Worm study shows antidepressant may lengthen life

Worm study shows antidepressant may lengthen life
A petri dish containing C. elegans nemotodes, (round worms), is prepared for examination by scientists in this photo released on May 7, 2003. An antidepressant may help worms live longer by tricking the brain into thinking the body is starving, U.S. researchers reported on Wednesday. (NASA/Handout/Reuters)WASHINGTON (Reuters) - An antidepressant may help wormslive longer by tricking the brain into thinking the body isstarving, U.S. researchers reported on Wednesday.
The drug, called mianserin, extended the life span of thenematode Caenorhabditis elegans by about 30 percent, theresearchers reported in the journal Nature. They hope to findout if the same mechanism can help people live longer.
Three other compounds, including another antidepressant,have similar effects, said Michael Petrascheck of the FredHutchinson Cancer Research Center in Seattle. But thelife-extending benefits come at a cost.
"Weight gain and increased appetite seems to be one of theside effects. It is one of the reasons these are not suchpopular antidepressants," Petrascheck said in a telephoneinterview.
Many studies have shown that slightly starving certainanimals -- reducing how much they eat by about 30 percent --can cause them to live longer.
It is not entirely clear if this occurs in humans, butresearchers are keen to duplicate the beneficial effects ofcalorie restriction without the misery of going hungry.
Howard Hughes Medical Institute researcher Linda Buck andcolleagues were looking for drugs that might do this.
C. elegans is a roundworm, or nematode, much studiedbecause despite its tiny size, its biology is similar to thatof humans and other animals.
Buck's team did a random search through 88,000 differentdrug compounds to see if any of them happened to make C.elegans live longer.
They found four drugs that extended life span by 20 percentto 30 percent. The drug with the strongest effect wasmianserin, in a class of drugs known as tetracyclicantidepressants.
It blocks brain cell signaling by the neurotransmitter ormessage-carrying chemical serotonin, which is linked with moodand appetite.
The drug is used in Europe under several brand names,including Bolvidon, Norval and Tolvon but not usually in theUnited States. It can cause aplastic anemia and other effectson immune system cells.
Buck's team found that in addition to interfering withserotonin in the worm, it also blocked receptors for anotherneurotransmitter, octopamine.
They said some other research suggests that serotonin andoctopamine may complement one another -- with serotoninsignaling the presence of food and octopamine signalingstarvation.
Buck said it is possible that mianserin drug tips thebalance in the direction of octopamine, tricking the brain intothinking it has been starved.
Petrascheck said another antidepressant, mirtazapine, hadsimilar effects. An antihistamine and migraine drug calledcyproheptadine, as well as a compound not used in people calledmethiothepin also affected serotonin and extended worm lifespan.
They tested other popular antidepressants that affectserotonin and found they did not make the worms live longer.
He is worried that people will rush to take the drugs inthe hope of living longer."It is a stretch from a worm to a human being," Petraschecksaid.(Reporting by Maggie Fox, editing by Will Dunham and DavidWiessler)