Nursing mothers experience significant metabolic demands, requiring an increase in food intake and energy conservation. This adaptation is linked to hormonal changes, particularly involving prolactin and estrogen. Researchers from Baylor College of Medicine and Pennington Biomedical Research Center recently published a study in Nature Metabolism that provides insights into these mechanisms.
Dr. Chunmei Wang from Baylor commented, "We worked with animal models to investigate how hormones and the brain work together to adapt to the metabolic demands nursing mothers face to sustain milk production."
According to Dr. Yanlin He at Pennington Biomedical Research Center, "Normally, estrogen helps control appetite and increases the body's ability to burn fat, while prolactin does the opposite. During lactation, estrogen levels drop, and prolactin levels rise, leading to increased hunger and reduced fat-burning to compensate for extra energy demands posed by milk production and consumption."
The study identified that "brain cells called estrogen receptor α (ERα) neurons in a small area of the hypothalamus are significantly less active during lactation," as explained by Dr. Meng Yu, a postdoctoral associate in the Wang lab. The deletion of ERα neurons leads to a rise in prolactin levels and increased appetite paired with decreased fat burning.
Dr. He further noted that removing ERα neurons in non-lactating mice resulted in "high prolactin levels and lactation-like changes – eating more and burning less fat." Reactivating these neurons reversed these effects, demonstrating their role in metabolic control.
Dr. Wang expressed excitement about discovering a "novel mechanism for prolactin regulation," describing how estrogen can activate ERα neurons, thereby inhibiting prolactin levels during lactation. This insight could have clinical applications.
Dr. He mentioned the broader implications of the research, noting, "The study sheds light on how the brain integrates hormonal signals to regulate energy balance, which could have broader implications for understanding hyperprolactinemia – high levels of prolactin in the blood – obesity, menopause and other conditions where prolactin or estrogen levels shift. This work opens exciting avenues for future research on neuroendocrine control of metabolism."
The research team also included Bing Feng, Jonathan C. Bean, and several others from Baylor, Pennington Biomedical, and the University of Illinois at Chicago. The study was funded by various grants from organizations like the National Institutes of Health, USDA, American Heart Association, and Department of Defense.
