and modulate multiple energy homeostasis functions all at the same time.  The lab stress that it is still unknown as to how astrocytes exert their effects on neurons.

The team surmise their data shows that activating glia cells stimulates overeating and that when the cells are suppressed, appetite is also suppressed.  For the future, the researchers plan to develop new research tools which could help the global medical community to learn more about astrocyte-neuron interactions and how astrocytes contribute to modulation of appetite, and feeding.

Source: Singapore Bioimaging Consortium

Glial cells. Coloured scanning electron micrograph (SEM) of a glial cell (centre). Glial cells are nervous system cells that provide structural support and protection for neurons (nerve cells). In the human brain, the most concentrated region of glial activity is in the cerebral cortex, where there are about four glia for every neuron. Credit: THOMAS DEERINCK, NCMIR/SCIENCE PHOTO LIBRARY.


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