Clues to Why Exercise Helps You Live a Longer, Healthier Life

Researchers at the Howard Hughes Medical Institute have uncovered clues to suggest why living a healthier lifestyle will help you live longer. The answer, they say, is less insulin in the brain.

In their experiments, the researchers sought to understand the role of the insulin-like signaling pathway in extending lifespan. This pathway governs growth and metabolic processes in cells throughout the body. The pathway is activated when insulin and insulin-like growth factor-1 switch on proteins inside the cell called insulin receptor substrates (Irs).

In earlier work, the researchers had found that knocking out both copies of one of the Irs genes, Irs2, in mice reduces brain growth and produces diabetes due to pancreatic beta cell failure. However, in the new study, when the researchers knocked out only one copy of the gene, they found the mice lived 18 percent longer than normal mice.

Because reducing insulin-like signaling in the neurons of roundworms and fruitflies extends their lifespan, the researchers decided to examine what would happen when they knocked out one or both copies of the Irs2 gene only in the brains of mice.

Mice lacking one copy of the Irs2 gene in brain cells also showed an 18 percent longer lifespan, and the near complete deletion of brain Irs2 had a similar effect. “What's more, the animals lived longer, even though they had characteristics that should shorten their lives—such as being overweight and having higher insulin levels in the blood,” said Morris F. White, an investigator for HHMI.

However, both sets of Irs2 knockout mice exhibited other characteristics that marked them as healthier, said White. They were more active as they aged, and their glucose metabolism resembled that of younger mice. The researchers also found that after eating, their brains showed higher levels of superoxide dismutase, an antioxidant enzyme that protects cells from damage by highly reactive chemicals called free radicals.

White and his colleagues are planning their next studies to better understand how healthy aging and lifespan are coordinated by Irs2 signaling pathways in the body and the brain. White speculated that the insulin-like signaling pathway in the brain might promote age-related brain diseases.

Personally, I'll be most interested in seeing how this work meshes with the work being done on Sirtuin. Calorie Restriction methods have not been shown to be effective in humans yet, but there's no reason to think that they won't be. The research on brain insulin, on the other hand, is something that will have to be watched fairly closely. While mice may make an interesting model for early-stage testing, their brains are not that similar to ours and any type of alteration being done on the brain could have effects that would not be obvious in a mouse model.

Defending Science

As you well know by now, I am in favor of the responsible advancement of science and technology. But not everyone, it seems, shares my opinion. In particular, the current government administration in this country seems to put politics before scientific and technological advancement, and for that reason, the people at Defend Science are on the march.

From their latest e-mail:

No doubt you have heard of the recent testimony of former Surgeon General Richard Carmona to the House Oversight and Government Reform Committee on July 10, 2007. Dr. Carmona’s testimony was stunning exposure of the Bush Administration’s willingness to deny scientific truth in the pursuit of a political agenda. Defend Science is calling on people to voice their opinion to newspapers throughout the country with letters expressing outrage at not only the overt politicization of science to an unprecedented level, but its outright denial. As the Defend Science statement says, we must all “insist on an atmosphere where scientists are allowed to seek the truth, even when the truth conflicts with the views and policies of those in power... where science education and the popularization of the scientific method are valued...”

In his testimony Dr. Carmona stated that the discussion in the Bush Administration around stem cell research was “devoid of science” and that the policy around sex education was to “preach abstinence which I felt was scientifically incorrect.” He further revealed that his speeches were vetted for political content and his attempt to educate the public about issues ranging from stem cells to sex education “blocked at every turn.” In each case, Dr. Carmona indicated that science is denied in the face of political, ideological and theological considerations.

Check out http://www.defendscience.org/surgeon_general.html for media coverage and links to excerpts from the testimony, and add your voice to the discussion. Dr. Carmona’s testimony alone is an indictment of the Bush Administration’s public health policy, but it also points to the broader issue of why we need to defend science. There is an unrelenting assault on people's access to scientific knowledge, to the scientific method and approach to knowing about the world, to the scientific spirit. The more letters we write to local papers exposing and opposing this agenda the bigger the impact on the public discourse around the critical issue of defending science we will have.

We at Defend Science would appreciate your help in keeping us abreast of this effort. Please send us copies of your letters (send to multiple publications if you can), any posting you make to blogs or comment sections, and similar public outlets--and be sure to identify where you submitted the pieces. And let us know if your letter is published!

Hey Buddy, Wanna Be an Astronomer?

Thanks to Phil Plait for turning me onto a new opportunity for amateurs like me (and, presumably, you) to participate in scientific research. In the past several years, advanced astronomical telescopes have collected vast amounts of data--more than can be reasonably processed by astronomers. The solution, of course, was to use advanced pattern-recognition algorithms to analyze the images.

That introduced a secondary problem... namely, that the most advanced pattern-recognition algorithms available today are still not advanced enough to catch everything. That's where amateurs, like me (and, presumably, you) come in. From the GalaxyZoo website:

Why do we need you?
The simple answer is that the human brain is much better at recognising patterns than a computer can ever be [EDITOR'S NOTE: I don't think this is acutally true... eventually computers will surpass our ability to recognize patterns, but certainly not anytime soon.] . Any computer program we write to sort our galaxies into categories would do a reasonable job, but it would also inevitably throw out the unusual, the weird and the wonderful. To rescue these interesting systems which have a story to tell, we need you.

The site includes a tutorial to explain what they're looking for and how to get started, and once you get used to it, it's pretty fun. After that, there's a trial that challenges you to identify galaxies, and if you get at least eight correct (out of 15) you'll be able to get started classifying galaxies and contributing to the advancement of our understanding of the universe.

Happy hunting!