Hungry for love: Gut molecule discovered that flips the feeding-to-
mating switch

Date:
February 9, 2022
Source:
University of California - San Diego
Summary:
Scientists have identified a molecule released from the gut after a
protein-rich meal that switches the focus of fruit flies from eating
to courtship. The discovery of Dh31, a type of chemical messenger,
opens the door to unexplored areas of gut-to-brain communication.



FULL STORY ==========================================================================
On Valentine's Day, couples all over the world will enjoy romantic dinners
to celebrate love and relationships. The association between nutrition and mating is not unique to humans but is reflected across species throughout
the animal kingdom. However, direct physiological links connecting food consumption and reproductive behaviors were not suspected until recently.


========================================================================== Scientists from the University of California San Diego studying fruit
flies report that a molecule released from the gut after a meal switches
their focus from eating to mating. Publishing in the journal Nature,
the researchers found that protein-rich food triggers the release of
diuretic hormone 31, or "Dh31," a signaling molecule discovered to be
released from the fly's gastrointestinal tract. Their identification of
Dh31, a neuropeptide considered to be a type of chemical messenger, opens
the door to the largely unexplored area of gut-to- brain communication
beyond feeding behavior.

"We found the transition from feeding to mating and were very surprised
that a single molecule would have such a profound influence on behavior decisions," said Jing Wang, a professor of Neurobiology in the UC San
Diego Division of Biological Sciences and the study's senior author. "Our
study provides a mechanistic explanation of how the Dh31 neuropeptide
acts on the brain to change the motivational drive of two evolutionarily critical behaviors." In investigating the question of how animals
change from a feeding-focused behavior to a mating mindset, UC San
Diego researchers and their colleagues at UC Santa Cruz used several
methods to arrive at their Dh31 molecule discovery, including genetics, three-photon microscopy and fluorescence imaging.

To confirm their finding, the researchers performed genetics experiments
in which Dh31 was knocked out of fruit flies. In these cases, the flies
kept feeding and held off mating behavior. In other experiments they
activated Dh31 and found the flies rapidly flipped to courtship. Instead
of the brain, an expected area for the molecule's release, they found
Dh31 originated in the fly's gut.

"These results indicate that Dh31 is a signaling molecule that reorders
the priority of these two contending behaviors: feeding over courtship
in the absence of Dh31 and courtship over feeding when Dh31 is released
from the gut," said Wang.

The researchers further described parallels to Dh31's function as a
signaling molecule. Orexin, a neuropeptide molecule, has proven to play
a similar role in mammals in the transition from wakefulness to sleep
patterns, including rapid eye movement (REM) sleep and non-REM sleep.

These explorations provide insight into decision-making processes
when animals switch from one behavior that promotes survival -- such
as nourishment intake - - to a different fundamental behavior such
as courtship. Wang said their findings only scratch the surface of understanding how gut hormones function beyond feeding. Future work will investigate how microbiomes factor into gut- to-brain communication.

"This work embodies a multidisciplinary approach to understand behavioral prioritization at multiple levels, from molecules to neurons and circuit function," said Wang. "This line of work provides us with an empirical
paradigm to study the hierarchical organization of different need-based behaviors, a framework established by Abraham Maslow 80 years ago to
explain the orderly transition of human behaviors." The scientists who contributed to the study include: Hui-Hao Lin, Meihua Christina Kuang,
Imran Hossain, Yinan Xuan, Laura Beebe (graduate student), Andrew
Shepherd, Marco Rolandi and Jing Wang.

========================================================================== Story Source: Materials provided by
University_of_California_-_San_Diego. Original written by Mario Aguilera
with contributions from Susy Kim. Note: Content may be edited for style
and length.


========================================================================== Journal Reference:
1. Hui-Hao Lin, Meihua Christina Kuang, Imran Hossain, Yinan Xuan,
Laura
Beebe, Andrew K. Shepherd, Marco Rolandi, Jing W. Wang. A
nutrient- specific gut hormone arbitrates between courtship and
feeding. Nature, 2022; DOI: 10.1038/s41586-022-04408-7 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/02/220209112211.htm

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