Antidepressant found

A team of scientists has found that a drug used to treat depression can extend the lifespan of adult roundworms. Antidepressant drug mianserin can extend the lifespan of the nematode Caenorhabditis elegans by about 30 %.

The drug may act by mimicking the effects of caloric restriction. Studies indicate that lifespan extension by mianserin involves mechanisms associated with lifespan extension by dietary restriction.

The drug appears to act the same way in C. elegans andin humans: by blocking certain receptors for the neurotransmitter serotonin. Serotonin is a chemical that cells use to communicate, helping them regulate many functions.

It was a surprise to find that a drug used to treat depression in humans could extend lifespan in worms. The researchers found that in addition to inhibiting certain serotonin receptors in the worm, it also blocked receptors for another neurotransmitter, octopamine.

Serotonin and octopamine may complement one another in a physiological context. Mianserin had a much greater inhibitory effect on the serotonin receptor than the octopamine receptor. One possibility is that there is a dynamic equilibrium between serotonin and octopamine signaling and the drug tips the balance in the direction of octopamine signaling, producing a perceived, though not real, state of starvation that activates aging mechanisms downstream of dietary restriction.

Scientist focus on the effects of mianserin based on the results of a search through 88,000 chemicals for agents that extended the lifespan of nematodes and they found 115 chemicals. In follow-up studies of one chemical, they found four additional compounds that inhibit certain types of serotonin receptors in humans.

By identifying drugs that influence lifespan, it may be possible to home in on how those drugs act and contribute to a growing body of knowledge about the genetic mechanisms of aging. Other researchers work using molecular genetic approaches to identify genes involved in aging.

Other researchers work using molecular genetic approaches to identify genes involved in aging. They decided to take a chemical approach. By finding chemicals that enhance longevity, and then finding the targets of those chemicals, it may be possible to identify additional genes important in aging.