According to a study published on July 8 in the journal Nature, a natural compound used as an immunosuppressant in organ-transplant patients has been found to extend life in mice. Aging mice that were given the substance, rapamycin, lived significantly longer than mice that didn’t get the drug: females that received rapamycin were 13% older at death and males 9% older.
Researchers had intended to study mice from early ages but were stymied by technical difficulties, so scientists weren’t sure they could expect clear results. However, even administered late in life, rapamycin delayed the deaths of the longest-lived male mice by 101 days and by 151 days in the longest-lived females — the equivalent of about 13 years on average in humans — compared with mice with no treatment. In terms of life expectancy when treatment began (or average remaining lifespan when the mice were 600 days old), that translates to an increase of 38% in female mice and 28% in males.
Although the results are untested in humans, they do suggest that aging could be slowed by drugs. Exactly how rapamycin works is “still an open question,” But researcher were prompted to test the aging effects of rapamycin, which was discovered in Easter Island soil samples about 40 years ago, after noting that the compound appeared to affect cell growth in lab animals in much the same way as calorie-restricted diets, which also appear to extend life. It’s this cellular efficiency, perhaps, that delays aging and helps preserve animals’ good health. The findings suggest that rapamycin does not affect or prevent any one disease specifically — the mice in the study died of various causes, with no real difference between mice that received rapamycin and those that didn’t — but rather that it slows aging overall.
As agents for extending life, other drugs may be further along in the pipeline — resveratrol, for one, which has also prolonged life in lab mice. But the new finding by researchers more clearly identifies the [target of rapamycin] pathway as important across species. It may guide researchers to target different proteins in the same pathway. “If those proteins react the same way to extend lifespan, then we might be able to get rid of unwanted side effects,” researcher said.
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