Tiny contractile cells surrounding the brain’s capillaries called pericytes regulate vascular blood flow and maintain blood-brain barrier integrity. Pericytes detach from the blood vessels in aging, driving the pathophysiology of neurological dysfunction, vascular dementia, and stroke. A recent study in rodents shows that pericytes also play roles in long-term memory formation.

Researchers measured the amount of insulin-like growth factor 2 (IGF2) produced by various cells in the hippocampus of rodents. IGF2, a peptide hormone produced in multiple tissues, regulates growth during fetal development and participates in the cell cycle throughout the lifespan. After determining that pericytes contributed the greatest amount of hippocampal IGF2, they assessed learning’s influence on IGF2.

They found that learning increased pericyte IGF2 production in the hippocampus, especially in the dentate gyrus, a highly vascularized area responsible for episodic memory – long-term memory that involves conscious recollection of previous experiences and their associated contexts, such as sounds and smells. Animals lacking the ability to produce IGF2 in their pericytes exhibited poor learning and memory.

The detachment and loss of pericytes play a crucial role in the progression of cerebral small vessel disease and neurodegenerative disorders that involve blood-brain barrier dysfunction. These specialized endothelial cells envelop a significant portion, up to 80 percent, of the brain capillary surface area in the cortex and hippocampus of the human brain. They also enwrap the tiniest vessels constituting the blood-brain barrier.

Exercise mitigates the proinflammatory state that drives pericyte loss in aging, possibly providing a mechanism for exercise’s memory-enhancing effects. Learn more about links between exercise, pericytes, and brain health in this episode featuring Dr. Axel Montagne.

• Read study abstract.