On Having Guts and Brains
The vagus nerve is a necessary part of the autonomic nervous system that sends and mediates information from the body to the brain and vice versa. It runs from the brainstem and down through the neck, chest and diaphragm and into the abdomen, all while branching out to innervate various organs and structures. It’s one beast of a nerve.
Its specific innervation of the gastrointestinal tract makes it an integral component of the “brain-gut” axis, a network with links also to gut microbiota and the endocrine, immune and humoral systems. In order to treat disorders of this complex system, such as Inflammatory Bowel Disease (IBD), researchers now focus on stimulating the vagus nerve, aka VNS (vagus nerve stimulation), as a therapeutic means. But how exactly?
- One effect of IBD is the body’s inability to downregulate inflammatory responses, leading to a chronically inflamed intestine.
- This chronic inflammation is due to the release of proinflammatory cytokines, including TNF-alpha.
- However, VNS has been shown to help reduce the systemic inflammatory response to intestinal inflammation by inhibiting the production of TNF-alpha and other inflammation-inducing cytokines.
A common way for VNS to treat inflammatory diseases is by surgically implanting a pulse generator device into the left mid-cervical vagus nerve. But some limitations and unfavorable side effects have rendered it a no-go. One team of researchers took it upon themselves to test a new site of stimulation: directly on the vagus nerve of the abdomen. So how does this work?
- First, they developed a safe, biocompatible electrode array to chronically implant into the abdominal vagus nerve in sheep to test how its stimulation compares to previous efforts. The results? Not baaad at all.
- Next, they tapped those brain cells to assess the pros and cons of cervical versus abdominal VNS for treating IBD:
- Intestinal inflammation was reduced the most with the least off-target cardiac and respiratory effects via abdominal VNS.
- What does this mean? Good news! Abdominal VNS did not cause any effects in heart rate, respiration rate or blood pressure.
The big picture: Huge efforts, including by the NIH, have gone into developing neural maps of the thoracic and abdominal cavities to support bioelectric implant tech. Call it a gut feeling, but with companies and researchers going at full force, it’s only a matter of time before T1D patients will be able to show off their electrifying abs.