Old Brains Prefer Young Blood

A paper published today in Nature finds that when younger mice are exposed to the blood of older mice, their brain cells behave more like those found in aging brains, and vice versa. The researchers who carried out the work also uncovered chemical signals in aged blood that can dampen the growth of new brain cells, suggesting that the decline in brain function with age could be caused in part by blood-borne factors rather than an intrinsic failure of brain cells. _TechnologyReview

It has been previously found that young blood can reverse certain signs of aging in the circulatory systems of old mice. Now there is evidence that young blood can help rejuvenate old brains.

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.

Lead author Tony Wyss-Coray, a neuroscientist at Stanford University, says that 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.

...To see whether the effect could influence behavior, they injected, in separate experiments, young mice with plasma from older mice and vice versa, and found that old plasma impaired the younger animals' ability to perform learning and memory tasks, whereas young plasma improved the abilities of older mice.

Blood cells from one mouse cannot travel into the brain of the other because of the blood-brain barrier, so the team concluded that free-floating molecules in the blood, capable of passing through, must be responsible for the effects. By comparing more than 60 chemokines—chemical messengers secreted by cells that circulate in the blood—the researchers identified several associated with the detrimental effect of old blood. Administering one of these chemicals, called CCL11, to young mice dampened neurogenesis and impaired learning and memory. CCL11 has been studied for its role in allergies and asthma, but it's not clear how it influences neurons. _TechnologyReview

Does this mean that those of us who wish to stay young will have to prey on our young like vampires, sucking their life's blood for our own sustenance? No. For we are learning how to take our old cells and make them young again, in vitro -- in the test tube. The goal is to do the same thing, only better, and in vivo.

Such cellular rejuvenation treatments are likely to prove excellent stopgap methods of anti-aging, with significant -- but limited -- effects. The lifespans we live will be lived as younger, more vital monkey-men. And that is worth a very great deal.

But if we wish to live significantly longer lives, at significantly higher levels of awareness, intellect, and invention, we will need to go deeper than cellular replacement and humoral replacement therapies of this type.

Taken from an article published at Al Fin Longevity

In Chernobyl, 60 Year Old Men Appear "Not a Day Over 30"

18March2011 Brian Wang has more on this story

"Radiation is good for you," one of them tells me. "Every year I get younger," says another. And another: "I work here so when I come home glowing my wife will think I'm a god."

A particularly hearty-looking man who works as a janitor asks me, "How old do you think I am?"

"Sixty," he answers himself....he looks not a day past 30. _Outside

As of January of this year, Chernobyl is now open to tourism. Over most of what is now the Chernobyl wildlife haven, radiation levels have returned near normal. The wild animal population is thriving, and the people there do not seem to be doing so badly themselves. Particularly so long as they have an ample supply of homemade vodka.

Residents of Chernobyl are not the only ones who claim health benefits from low dose exposure to ionizing radiation. Skim through the research regarding "radiation hormesis" referenced here and here, and you may begin to develop a bit of healthy skepticism toward the "zero tolerance policy" of modern environmental protection law toward low level radiation.

More on hormesis:

Hormesis is the term used to describe biological phenomena that are often adverse or detrimental but become beneficial when applied at low levels. The concept of biological hormesis is as important as that of homeostasis for the survival of the organism. The basic biological trait is the organism�s ability to resist and adapt appropriately to both internal and external stresses, and the hallmark of aging is the organism�s inability to withstand stress. The hormetic phenomenon in aging is characterized as beneficial responses to stress through the physiological adaptations, as exemplified in lifespan extension by irradiation and calorie restriction. Thus, hormesis in aging is the biological adaptive function to resist or blunt the age-related deleteriousness. Such a remarkable biological hormetic effect was shown experimentally by exposing mice to a low dose of gamma irradiation, which extended the lifespan of mice rather than shortening by turmorigenesis. The plausible explanation on this interesting radiation hormesis is that the irradiated mice were able to resist better, because the mild radiation itself is the most effective factor in conditioning for the activation of adaptation. In response to stress, an organism is expected to go through three distinct phases: alarm reaction, resistance phase, and exhaustion phase. According this schema, the adaptability can be developed during the resistance period. This notion is in line with the evolutionary view on the survival for the fittest theory, for which the only possible way to attain the survivability is through the organism�s metabolic and defensive adaptation to deleterious stress. _InnoVita

More on hormesis and ageing from an abstract in Ageing Research Reviews:

Hormesis in aging is represented by mild stress-induced stimulation of protective mechanisms in cells and organisms resulting in biologically beneficial effects. Single or multiple exposure to low doses of otherwise harmful agents, such as irradiation, food limitation, heat stress, hypergravity, reactive oxygen species and other free radicals have a variety of anti-aging and longevity-extending hormetic effects. Detailed molecular mechanisms that bring about the hormetic effects are being increasingly understood, and comprise a cascade of stress response and other pathways of maintenance and repair. Although the extent of immediate hormetic effects after exposure to a particular stress may only be moderate, the chain of events following initial hormesis leads to biologically amplified effects that are much larger, synergistic and pleiotropic. A consequence of hormetic amplification is an increase in the homeodynamic space of a living system in terms of increased defence capacity and reduced load of damaged macromolecules. Hormetic strengthening of the homeodynamic space provides wider margins for metabolic fluctuation, stress tolerance, adaptation and survival. Hormesis thus counter-balances the progressive shrinkage of the homeodynamic space, which is the ultimate cause of aging, diseases and death. Healthy aging may be achieved by hormesis through mild and periodic, but not severe or chronic, physical and mental challenges, and by the use of nutritional hormesis incorporating mild stress-inducing molecules called hormetins. The established scientific foundations of hormesis are ready to pave the way for new and effective approaches in aging research and intervention. _ARR

How much is too much, when it comes to radiation? That is difficult to say, at lower doses. Certainly if it is possible to build resistance against radiation and other sources of normal wear and tear, wouldn't most people want to do so?

A dangerous dose is hard to pin down. Worldwide, for most people, those daily microrems add up to about 360 millirems per year. Scientists agree that humans can safely handle 1,000 a year. Astronauts on the International Space Station receive 18,000 millirems of cosmic radiation over six months—but it's once in a lifetime, so it's seen as an acceptable, voluntary risk. But edge that up to 30,000 millirems and you're looking at what caused increased cancer rates among the blast survivors of Hiroshima and Nagasaki. And yet animals can handle even more than this: large mammals and birds are generally safe with 36,000 per year, small ones with even higher doses, and reptiles with higher still. The more complex the animal, the more sensitive it is. _Outside

Of course, animals spend more time outside under the ionizing radiation of the sun, than most modern humans. Perhaps the natural radiation protection exhibited by animals is a manifestation of hormesis?

As long as government-sanctioned science shies away from the topic of "safe levels of low level radiation," we may find it difficult to learn about this topic. With government becoming the largest financier of scientific research, human science is falling into something of a rut. Government bureaucracies are by nature conservative and self-serving. Naturally the science which such bureaucracies are willing to finance and publish, will be the kind of science which justifies the existence and mission of such bureaucracies. They're the government. They're here to help you. Or else.

How will we all survive after the house of cards crashes down? If there is life after a Chernobyl apocalypse, perhaps there could even be life after mega-government breakdown? It may be time for individuals to begin planning for interesting times ahead.

See you in Chernobyl?