9 Nervy Facts About the Vagus Nerve.
by Jordan Rosenfeld for Mental Floss
What happens in the vagus nerve, it turns out, doesn’t stay in the vagus nerve. The longest of the cranial nerves, the vagus nerve is so named because it “wanders” like a vagabond, sending out fibers from your brainstem to your visceral organs. The vagus nerve is literally the captain of your inner nerve center—the parasympathetic nervous system, to be specific. And like a good captain, it does a great job of overseeing a vast range of crucial functions, communicating nerve impulses to every organ in your body. New research has revealed that it may also be the missing link to treating chronic inflammation, and the beginning of an exciting new field of treatment that leaves medications behind. Here are nine facts about this powerful nerve bundle.
1. THE VAGUS NERVE PREVENTS INFLAMMATION.
With a vast network of fibers stationed like spies around all your organs, when the vagus nerve gets wind of the hallmarks of inflammation—cytokines or the inflammatory substance tumor necrosis factor (TNF)—it alerts the brain and elicits anti-inflammatory neurotransmitters via the cholinergic anti-inflammatory pathway. A certain amount of inflammation after injury or illness is normal. But an overabundance is linked to many diseases and conditions, from sepsis to the autoimmune condition rheumatoid arthritis.
2. IT HELPS YOU MAKE MEMORIES.
A University of Virginia study showed success in strengthening memory in rats by stimulating the vagus nerve, which releases the neurotransmitter norepinephrine into the amygdala, consolidating memories. Related studies were done on humans, opening promising treatments for conditions like Alzheimer’s disease.
3. IT HELPS YOU BREATHE.
The neurotransmitter acetylcholine, elicited by the vagus nerve, literally gives you the breath of life by telling your lungs to breathe. It’s one of the reasons that botox—often used cosmetically—can be potentially dangerous, because it interrupts your acetylcholine production. You can, however, also manually stimulate your vagus nerve by doing abdominal breathing or holding your breath for four to eight counts.
4. IT’S INTIMATELY INVOLVED WITH YOUR HEART.
The vagus nerve is responsible for controlling the heart rate via electrical impulses to the sinoatrial node of the heart, where acetylcholine release slows the pulse. The way doctors determine the “tone” or “strength” of your vagus nerve (and your cardiac health) is by measuring the time between your individual heart beats, and then plotting this on a chart over time. This is your “heart rate variability.”
5. IT INITIATES YOUR BODY’S RELAXATION RESPONSE.
When your ever-vigilant sympathetic nervous system revs up the fight or flight responses—pouring the stress hormone cortisol and adrenaline into your body—the vagus nerve tells your body to chill out by releasing acetylcholine. Its tendrils extend to many organs, acting like fiberoptic cables that send instructions to release enzymes and proteins like prolactin, vasopressin, and oxytocin, which calm you down. People with a stronger vagus response may be more likely to recover more quickly after stress, injury, or illness.
6. IT TRANSLATES BETWEEN YOUR GUT AND YOUR BRAIN.
Your gut uses the vagus nerve like a walkie-talkie to tell your brain how you’re feeling via electric impulses called “action potentials". Your gut feelings are very real.
7. OVERSTIMULATION OF THE VAGUS NERVE IS THE MOST COMMON CAUSE OF FAINTING.
If you tremble or get queasy at the sight of blood or while getting a flu shot, you’re not weak; you’re experiencing “vagal syncope.” Your body, responding to stress, overstimulates the vagus nerve, causing your blood pressure and heart rate to drop. During extreme syncope, blood flow is restricted to your brain, and you lose consciousness. But most of the time you just have to sit or lie down for the symptoms to subside.
8. ELECTRIC STIMULATION OF THE VAGUS NERVE REDUCES INFLAMMATION AND MAY INHIBIT IT ALTOGETHER.
Truly breaking new medical ground, neurosurgeon Kevin Tracey was the first to prove that stimulating the vagus nerve can significantly reduce inflammation. Results on rats were so successful, he reproduced the experiment in humans with stunning results. The creation of implants to stimulate the vagus nerve via electronic implants showed a drastic reduction, and even remission, in rheumatoid arthritis—which has no known cure and is often treated with the toxic cancer drug methotraxate—hemorrhagic shock, and other equally serious inflammatory syndromes.
9. VAGUS NERVE STIMULATION HAS CREATED A NEW FIELD OF MEDICINE.
Spurred on by the success of vagal nerve stimulation to treat inflammation and epilepsy, a burgeoning field of medical study, known as “bioelectronics,” may be the future of medicine. Using implants that deliver electric impulses to various body parts, scientists and doctors hope to treat illness with fewer medications and fewer side effects.