NEW YORK, Oct 05 (Reuters Health) - If a tiny soil-dwelling worm is any guide, the secret to longevity may originate in certain signals from the brain, researchers suggest.

Scientists have long studied the worm, Caenorhabditis elegans, because certain genetic mutations can increase its life span many times over, according to Catherine A. Wolkow from Harvard Medical School in Boston, Massachusetts, and associates. But which particular cells are responsible for these life-extending signals has not been established.

The investigators conducted their experiments in normally long-lived worms whose life spans had been shortened by the removal of two genes--called daf-2 and age-1--from nerve, muscle and intestine cells. In an effort to determine how they work their life-prolonging magic, the researchers replaced the genes, one or the other of the various cell types.

Replacing either gene in nerve cells restored the long life span of worms, the authors report in the October 6th issue of Science. Restoring the gene activity in muscle or intestine cells overcame certain functional defects in the cells, but failed to increase the life span of the worm, Wolkow's team notes.

Further experiments showed that higher levels of the genes prolong life by activating certain pathways in nerve cells, the investigators observe.

The researchers propose that activation of these gene pathways controls the health of nerve cells that secrete a variety of hormonal signals, some of which regulate the life span of other tissues.

Because animals from worms to mammals probably share a common system for controlling life span, these findings suggest that the nervous system may act as a central regulator of animal longevity, Wolkow and colleagues conclude.

(Reuters Health)