DALLAS — A commonly prescribed class of migraine drugs called Triptans may prove useful in the fight against obesity. Scientists from UT Southwestern report a group of obese mice given a daily dose of a triptan ate less food and lost weight over the course of a month.
“We’ve shown that there is real potential to repurpose these drugs, which are already known to be safe, for appetite suppression and weight loss,” says study leader Chen Liu, Ph.D., Assistant Professor of Internal Medicine and Neuroscience and an investigator in the Peter O’Donnell Jr. Brain Institute, in a university release.
It’s currently estimated that obesity affects over 41 percent of U.S. adults. Obesity is known to increase a person’s risk of heart disease, stroke, diabetes, and even certain cancers.
Previous studies have shown that serotonin, a chemical messenger found throughout the brain and body, plays a major role in appetite. However, there are actually 15 distinct types of serotonin “receptors,” or molecules that can sense serotonin and consequently signal for cells to change their behavior.
So far, science has largely struggled to make sense of the role each receptor type plays in determining appetite outcomes. For example, previous drugs like fen-phen and lorcaserin (Belviq) which only target certain individual receptors have since been removed from the market over their harmful side-effects.
What makes triptans different?
Triptans are usually used to treat acute migraines and cluster headaches. These drugs work by targeting an entirely different receptor – the serotonin 1B receptor (Htr1b). Until now, Htr1b had not been thoroughly studied within the context of appetite and weight loss.
For this new project, the research team tested six prescription triptans among a group of obese mice being fed a high-fat diet for seven weeks. Mice given two of the triptans ate roughly the same amount, but mice given any of the other four ended up eating less.
After 24 days, rodents who had been given a daily dose of the drug frovatriptan showed an average body weight reduction of 3.6 percent. Mice not given a triptan gained an average of 5.1 percent of their body weight. Moreover, similar findings were noted when researchers implanted the rodents with a device supplying a steady dose of frovatriptan for 24 days.
“We found that these drugs, and one in particular, can lower body weight and improve glucose metabolism in less than a month, which is pretty impressive,” Dr. Liu adds.
Why don’t migraine patients regularly lose weight?
Dr. Liu theorizes patients haven’t noticed the longer-term impacts (or benefits if you’re looking to lose weight) of these drugs yet because triptans are typically only prescribed for short-term use to treat migraines.
In order to determine how exactly frovatriptan influences eating habits and weight outcomes, the research team engineered a group of mice lacking either Htr1b or Htr2c (the serotonin receptor targeted by fen-phen and lorcaserin). Mice without Htr1b didn’t experience the same weight loss or appetite reduction while taking frovatriptan. Cutting out Htr2c, however, had no effect. This confirms, researchers explain, that the drugs work via the targeting of the serotonin 1B receptor.
“This finding could be important for drug development,” Dr. Liu concludes. “We not only shed light on the potential to repurpose existing triptans but also brought attention to Htr1b as a candidate to treat obesity and regulate food intake.”
The research team was even able to locate exactly which neurons in the brain were most important to Htr1b when it came time to mediate appetite — zeroing in on a small group of cells within the brain’s hypothalamus.
The study is published in the Journal of Experimental Medicine.