New research from the University of Bonn has found that stimulation of the vagus nerve strengthens communication between the stomach and the brain, creating a new obesity treatment.
The nervous system takes in sensory stimuli, processes them and triggers reactions such as muscle movements or pain sensations in the body. In recent years, research has found a network in the brain that is linked to signals in the stomach, presumably this nervous network influences feelings of hunger and satiety in the body.
Now, a research team led by Dr Nils Kroemer of the University Hospitals of Tübingen and Bonn has discovered that non-invasive stimulation of the vagus nerve in the ear can strengthen the communication and brain within minutes, opening up the potential for new obesity treatment. Researchers also believe their findings could be used to develop treatments for depression and eating disorders
Nerve stimulation can alter human behaviour
The vagus nerve is responsible for multiple aspects of human behaviour. It is a cranial nerve that connects several important organ systems to the brain and, therefore, supports the transmission of endogenous signals through the body. These signals help in the goal-directed search for food by re-tuning the brain’s reward system when the stomach is empty.
Previous research has found that the vagus nerve can regulate digestion via the brain. If stimulated correctly, this mechanism has relevant therapeutic applications as an obesity treatment. As well as this, vagus nerve stimulation would be a non-invasive obesity treatment, increasing its therapeutic potential.
The new study has addressed the previously unanswered question of how exactly the modulation via the brain works.
The research team studied a total of 31 participants. They combined stimulation of the vagus nerve in the ear with simultaneous recording of brain activity via functional magnetic resonance imaging (MRI) and an electrogastrogram. The electrogastrogram works by placing electrodes – similar to an ECG – over the stomach to record signals from the participant’s digestive act.
“We showed for the first time that electrical stimulation strengthens the coupling between signals from the stomach and the brain – and we can do it within a few minutes,” Dr Kroemer said.
The researchers stimulated both the vagus nerve in the ear and, other nerves in the ear of each participant, in a controlled environment.
“We observed that vagus nerve stimulation increased coupling with signals from the stomach in the brainstem and midbrain. These regions are important because they are the first targets of the vagus nerve in the brain. Changes in the midbrain may already mediate our actions,” explained Dr Kroemer.
Genuine potential for use as an obesity treatment
Additionally, the researchers found that coupling with the stomach increased throughout the brain, especially in regions that already communicated strongly with the stomach before stimulation. Changes in coupling between the stomach and brain can be produced instantaneously and spread rapidly.
The researchers believe their findings have genuine therapeutic potential as an obesity treatment. Kroemer believed the stimulation of the vagus nerve could help affected induvial restore their perception of body signals in the future.
Dr Kroemer’s team is currently also conducting further research into a potential application for depression. Communication between the nervous system and brain has already been identified as a key factor in depression.
