The fountain of youth, at least for an aging brain, could be younger blood. A study from Stanford published in Nature recently found that by simply injecting blood from a young mouse into an old mouse had a "rejuvenation effect."
The reverse is also true. If old blood is injected into a young mouse, it has degenerative effects.
To arrive at the discovery, the researchers studied pairs of old and young mice that were literally joined at the hip. They used a technique called parabiosis, in which two mice are surgically joined together along the flank, which causes them to develop a shared circulatory system. The technique has been used to study the development of the blood system, and more recently has been used to investigate the effects of age by joining old and young mice.
According to Saul Villeda in Inside Stanford Medicine, a postdoctoral researcher in lead author Tony Wyss-Coray’s laboratory this procedure allowed researchers to "examine the effects of old mice’s blood on young mice’s brains, and vice versa."
Technology review goes on to report Wyss-Coray's findings:
. . .five weeks after creating these May-December pairings, "we found striking effects both on the young and old brains." The young mice had a reduction in the production of new neurons (neurogenesis), an increase in brain inflammation, and less activity in synapses connecting neurons.
The older mice, in contrast, had an increase in new neurons, less inflammation, and greater activity at synapses. "You could almost call this a rejuvenation effect," Wyss-Coray says.
According to Inside Standford Medicine, the researchers also circulating factors within blood that were associated with aging and degeneration of tissue. One of these was eotaxin, which is associated with allergic response and asthma. Researchers are now looking into if eotaxin is related to memory loss associated with Alzheimer’s disease, because they found younger mice injected with eotaxin performed poorly spatial-memory tests. If eventually research is able to block eotaxin, it could help lead to treatment for Alzheimers and some allergies.
The researchers are also looking for the factors in the younger blood that allow it to have rejuvenating effects.
[H/T Popular Science]