Generating a feeling of satiety is one of the mechanisms by which new anti-obesity medications, such as Ozempic or Wegoy, promote weight loss, since when we feel full after eating a large meal our stomach sends signals to the brain to create the feeling of satiety and thus stop eating. If our stomach feels full, therefore, we do not eat more, and that is also why it is often recommended that people who are on a diet drink a glass of water before starting to eat.
Engineers from the Massachusetts Institute of Technology-MIT (United States) have based this suggestion on developing a capsule that is ingested and vibrates inside the stomach, where its vibrations activate the same receptors that detect when the stomach is distended, creating a illusory feeling of fullness.
The researchers carried out their tests with the Yorkshire breed of American pig (between four and six months old and weighing between 40 and 80 kg) and found that in the animals that received the pill 20 minutes before eating, it did not Not only did it stimulate the release of hormones that signal satiety, it also reduced their food intake by approximately 40%.
“For someone who wants to lose weight or control their appetite, they could take it before every meal,” said Shriya Srinivasan, a former MIT graduate student and postdoctoral fellow who is now an assistant professor of bioengineering at Harvard University and the lead author of the study. new study. “This could be really interesting because it would provide an option that could minimize the side effects that we see with other drug treatments that are out there.”
A minimally invasive way to treat obesity
There is much more to learn about the mechanisms that influence human body weight, but if new studies show that this technology could be used safely in humans, such a pill could offer a minimally invasive way to treat obesity, researchers say. authors of the study, which has been published in Science Advances.
When the stomach distends, specialized cells called mechanoreceptors detect it and send signals to the brain through the vagus nerve. The result is that the brain stimulates the production of insulin, as well as hormones such as C-peptide, Pyy, and GLP-1, all of which hormones act together to help people digest food, feel full, and stop eating. At the same time, levels of ghrelin, a hormone that promotes hunger, decrease.
While a graduate student at MIT, Srinivasan became interested in the idea of controlling this process through vibration, artificially stretching the mechanoreceptors that line the stomach. Previous research has shown that vibration applied to a muscle can induce the sensation that the muscle has been stretched more than it has actually been stretched.
“I was wondering if we could activate the stretch receptors in the stomach by vibrating them and making them perceive that the entire stomach has expanded, to create an illusory sensation of distension that could modulate hormones and eating patterns,” Srinivasan explained.
The vibrating pill not only stimulated the release of hormones that signal satiety in the animals, but also reduced their food intake by approximately 40%.
Srinivasan worked closely with the laboratory of Giovanni Traverso, an associate professor of mechanical engineering at MIT and a gastroenterologist at Brigham and Women’s Hospital, who has developed many novel approaches to oral drug delivery and electronic devices. Both scientists and a team of researchers designed a capsule the size of a multivitamin, which includes a vibrating element that is powered by a small silver oxide battery. When the pill reaches the stomach, acidic gastric fluids dissolve a gelatinous membrane that covers the capsule, completing the electronic circuit that activates the vibrating motor.
In an animal study, researchers showed that once the pill starts vibrating, it activates mechanoreceptors, which send signals to the brain by stimulating the vagus nerve. The researchers tracked hormone levels during periods when the device vibrated and found that they mirrored hormone release patterns seen after a meal, even when the animals had fasted.
They later tested the effects of this stimulation on the animals’ appetite and found that when the pill was activated for about 20 minutes before offering food, they consumed 40% less, on average, than when the pill was not activated. The animals also gained weight more slowly during the periods when they were treated with the vibrating pill.
“The behavior change is profound, and that means using the endogenous system instead of any exogenous treatment. “We have the potential to overcome some of the challenges and costs associated with the administration of biological drugs by modulating the enteric nervous system,” says Traverso.
The current version of the pill is designed to vibrate for about 30 minutes after reaching the stomach, but researchers plan to explore the possibility of adapting it to remain in the stomach for longer periods of time, where it could be turned on and off wirelessly. as necessary. In animal studies, the pills passed through the digestive tract in four to five days. The study also found that the animals did not show any signs of obstruction, perforation or other negative impacts while the pill was in their digestive tract.
According to the researchers, this type of pill could provide an alternative to current approaches to treating obesity, which include gastric bypass surgery, gastric balloons, or medications such as GLP-1 agonists, which are unaffordable for many people. According to Srinivasan, the MIT capsules could be manufactured at a cost that would make them available to people who do not have access to more expensive treatment options.
“For many populations, some of the most effective therapies for obesity are very expensive. At scale, our device could be manufactured at a fairly profitable price,” he highlights. “I would love to see how this would transform care and therapy for people in global health settings who may not have access to some of the more sophisticated or expensive options that are available today.”
