Friday February 28 2014
A wonder drug for a bright future?
The Daily Telegraph and Daily Express both carry headlines about how a “pill” to help humans live longer could be on the cards. Though while the substance being studied shows promise, the research only involved mice.
Researchers were looking at a chemical called SRT1720 which activates a particular protein called Sirtuin 1 (SIRT1). Previous research has demonstrated that activating SIRT1 can have health benefits in various organisms, and it has been proposed as an anti-ageing protein.
This study focused on comparing the lifespan, health and diseases of mice fed the same diet, but with or without the addition of a SRT1720.
Overall they found mice fed a normal diet but with the supplement had a longer natural lifespan on average (about five weeks longer).
During their lifetime, additional tests also suggested they had improved muscle function and coordination, improved metabolism, improved glucose tolerance, decreased body fat and cholesterol.
All in all this suggests that giving the mice this supplement could protect them from the equivalent of metabolic syndrome, a series of risk factors associated with conditions such as heart disease and type 2 diabetes.
This is interesting research but as it only involved mice, the normal caveats regarding animal studies apply. Importantly, researchers did not look at whether SIRT1 may cause side effects or complications. So it is currently unclear whether SIRT1 would be safe in humans, let alone effective.
The SIRT1 protein could be a possible candidate in the quest to find an “elixir of life” but these are very early days.
Where did the story come from?
The study was carried out by researchers from the US National Institute of Aging part of the National Institutes of Health and other research institutions in the US and Australia. Funding was provided by the National Institute on Aging, National Institutes of Health. Some of the researchers involved in the study are employed by Sirtis, a company with a declared commercial interest in developing a SIRT1 activator.
The study was published in the peer reviewed scientific journal Cell. This article was open-access (unlike most of Cell’s content), meaning that it can be accessed for free from the journal’s website.
The media is rather premature in concluding from this early stage research in mice that a life-prolonging pill could be on the cards anytime soon. Though it is true that this research has findings worthy of further study.
Also, unlike the Telegraph, the fact that the research is in mice isn’t apparent in the Daily Express article.
What kind of research was this?
This was an animal study in mice which centred on a chemical called SRT1720 which is thought to activate a particular protein, Sirtuin 1 (SIRT1). SIRT1 is known to play an important role in maintaining homeostatic balance (keeping the various systems of the body on a “stable footing”).
Previous research has demonstrated that SIRT1 activation can have health benefits in various organisms, and it has been proposed as an anti-ageing protein. It has been suggested that pharmacological interventions that aim to increase SIRT1 activity could slow the onset of ageing as well as delaying the onset of diseases associated with ageing – such as heart disease.
Prior study has shown that treating mice with small molecule activators of SIRT1 such as SRT1720 can balance the detrimental effects of a high-fat diet. This is achieved by improving insulin sensitivity and preventing oxidative metabolism (damage at the cellular level).
However, most of the previous research in mice has focused on reversing the effects of a poor diet.
This research aimed to see whether activating SIRT1 using SRT1720 can improve health and lifespan in mice fed a normal diet.
What did the research involve?
The researchers used 28-week-old male mice separated into four groups of 100. They were fed on four diets:
- standard diet (carbohydrate: protein: fat ratio of 64:19:17 percent of kcal)
- the standard diet supplemented with the SRT1 activator molecule – SRT1720
- high-fat diet (carbohydrate: protein: fat ratio of 16:23:61)
- the high fat diet supplemented with SRT1720
The SRT1720 supplements were included in the diets at an approximate daily dose of 100mg/kg body weight. The mice had their body weight and food intake monitored biweekly.
Mice received various tests during the study, including having their metabolic rate measured after they had been on the diets for about six months. And then their body fat mass and glucose tolerance measured when they had been on the diets for almost a year.
They also had exercise testing when between one and two years of age. The animals lived out their lifespan and then their organs were examined after death.
What were the basic results?
The researchers found that survival between the two groups of mice fed the standard diet was significantly different – average lifespan was increased by 8.8% (around five weeks) when mice were given the SRT1720 supplement. In the high fat mice, survival was significantly lower, but still the SRT1720 supplement increased lifespan by 21.7% (around 22 weeks). Overall statistical analyses showed that the supplement significantly reduced the risk of death.
Also, the SRT1720 supplement decreased the body weight of both the standard diet and high fat diet mice, compared with their counterparts on the same diets, despite the fact that the mice were consuming the same number of calories.
However, the supplement only decreased percentage of body fat in those mice on the standard diet; in those on the high fat diet the supplement had no effect on fat mass percentage.
In the standard diet mice, the SRT1720 supplement also had beneficial effects on their metabolism and lead to a noticeably improved performance on an activity test. This suggests they had better balance and muscle function, though a similar effect was not seen in the high fat diet.
There was also some suggestion that the supplement improved insulin sensitivity and glucose balance, and also lowered blood cholesterol in mice fed the standard diet. Cataract formation in the eyes was also reduced.
There was no difference in the number of diseases seen on autopsy examination after death between animals given the supplement and those not. However, the researchers say that as the average age at autopsy was around 10 weeks later in those given the supplements, it could be that SRT1720 delays the onset of diseases allowing mice to live a longer life without disease.
How did the researchers interpret the results?
The researchers conclude that their results show that supplementation with a molecule that activates SRT1 improves health and extends lifespan in mice maintained on a standard diet. They say their work “highlights the importance of examining the therapeutic value of small molecule activators of SIRT1 in general health and longevity”.
Previous research has demonstrated that SIRT1 protein could be a potential target for treatments to try and prolong life and prevent diseases of ageing. However, much animal research to date has focused on demonstrating how activators of this protein can reverse the detrimental effects of a high fat diet.
Therefore, though the current study also included mice fed a high fat diet, the main aim of researchers was to see what the effects could be when mice were fed their normal diet.
They found generally promising results. Overall they found that mice fed a normal diet supplemented with SRT1720, a chemical which is thought to activate SIRT1, had a longer natural lifespan (about five weeks longer on average). During their lifetime, additional tests also suggested they had improved muscle function and coordination, improved metabolism, improved glucose tolerance, decreased body fat and cholesterol.
All in all this suggests that giving the mice this supplement could protect them from the equivalent of metabolic syndrome in humans, and reduce the risk of diseases such as heart disease and diabetes. This is potentially important, as these types of disease are now a leading cause of disability and death in the developing world.
This research is at a very early stage, and we don’t know whether a treatment could be developed for testing in humans, and if it was, whether it would be safe or effective.
Though seeing the potential billions of pounds that could be made from a safe and effective anti-ageing drug, we would be extremely surprised if this study did not lead to further research into SRT1720 and SIRT1.
Analysis by Bazian. Edited by NHS Choices.
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