Wednesday, July 15, 2009

Braking news

Talk about the fountain of youth! Ponce de Leon was looking in all the wrong places. Easter Island is where he should have been searching. And don't drink the water. Eat dirt.

The research report appears in the current Nature online: "Rapamycin fed late in life extends lifespan in genetically heterogeneous mice."
Inhibition of the TOR signalling pathway by genetic or pharmacological intervention extends lifespan in invertebrates, including yeast, nematodes and fruitflies; however, whether inhibition of mTOR signalling can extend lifespan in a mammalian species was unknown. Here we report that rapamycin, an inhibitor of the mTOR pathway, extends median and maximal lifespan of both male and female mice when fed beginning at 600 days of age. On the basis of age at 90% mortality, rapamycin led to an increase of 14% for females and 9% for males. Etc.
Rapamycin is produced by a bacterium that lives in the soil of Easter Island, also known as Rapa Nui, hence the name of the drug. It has been used as an immunosuppressor for transplants and in treating certain cancers. Discovering that it extends the lifetimes of mice came as something of an accident.

This is not the first drug that lets mice live longer, but it is the first that works on different strains of mice, male and female, and the first that works even if the drug is administered late in life (a 600 day-old mouse is equivalent to a 60 year-old human). The researchers don't know yet whether rapamycin puts the brakes on senescence, or just suppresses certain kinds of tumors.

By the way, note that the drug -- like most drugs -- is just carbon, oxygen, hydrogen and nitrogen, the usual stuff from the Tinker Toy set of life. It's all in the way the pieces are put together. Shape is the name of the game -- what latches onto what, lock and key. The diagram here is flat, but the molecule is three-dimensional and fits like a bug in a rug on the surface of a protein.

I can presently expect to live another five years, going by average male lifetimes. If I start sprinkling my cornflakes with Rapa Nui dirt maybe I can get another ten or twenty. But -- whoops! -- even if rapamycin works on humans, which it may or may not, it will be at least a dozen years before we see FDA approval, by which time I will be in the dirt myself. And if rapamycin works as an immunosuppressor, then -- well, it doesn't bear thinking about.

In the meantime, I will stick with resveratrol, an ingredient in red wine that may or may not give a modest bump in longevity. Even if I don't live longer, I will slip into oblivion with a silly inebriated smile.