Ingestible capsules are covered with grooves that allow liquid to escape
J. McRae (MIT)
Tablets that electrically stimulate the stomach cells of pigs are used to increase levels of ghrelin, a hormone that regulates hunger and relieves nausea. If applied to humans, this technology could potentially treat nausea, vomiting, and anorexia in people with eating disorders and people undergoing cancer treatment.
Current interventions using electrical stimulation to relieve gastrointestinal symptoms require invasive surgery. So Giovanni Traverso and his colleagues at the Massachusetts Institute of Technology designed a noninvasive capsule the size of a raisin to deliver a small dose of stimulation.
Inside the capsule, a battery generates an electric current that flows along the gold wire wound on the outside. Grooves etched into the surface of the capsule allow fluid to escape, and wires electrically stimulate receptors in stomach tissue, causing the release of ghrelin. It is coated with a thin casing that protects the
Traverso and his team tested the capsules in 13 pigs that were fasted overnight and given an anesthetic. Eleven animals he received 20 minutes of stimulation and his other two did not.
The researchers measured blood levels of ghrelin before and 10 minutes after stimulation. They found that, on average, ghrelin increased by about 40% in stimulated pigs, while ghrelin decreased by about 50% in unstimulated pigs.
“The levels we see are comparable to those expected to induce hunger or suppress nausea, but we haven’t evaluated them. [symptoms] In animals,” says Traverso. “Part of our next steps will include doing this in humans to understand if we can use this system to treat nausea.”
All animals excreted the capsules within two weeks, which is a normal period for pigs, says Traverso. Tissue samples taken from the stomach, duodenum and colon showed no changes or signs of trauma, suggesting that the treatment is safe.
“To my knowledge, this is the first ingestible device that can provide electrical stimulation to the gastrointestinal tract,” says Stavros Zanos of the Feinstein Institute for Medical Research in New York. This technique can be fine-tuned to provide electrical stimulation to other gut tissues such as the colon.
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