Scientists have taken a step closer to finding a drug for the difficult-to-treat eating disorder anorexia. In experiments with mice, the researchers showed that increasing levels of a peptide important to stimulating hunger could reverse anorexia symptoms. More research will be needed to figure out whether a similar approach can be safely and effectively done in humans, however.
Anorexia nervosa, or simply anorexia, is characterized by a persistent reduction in food intake, which then leads to health issues like low body weight, malnutrition, and heart disease. Anorexia is most commonly diagnosed in younger people (especially girls) and is often tied to a disordered body image and an obsessive fear of gaining weight. But other medical conditions can cause anorexia as well, particularly cancer or as a side effect of certain cancer drugs. It’s notoriously hard to treat, with only a third of sufferers thought to achieve remission with current interventions such as cognitive-behavioral therapy. And to date, there are no FDA-approved medications for anorexia.
Scientists from France and China led this latest research, which was published Wednesday in the journal Science Advances. Some past studies have shown that people with anorexia tend to have lower circulating levels of a protein called acyl-coenzyme A binding protein, or ACBP, which is known to stimulate hunger by helping activate or dampen certain neurons in the brain. The researchers found this same pattern in patients hospitalized with anorexia, with lower ACBP levels appearing to predict a higher risk of a person relapsing later on. This finding inspired the scientists to dig further and experiment with ACBP using mice.
ACBP is produced by many types of cells, but it isn’t released into the body the way most proteins are; instead, it’s released when cells are broken down. To work around this limitation, the researchers created a “chemical-genetic delivery system” that would prompt their mice’s liver cells to release ACBP on command when the mice were given supplements of biotin, or vitamin B7. The researchers induced anorexia symptoms in mice, using either chronic stress or chemotherapy drugs, then raised ACBP levels using biotin.
In mice with both forms of anorexia, the increase of ACBP reversed their symptoms, the researchers found. Biologically, the added ACBP also appeared to reverse the activity of melanocortin 4 receptors in the brain’s hypothalamus, which are known to play a part in suppressing appetite. A similar reversal was seen when the mice were given more ACBP intravenously or via a subcutaneous pump.
“The supplementation of [ACBP] was able to impede the loss of body fat, lean weight, and bone mass present in several models of anorexia,” the researchers wrote.
While this research does point to the eventual possibility of a drug for anorexia, the scientists caution that more work is needed to untangle exactly how ACBP affects appetite in humans. Anorexia in humans is also often a complex disorder affected by psychological or other factors (including social media) that can’t be modeled easily in mice. And it will probably take time to find a stable and effective form of ACBP that can be safely used in people. So the actual implementation of ACBP-based medications will definitely require further development, the researchers say. Still, given the lack of other treatment options now, this line of research is definitely promising.
