Estrogens are best known as hormones that regulate sexual development in women, although men produce them as well. Now, a new study finds that a particular kind of estrogen might have an additional role to play in suppressing appetite.
While the majority of estrogen produced by humans is synthesized in the ovaries of women, the messenger molecules are actually produced elsewhere in the body by both men and women. In fact in men, about 20% of the hormones are made by the testes, while the rest comes from the conversion of testosterone through an enzyme known as aromatase in the brain, skin, bone, and fatty tissue. Women, too, produce a portion of their estrogen from these other sources as well, thanks again to the actions of aromatase.
Estrogens are also produced by central nervous system cells such as those found in the brain's hypothalamus. When the hormones come from this mode of production, they are referred to as neuroestrogens. Neuroestrogens have previously been studied for their role in shaping male sexual and social behaviors but researchers from the Fujita Health University School of Medical Science in Japan decided to look at it for another reason: appetite control.
In a rodent study, they knocked out the gene that encodes aromatase. This kept the genetically altered mice from being able to synthesize estrogens anywhere throughout their bodies. These mice showed increased food intake and weight gain over a control group where aromatase functioned normally.
When the gene was turned back on, and the rodents' brains began producing aromatase again, they were found to have an increased sensitivity to leptin, a molecule often referred to as the "fullness hormone," thanks to its effects in the brain in regulating hunger.
To confirm that it was the neuroestrogens that were having the appetite-regulating effect, the researchers then studied mice that had their ovaries removed. This would mean that all of the estrogens in their systems were being produced through other methods. In this group of mice, the researchers noticed that the hypothalamus region in their brains began to increase its expression of the gene that encodes aromatase, leading to a decreased food intake.
While it's unknown if the study's findings will transfer to humans, and it doesn't confirm a way to adjust food intake through any kind of aromatase or neuroestrogen regulation, it does add information to a growing body of research linking estrogen and appetite.
“Our results imply that neuroestrogens likely contribute to appetite regulation and may be relevant for body weight reduction” the authors wrote in a paper describing the study published in the FEBS Journal. "These observations advance our understanding of the intricate roles neuroestrogens play in regulating metabolic functions and energy homeostasis."
Source: Wiley via EurekAlert
