Unraveling the mystery of why we overeat

Date:
October 12, 2021
Source:
University of Washington School of Medicine/UW Medicine
Summary:
Researchers are examining neurons and hormones associated with
eating too much. This study is another step in understanding the
brain circuits involved in eating disorders.



FULL STORY ========================================================================== Eating is one of life's greatest pleasures, and overeating is one of
life's growing problems.


==========================================================================
In 2019, researchers from The Stuber Lab at the University of Washington
School of Medicine discovered that certain cells light up in obese mice
and prevent signals that indicate satiety, or feeling full. Now comes
a deeper dive into what role these cells play.

A study published Oct. 7 in the journal Neuronreports on the function
of glutamatergic neurons in mice. These cells are located in the lateral hypothalamic area of the brain, a hub that regulates motivated behaviors, including feeding.

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 Stuber, a joint UW
professor of anesthesiology and pain medicine and pharmacology. He works
at the UW Center for the Neurobiology of Addiction, Pain, and Emotion,
and was the paper's senior author. Mark Rossi, acting instructor of anesthesiology and pain medicine, is the lead author.

The study is another step in understanding the brain circuits involved
in eating disorders.

The Stuber Lab studies the function of major cell groups in the brain's
reward circuit, and characterizes their role in addiction and mental
illness -- in hopes of finding treatments. One question is whether these
cells can be targeted by drugs without harming other parts of the brain.

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.

Researchers 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.

The study adds to the growing body of research on the role of the brain in obesity, which the World Health Organization calls a global epidemic. New
data from the Centers for Disease Control and Prevention showed 16
states now have obesity rates of 35% or higher. That's an increase of
four states -- Delaware, Iowa, Ohio and Texas -- in just a year.

========================================================================== Story Source: Materials provided by University_of_Washington_School_of_Medicine/UW_Medicine.

Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Mark A. Rossi, Marcus L. Basiri, Yuejia Liu, Yoshiko Hashikawa,
Koichi
Hashikawa, Lief E. Fenno, Yoon Seok Kim, Charu Ramakrishnan,
Karl Deisseroth, Garret D. Stuber. Transcriptional and functional
divergence in lateral hypothalamic glutamate neurons projecting
to the lateral habenula and ventral tegmental area. Neuron, 2021;
DOI: 10.1016/ j.neuron.2021.09.020 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/10/211012102654.htm

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