Could an oxytocin nasal spray improve self-control and reduce obesity?
The researchers - led by Franziska Plessow, PhD, from Harvard Medical School and the Massachusetts General Hospital in Boston - presented their findings last weekend at the Endocrine Society's 98th annual meeting.
Oxytocin is a hormone produced in the brain that is then transported to the pituitary gland. It is often referred to as the "love hormone" for its role in sex, birth and breastfeeding.
It is also important for controlling food intake and weight.
A synthetic form of oxytocin is available in the US as an intravenous or injectable drug - called Pitocin - to induce labor.
Although oxytocin nasal spray is approved in Europe, it is not currently approved in the US outside of clinical trials.
Last year, researchers from Massachusetts General Hospital announced that the nasal spray encouraged participants in a test meal to reduce caloric and fat intake without affecting appetite, but the team was not able to determine how the spray had this effect.
New treatment strategy for obesity?
"Knowing the mechanisms of action of intranasal oxytocin is important to investigating oxytocin as a novel treatment strategy for obesity," says Plessow.
- Oxytocin is made in the hypothalamus
- It acts as both a hormone and a brain neurotransmitter
- Called the "love hormone," it plays a role in sex, birth and breastfeeding.
To further investigate how study subjects' impulsive behavior could be suppressed, she and her colleagues conducted a stop-signal task.
This is a psychological research test in which subjects sit in front of a computer and are trained to respond to a square symbol on the screen by pressing a button on the left side of the keyboard, and they respond to a triangle by pressing a button on the right.
Once the subjects become familiar with this task, they were told not to press a button when they saw a symbol, but rather when they heard a beep.
The beeps occurred after the symbols popped up with varying delays that were adjusted to each subject. As such, the researchers say the new task required the subjects to control their behavioral impulse to respond.
The study subjects, who were 10 males aged from 23-43 years and who were overweight or obese, took the test on two different occasions, 15 minutes after they sprayed a dose of nasal spray in each nostril.
One day they received oxytocin, and on another day they received a placebo. The study was double-blind, so neither the men nor the testers knew which treatment they received.
Oxytocin lowers food intake by improving self-control
Results showed that after receiving the oxytocin, the men pressed the button less frequently when they were not supposed to.
The researchers say this showed that they had more control over their behavior and were acting less impulsively after receiving the oxytocin nasal spray.
These results suggest that oxytocin lowers food intake by improving self-control, says Plessow, who adds that "this information may allow us to move forward to large clinical trials, identify who can benefit from the drug and help optimize the treatment."
Because the study was only conducted in men, the researchers say they will need to test the drug in women. Additionally, they need to further investigate how oxytocin changes self-control, as well as how much of a role this mechanism plays in regulating food intake; not all overeating is rooted in self-control issues.
Still, Plessow says their results are "promising," and she adds that the spray "showed no strong side effects and is not as invasive as obesity surgery."
Medical News Today reported on a study presented at the Endocrine Society's annual meeting in 2015, which found that oxytocin nasal spray reduced caloric intake in healthy men.