Estrogen generated in the brain may play a role in regulating appetite, potentially opening new avenues for treating obesity.
Estrogen has long been known as the hormone that helps regulate reproduction and is mainly produced in the ovaries. But scientists have recently uncovered a surprising twist: your brain makes its own form of estrogen too.
This brain-made version is called neuroestrogen, and it’s produced with the help of an enzyme called aromatase. Although researchers have known about neuroestrogen for a while, they weren’t quite sure what it actually did—until now.
A research team from Fujita Health University in Japan has made a groundbreaking discovery: neuroestrogen plays a direct role in controlling appetite.
“It is well known that MC4R (melanocortin-4 receptor) is an important receptor in the brain that regulates food intake,” explains lead author Takanori Hayashi, Associate Professor at Fujita Health University School of Medicine, Japan.
Dr. Hayashi, along with co-lead Dr. Eiji Nishio, collaborated with scientists at Chiba University and Fukuoka University to explore how neuroestrogen affects hunger. Their findings were recently published in The FEBS Journal.
Using specially bred mice, the team compared animals that couldn’t produce estrogen to those with active brain estrogen. The results were striking: mice lacking ovaries or the aromatase enzyme (needed to make neuroestrogen) ate more food and gained more weight than their normal counterparts.
Restoring Brain Estrogen Reduces Hunger
However, when the aromatase gene was selectively reactivated in the brains of ArKO mice (BrTG-ArKO strain), the animals exhibited significantly lower food intake as compared to the former group. They also showed a marked increase in the expression of MC4R in the hypothalamus. This highlights that the neuroestrogen produced by aromatase was involved in the expression of MC4R and thereby led to the suppression of hunger.
Furthermore, the study also revealed that neuroestrogen could enhance the brain’s responsiveness to leptin, a hormone produced by fat cells that helps regulate hunger.
“We observed that the mice with restored neuroestrogen responded more effectively to leptin treatment,” explains Dr. Hayashi. “This may be because neuroestrogen enhances the body’s natural appetite-suppressing mechanisms.”
Additionally, the researchers conducted cell culture experiments to confirm how neuroestrogen could directly increase MC4R levels in hypothalamic neurons. This provides further evidence that its effects are localized and not dependent on estrogen from the ovaries.
Implications for Obesity and Hormonal Health
Hailing the success of their discovery, Dr. Hayashi remarks, “With its newly discovered role, neuroestrogen could be a game-changer in controlling appetite and tackling obesity!”
As global obesity rates continue to climb and conventional weight loss treatments often fall short, this ability to influence appetite via the brain’s own hormone opens an exciting new frontier for clinical research and drug development.
Emphasizing the significance of their research, the researchers note that as we gain a clearer understanding of neuroestrogen’s physiological role, it may become possible to regulate estrogen activity more precisely within the body. This could have far-reaching implications for women’s health, especially in managing life-stage hormonal challenges such as menopause or postpartum weight gain.
The study marks a major step forward in understanding how our brains regulate hunger and energy balance. By unlocking how neuroestrogen interacts with other hormones, researchers hope to develop innovative treatments that target appetite at its source—inside the brain.
Reference: “Estrogen synthesized in the central nervous system enhances MC4R expression and reduces food intake” by Takanori Hayashi, Kanako Kumamoto, Tatsuya Kobayashi, Xinfeng Hou, Shizuko Nagao, Nobuhiro Harada, Shinichiro Honda, Yohei Shimono and Eiji Nishio, 18 February 2025, The FEBS Journal.
DOI: 10.1111/febs.17426
Funding: Japan Society for the Promotion of Science
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