Could you tell us about the vagus nerve and its function in the body?
The vagus nerve is the tenth cranial nerve. It is a paired nerve on the right and left. In the human body, each vagus nerve contains 80,000 to 100,000 nerve fibers; 80% are sensory, sending information to the brain. In Latin, Vagus means “wanderer,” an apropos name for this nerve, because it travels to the heart, lungs, spleen, liver, stomach, and intestines. The vagus network coordinates everyday bodily functions from digestion to breathing, and even immune function.
Vagus nerve activity varies from person to person, but it can be measured during an electrocardiogram to measure heart rate. The strength of the vagal response is known as vagal tone. Low vagal tone has been associated with many chronic inflammatory conditions, including rheumatoid arthritis.
Inflammation is a key component of the immune response, helping the body heal. However, in the case of excessive inflammation this response becomes harmful. In Dr. Kevin J. Tracey’s Laboratory of Biomedical Sciences at the Feinstein Institute for Medical Research we study the vagus nerve’s role in suppressing the inflammatory response. This work has led to the discovery of the “Inflammatory Reflex.” This reflex is mediated through the vagus nerve to stop damaging inflammation.
The inflammatory reflex is mediated through the vagus nerve to stop damaging inflammation.
Please could you describe what you did in your study?
In our study we looked at developing a standardized methodology for recording the electrical signals that are transmitted through the vagus nerve in mice. By recording this activity, we can begin to understand the language of the peripheral nervous system.
We investigated differences between electrodes used in recording vagus nerve activity, level of anesthesia, nutritional status, and strain effects on baseline vagus nerve activity. Several of these conditions have a significant effect on vagus nerve signals. However electrode configuration can make a significant difference in the quality of the recording.
Anesthetics affect neuronal function, and we demonstrated how isoflurane anesthesia can suppress vagus nerve signaling. Interestingly vagus nerve signals are also affected by feeding behavior. Administration of bacterial endotoxin caused a significant increase in vagus nerve activity. Our results outline a method that is both standardized and can be used to identify these short term electrical changes in vagus nerve activity.
How might these methods inform future research?
The method reported here have broad implications to inform future research on the vagus nerve. Mice are important in studying mechanisms, and our methodology can help us better understand the language of the nervous system in transgenic and knockout mice.
Signaling through the vagus nerve has links to cardiac function, pulmonary function, immune function, and metabolism. Understanding these signals can inform methods to use these signals to stimulate nerves to correct irregular signals.
What are the implications of this research in this field?
Previous work in our lab have mapped the inflammatory reflex. The new recording methods described here, in mice, give another layer to this understanding, as a wide variety of genetic mouse models are available. Taking this together this research with our prior work should accelerate the development of new detection methods, and treatments, for inflammatory disorders.
Dr. Silverman began his studies at Binghamton University, earning a Bachelor of Science degree in Anthropology in 2010 and a Master of Science degree in Biomedical Anthropology in 2012. He went on to earn his Doctor of Philosophy in the Molecular Basis of Medicine from the Donald and Barbra Zucker School of Medicine in 2018. His PhD work was done in Dr. Kevin J. Tracey’s Laboratory of Biomedical Sciences at the Feinstein Institute for Medical Research. There, Dr. Silverman studied the inflammatory reflex, focusing on understanding the role of sensory vagus nerve signaling in inflammation. He has over 10 publications in peer reviewed journals and has guest lectured at Binghamton University, as well as at the Elmezzi School for Molecular Medicine. His work has been presented at various international conferences, including the SHOCK Society meeting, the Society for Neuroscience, and the New York Academy of Sciences 13th Key Symposium on Bioelectronic Medicine- Technology Targeting Molecular Mechanisms.