Young blood really does rejuvenate the brain, at least in mice, raising hopes that molecules in the blood may be identified to do the same for humans, according to a study stemming from the ongoing research of a young UC San Francisco scientist, Saul Villeda, PhD.

The research, on which Villeda collaborated with scientists at Stanford University, identified anatomical, molecular and biochemical evidence of cognitive improvements and other forms of rejuvenation in old mice when they were connected to the circulatory system of young ones. Results were published online in Nature Medicine on May 4.

In experiments led by Saul Villeda, PhD, old mice that received the blood of young micehad increased activation of Creb, aprotein that is a master regulator of nerve growth in the hippocampus. The hippocampus is a brain region crucial for learning and memory. The deeper staining in the image on the right shows the increased Creb activation as a result of exposure to young blood.

Credit: Nature Medicine

Anatomically, it was clear that these mice formed more structural and functional connections between neurons, or nerve cells, while they also turned on more genes associated with the formation of new nerve connections.

Furthermore, the researchers found that a protein called Creb became more activated in the brain region known as the hippocampus, and that this increased activity was associated with the anatomical and cognitive improvements the team observed.

We know that something in the young blood leads to Creb activation, and the Creb is a master regulator of gene activity in the brain that is associated with the formation of new connections between neurons underlying learning and memory, Villeda said, adding that Creb activation is known to decrease in both normal human aging and in Alzheimers disease.

In the behavioral experiments, old mice were injected with either old or young blood. Cognitively, old mice with young blood coursing through their veins performed better. When immersed in water, they were better able to recall the location of a submerged platform and climb onto it. In a separate, fear-conditioning exercise, they responded more quickly to stimuli normally perceived as threatening, a behavior important for survival.

Identifying and getting rid of aging factors in old blood, or supplying youthful factors from young blood, might both be worthwhile strategies to combat aging, Villeda says. But dont try injecting yourself with saved samples of your young blood at home just yet.

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