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The rechargeable brain: Blood plasma from young mice improves old mice's memory and learning

The rechargeable brain: Blood plasma from young mice improves old mice's memory and learning

brain battery“Maybe Ponce de Leon should have considered becoming a vampire,” I noted here a few years ago. In a related Stanford Medicine article, I elaborated on that point (i.e. Dracula may have been on to something):

Count Dracula may have been bloodthirsty, but nobody ever called him stupid. If that practitioner of what you could call “the Transylvanian transfusion” knew then what we know now, it’s a good bet he was keeping his wits as sharp as his teeth by restricting his treats to victims under the age of 30.

I was referring then to an amazing discovery by Stanford brain-degeneration expert Tony Wyss-Coray, PhD, and his then-graduate student Saul Villeda, PhD, who now has his own lab at the University of California-San Francisco. They’d found that something in an old mouse’s blood could somehow exert an aging effect on the capabilities of a young mouse’s brain, and you know that ain’t good. They’d even pinpointed one specific substance (eotaxin) behind this effect, implying that inhibiting this naturally produced and sometimes very useful chemical’s nefarious action – or, if you’re a vampire, laying off the old juice and  getting your kicks from preteens when available – might be beneficial to aging brains.

But I was premature. While the dynamic duo had shown that old blood is bad for young brains and had also demonstrated that old mice’s brains produce more new nerve cells (presumably a good thing) once they’ve had continuous exposure to young mice’s blood, the researchers hadn’t yet definitively proven that the latter translated into improved intellectual performance.

This time out they’ve gone and done just that, in a study (subscription required) published online yesterday in Nature Medicine. First they conducted tricky, sophisticated experiments to show that when the old mice were continuously getting blood from young mice, an all-important region in a mouse’s brain (and yours) called the hippocampus perks up biochemically, anatomically and physiologically: It looks and acts more like a younger mouse’s hippocampus. That’s big, because the hippocampus is not only absolutely essential to the formation of new memories but also the first brain region to go when the early stirrings of impending dementia such as Alzheimer’s start subtly eroding brain function, long before outwardly observable symptoms appear.

Critically, when Wyss-Coray, Villeda and their comrades then administered a mousey IQ test (a standard battery of experiments measuring mice’s ability to learn and remember) to old mice who’d been injected with plasma (the cell-free part of blood) from healthy young mice, the little codgers far outperformed their peers who got crummy old-mouse plasma instead.

Slam dunk.

“This could have been done 20 years ago,” Wyss-Coray told me when I was assembling my release on this study. “You don’t need to know anything about how the brain works. You just give an old mouse young blood and see if the animal is smarter than before. It’s just that nobody did it.”

Previously: When brain’s trash collectors fall down on the job, neurodegeneration risk picks up, Brain police: Stem cells’ fecund daughters also boss other cells around, Old blood + young brain = old brain and Might immune response to viral infections slow birth of new nerve cells in brain?
Photo by Takashi Hososhima

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