The Importance of Insulin Action in the Brain for the Immune System During Physical Activity

The Importance of Insulin Action in the Brain for the Immune System During Physical Activity

The goal of this clinical trial is to clarify the interaction of central insulin action and physical activity with the immune system.

Therefore, participants will undergo bicycle spiroergometer tests. This approach will be compared between days with insulin delivery to the brain as nasal spray and days with placebo spray.

This research project aims to investigate if the brain insulin action regulates the immune system via the autonomous nervous system during physical activity.

Therefore, insulin action in the brain will be introduced by application of insulin as nasal spray (on one day) versus carrier solution as placebo nasal spray (on another day) in a randomized, blinded fashion. Spray administration will be performed 30 minutes before a 60 min bicycle spiroergometer test at 70 % VO2max that will introduce a postprandial state. On placebo day, the known spillover of tiny amounts of nasal insulin into the systemic circulation will be mimicked by an appropriate i.v. insulin bolus. Using this approach, brain-derived regulation of the immune system including the stimulation of immune cells via cytokines, physical performance, activity of the autonomous nervous system and gene-expression of leukocytes will be examined.

Inclusion Criteria:

• BMI < 24 kg/m2
• no known primary diseases
• hormonal contraception with a single-phase preparation

Exclusion Criteria:

• Alcohol or drug abuse
• Smoking
• At screening: Hb < 12 g/dl for women and Hb < 14 g/dl for men
• Any (clinical) condition that would endanger participant's safety or question scientific success according to a physician's opinion.