Ninety-five percent of all lab animals are rodents. In addition to being relatively cheap, docile animals with short life spans (making studies that span several generations much easier to conduct), the genetic, biological and behavioral characteristics of mice are very similar to humans. Mice share 90% of their genes with us, which means researchers can effectively replicate symptoms of common conditions in the small animals in the service of study. A great start certainly, but the human body is nothing if not complex.
However successful rodent trials prove to be, there will invariably be several years and further tests that stand between them and a perfect human translation. Rodents are nonetheless integral first steps and they have been for many years, inspiring the use of penicillin, vaccines and providing key insights into the nature of viruses.
This month, new finds featured in the journal Cell Metabolism, utilized mice to unpack the enigmatic aging process, one enzyme at a time.
An unexpected biomarker
After researchers dosed a crop of elderly mice with an enzyme from the blood of young mice, the old mice lived 16% longer than they would have otherwise, in addition to exhibiting youthful features. The report highlights a molecule called Nicotinamide Adenine Dinucleotide (NAD). NAD is a cofactor found in living cells, responsible for a series of reactions and gene expression. Previously conducted research has shown that this molecule declines in humans as we get older.
The enzyme called extracellular nicotinamide phosphoribosyltransferase, or eNAMPT is vital in the creation of NAD molecules in both mice and human species. The more eNAMPT in mice observed the new study, the longer the mice lived. Levels of eNAMPT in mice fat tissue dropped by 33% by the time they reached six months of age.
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The scientists injected blood components of eNAMPT from young to middle-aged mice aged between four and 12 months into the bodies of old ones aged 26 months, documenting miraculous results. The cells in the elderly mice eyes responded to light much better than they did before, they became better at producing insulin, they ran for longer on their exercise wheels, their sleeping patterns improved and they even evidenced enhancements to their cognition via a series of successful memory tests.
“These are old mice with no special genetic modifications, and when supplemented with eNAMPT, their wheel-running behaviors, sleep patterns and physical appearance — thicker, shinier fur, for example — resemble that of young mice,” commented Dr. Shin-ichiro Imai, who is a professor of developmental biology at Washington University School of Medicine, as well as the senior author of the new study to Newsweek.
eNAMPT works exactly the same in human blood circulation as it does in mice, so Imai and his team are anticipating similar results. That isn’t to say it will categorically yield the exact same results, but the findings warrant promoting eNAMPT has a key biomarker of the aging process for both species