Effect of Transcutaneous Auricular Vagus Nerve Stimulation (taVNS) on Plasma Insulin Levels

Summary

The vagus or vagal nerve is a nerve that sends signals from the brain to other parts of the body to control involuntary functionm, including stomach function, and it is important to the regulation of insulin, C-peptide, and glucose levels. The purpose of this study is to evaluate whether electrically stimulating the nerve around the external ear will also stimulate the internal vagus nerve and influence the levels of insulin, C-peptide, and glucose. If it does, investigators hope that this will help innovate treatment of patients with nausea, vomiting, and disordered stomach function, and patients with diabetes.

Detailed Description

Healthy volunteer subjects will be recruited for this project, which will be completed at a up to 2 study visits. Prior to each visit, participants will be asked not to eat or drink anything (except a small amount of water to take medications) for 8-10 hours. When participants arrive to Study Visit 1, they will be asked to lie in a supine position and will be fitted with: * ECG electrodes, placed on the chest, arms/legs for electrocardiogram (ECG) recordings and behind each ear and just below the jaw on each side to record vagal nerve activity * a butterfly needle catether for blood sample collections. After the ECG electrodes are placed and the butterfly needle catheter is inserted, the first of 4 blood samples will be collected. The TENS unit clip will then be placed (after cleaning the left ear with an alcohol wipe) and a 20 minute baseline recording will be made, followed by the collection of a second blood sample. Participants will then undergo their randomly assigned experimental condition (either active stimulation delivered via the TENS device, or no stimulation) for 40 minutes. At the end of the experimental period, a third blood sample is collected and the TENS device is turned off (for participants in the active stimulation group). Participants will then continue to lie on their back for an additional 20 minutes of recovery, after which the fourth and final blood sample is collected. The TENS clip is then removed and the study visit is complete. Continuous vagal nerve and ECG recordings are obtained during the baseline, experimental, and recovery periods. Participants will be asked if they wish to return for a second study visit, at which no TENS clip will be placed but the remaining Visit 1 procedures will be repeated.

Eligibility Criteria

Interventions