Eating for hunger or pleasure? Regulating these feeding behaviors
involves different brain circuits

Date:
July 27, 2021
Source:
Baylor College of Medicine
Summary:
Researchers discovered that although the brain regulates feeding
for pleasure and for hunger through serotonin-producing neurons in
the midbrain, each type of feeding is wired by its own independent
circuit that does not influence the other type of feeding.



FULL STORY ==========================================================================
Many times we eat, not because we are hungry, but because of social
pressures or because the food is so appetizing, that, even though we
are full, we just want another bite.


========================================================================== Overeating, whether it is guided by hunger or pleasure, typically leads
to obesity, which affects about 42% of the adults in the U.S., according
to the Centers for Disease Control and Prevention. Looking to contribute
to the development of effective treatments for obesity, an international
team led by researchers at Baylor College of Medicine investigated in
an animal model how the brain regulates feeding triggered by hunger or
other factors.

Led by Dr. Yong Xu, professor of pediatrics -- nutrition and molecular and cellular biology at Baylor, the team discovered that although the brain regulates both types of feeding behavior through serotonin-producing
neurons in the midbrain, each type of feeding is wired by its own
independent circuit that does not influence the other type of feeding. The researchers also identified two serotonin receptors and two ion channels
that can affect the feeding behaviors, opening the possibility that
modulating their activities might help regulate overeating. The study
appears in the journal Molecular Psychiatry.

Mapping the roads that control feeding behavior in the brain Xu
and his colleagues identified two distinct brain circuits formed by serotonin-producing neurons in the midbrain. One of the circuits extends
to the hypothalamus, while the other projects into another region of
the midbrain.

These circuits play very distinct roles in regulating feeding.

"We discovered that the circuit that projects to the hypothalamus
primarily regulates hunger-driven feeding, but does not influence the non-hunger driven feeding behavior," Xu said. "The other circuit that
projects into the midbrain regulates primarily the non-hunger driven
feeding, but not the feeding behavior triggered by hunger. This indicates
that, at the circuit level, the brain wires the two types of feeding
behavior differently." The other significant contribution of this work
refers to the identification of potential molecular targets associated
with the circuits that could be used to treat overeating.

"One potential target is serotonin receptors, which are molecules that
mediate the functions of the neurotransmitter serotonin produced by
the neurons," Xu explained. "We found that two receptors, serotonin 2C
receptor and serotonin 1B receptor, are involved in both types of feeding behavior. Our data suggests that combining compounds directed at both
receptors might produce a synergistic benefit by suppressing feeding."
In addition, the team identified ion channels associated with the
circuits that also might offer an opportunity to regulate the feeding behaviors. "One is the GABA A receptor, a chloride channel, found to be important in regulating serotonin circuits during hunger-driven feeding,
but not during non-hunger driven feeding," Xu said.

The other is a potassium channel that influences feeding triggered by
hunger- independent cues, but not hunger-driven feeding. "There is a
clear segregation of these two ion channels," Xu said. "They have distinct functions in feeding behavior, which suggests they also could be target candidates to regulate overeating." The findings have encouraged the researchers to conduct future studies to identify more molecules that
could modulate the activity of the ion channels to produce anti-overeating effects in animal models. "We also want to explore how external factors
related to nutrition might affect ion channel functions at the molecular level," Xu said.

========================================================================== Story Source: Materials provided by Baylor_College_of_Medicine. Original written by Homa Shalchi. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Yanlin He, Xing Cai, Hailan Liu, Krisitine M. Conde, Pingwen Xu,
Yongxiang Li, Chunmei Wang, Meng Yu, Yang He, Hesong Liu, Chen
Liang, Tingting Yang, Yongjie Yang, Kaifan Yu, Julia Wang, Rong
Zheng, Feng Liu, Zheng Sun, Lora Heisler, Qi Wu, Qingchun Tong,
Canjun Zhu, Gang Shu, Yong Xu. 5-HT recruits distinct neurocircuits
to inhibit hunger-driven and non-hunger-driven feeding. Molecular
Psychiatry, 2021; DOI: 10.1038/ s41380-021-01220-z ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/07/210727131444.htm

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