Intense exercise alters how hormonal signals are transported to the brain. Digest
Exercise affects multiple physiological processes regulated by hormones, including stress responses and energy balance. Yet scientists still do not fully understand how some hormone precursors travel through the bloodstream during these demanding moments. A new study explored how vigorous exercise changes the way a major hormone precursor, called proopiomelanocortin (POMC), travels through the bloodstream and helps it reach sensitive tissues like the brain.
You just missed this in your inbox
Every other week our Premium Members received this exact study plus Rhonda's practical commentary and 8+ other hand-picked papers.
The study involved 15 healthy, endurance-trained adults who completed a 50-minute treadmill run at high intensity. The researchers focused on whether exercise encourages POMC to attach to small extracellular vesicles (often abbreviated to sEVs). These are microscopic, membrane-wrapped particles released by cells that can carry biological signals between tissues. They also tested the effect of this attachment on how easily POMC crosses cellular barriers.
- Most circulating POMC remained intact rather than being processed into smaller hormones such as ACTH or β-endorphin.
- Total POMC levels in blood also did not rise with exercise, nor did the number or size of sEVs. However, about four times more POMC was found attached to sEVs, and this shift partly reversed during recovery.
- Lab tests showed that making blood slightly more acidic, at levels similar to those seen during hard exercise, increased how much POMC attached to sEVs.
- POMC bound to sEVs crossed layers of endothelial cells (cells that line blood vessels) and a laboratory model of the blood–brain barrier more efficiently than free POMC.
- After crossing barriers in lab models, vesicle-bound POMC produced a measurable response in test cells.
To explain these results, the researchers turned to molecular modeling. Their analyses suggest that lower blood pH (higher acidity) causes a subtle shape change in POMC, exposing a region that binds more easily to receptors embedded in vesicle membranes. In other words, exercise-related acidity appears to make POMC better suited to latch onto sEVs, which then act as transport vehicles.
The study was small and focused on fit adults, and many experiments used laboratory models rather than living tissues. Still, the findings point to a previously unrecognized way exercise may fine-tune hormonal signaling. If confirmed, this vesicle-based transport system could help explain how physical stress rapidly reshapes communication between blood, immune cells, and the brain. In this clip, I discuss how vigorous exercise improves heart and brain health, enhances focus, and provides anti-cancer benefits.