2023-04-28 14:56:57
Hormones released by the stomach, such as ghrelin, play a key role in stimulating appetite. These hormones are produced by endocrine cells that are part of the enteric nervous system, which controls hunger, nausea, and feelings of satiety.
A team of MIT engineers has shown that they can stimulate these endocrine cells to produce ghrelin, using an ingestible capsule that sends an electrical current to the cells. This approach could prove useful for the treatment of conditions involving nausea or loss of appetite, such as cachexia (loss of body mass that can occur in patients with cancer or other chronic diseases). Their study is published in “Science Robotics.”
In animals, the researchers showed that this capsule could significantly increase the production of ghrelin in the stomach. They believe this approach could also be adapted to deliver electrical stimulation to other parts of the intestinal tract.
“This study helps establish electrical stimulation by ingestible electro-ceuticals as a way to trigger hormone release through the gastrointestinal tract,” says Giovanni Traverso, MIT professor, gastroenterologist at Brigham and Women’s Hospital, and lead author of the study. . “We show an example of how we can interact with the mucosa of the stomach and release hormones, and we anticipate that this could be used in other sites of the gastrointestinal tract that we have not analyzed in this work.”
The enteric nervous system controls all aspects of digestion, including the movement of food through the GI tract. Some patients with gastroparesis, a disorder of the stomach nerves that leads to very slow movement of foods, have shown symptomatic improvement after electrical stimulation generated by a pacemaker-like device that can be surgically implanted in the stomach.
Doctors thought that the electrical stimulation would cause the stomach to contract, helping to push the food out. However, it was found that while the treatment helped patients feel better, it affected motility to a lesser degree.
The MIT team hypothesized that electrical stimulation of the stomach might be triggering the release of ghrelin, which is known to promote hunger and reduce feelings of nausea.
to try that hypothesis, the researchers used an electrical probe to deliver electrical stimulation to the stomachs of the animals. They found that after 20 minutes of stimulation, ghrelin levels in the bloodstream rose considerably. They also found that electrical stimulation did not lead to any significant inflammation or other adverse effects.
Once they established that the electrical stimulation was causing the release of ghrelin, the researchers set out to see if they could accomplish the same thing using a device that could be swallowed and temporarily reside in the stomach. One of the main challenges in designing such a device is ensuring that the capsule’s electrodes can come into contact with stomach tissue, which is lined with fluid.
The capsule surface consists of grooves with a coating hydrophilic. These grooves function as channels that draw fluid from the stomach tissue. Inside the device are battery-powered electronics that produce an electrical current that flows through electrodes on the capsule’s surface. In the prototype used in this study, the current runs constantly, but future versions could be designed so that the current can be turned on and off wirelessly, according to the researchers.
Researchers tested their capsule by administering it into the stomach of large animals and found that the capsule produced a substantial increase in ghrelin levels in the bloodstream.
This treatment could replace or complement some of the existing medications used to prevent nausea and stimulate appetite in people with cachexia or anorexia.
«To the best of our knowledge, this is the first example of the use of electrical stimulation via an ingestible device to increase endogenous levels of hormones in the body, such as ghrelin.. And so, it has the effect of using the body’s own systems instead of introducing external agents,” explains researcher Khalil Ramadi.
The researchers found that for this stimulation to work, the vagus nerve, which controls digestion, must be intact. They believe that electrical pulses are transmitted to the brain via the vagus nerve, which then stimulates endocrine cells in the stomach to produce ghrelin.
Traverso’s lab now plans to explore the use of this approach in other parts of the GI tract, and the researchers hope to test the device in human patients within the next three years. If developed for use in human patients, this type of treatment could potentially replace or complement some of the existing drugs used to prevent nausea and stimulate appetite in people with cachexia or anorexia, the researchers say.
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