The old joke is, “We’ve cured cancer several times — in mice!”
But the trouble with our favorite lab animal is that they aren’t nearly as close to humans as we had hoped.
Researchers who are working on human longevity obviously need a model organism — they can’t keep their funding going for 100 years to see how a person dies. And other primates aren’t ideal, either; they’re also pretty long-lived and expensive to house, besides.
So what if you had a primate that was relatively short-lived, say 13 years tops, and quite small, say 100 grams, a bit bigger than a mouse? Behold the Mouse Lemur, Microcebus, the smallest member of the primate family.
In a pair of presentations Friday during the Duke Lemur Center’s 50th Anniversary scientific symposium, gerontologists Fabien Pifferi of the French national lab CNRS, and Steven Austad, chair of biology at the University of Alabama-Birmingham (UAB), made their arguments for how well “le microcèbe” might work in studying aging in humans.
Pifferi works at one of two mouse lemur breeding colonies in France, which is housed in an elegant old chateau in Brunoy, a suburb southeast of Paris. There, a 450-member breeding colony of grey mouse lemurs produces about 100 pups a year, and the scientists have devised many clever, non-invasive ways to test their physical and mental abilities as they age.
“It seems like their normal aging is very similar to humans,” Pifferi said. But about 20 percent of the tiny lemurs follow a different trajectory, marked by the formation of brain plaques, atrophy of the brain and cognitive declines. It’s not exactly Alzheimer’s disease, he said, but it may be a useful scientific model of human aging.
Aging, UAB’s Austad began, is already the number one health challenge on the planet and will remain so for the foreseeable future. We need a good research model to understand not just how to achieve longevity, but how to live healthy longer, he said.
Citing some early studies on using calorie restriction and rapamycin to increase longevity, Austad said mouse lemurs may be “a mid-way model between mice and humans.”
The CNRS colony at Brunoy tried to replicate a study on calorie restriction and longevity that had yielded mixed results in other animals. The mouse lemurs in the experimental condition thrived.
“I saw this colony last year,” Lemur Center Director Anne Yoder said. “The one remaining control animal was old and feeble and sort of pathetic. The four calorie-restricted animals were bouncing around, they were glossy.” Though suffering age-related blindness at that point, they were very much alive and frisky, Pifferi added.
“I think the mouse lemur is a great intermediate to do these sorts of studies,” Austad said.
But, as you may imagine, some members of the lemur community who have dedicated their lives to preserving rare and critically endangered lemurs might struggle with the idea of breeding up mouse lemurs to use as lab animals, even if the tests are non-invasive. Nobody asked hostile questions, but the discussion is sure to continue.
Post by Karl Leif Bates