There are many anti-aging paths, I don't know which one is better to use! Recently, John Speakman, an academician of the British Academy of Medical Sciences and a member of the Royal Society, currently serving in the Institute of Genetics and Developmental Biology of the Chinese Academy of Sciences in the mainland, jointly studied with a team of mainland scientists and found that if you want to live a long life, body temperature is more important than metabolic rate, and the article was published in the top journal Nature on March 14 [1].
Low body temperature is more important than low metabolism
Previously, the time school was in "Hibernation and Longevity, Low Metabolism and Anti-Aging!" It is mentioned in the "Secret of Marmot Longevity" that by reducing metabolism, marmots can make aging pause during hibernation, but low body temperature and low metabolism often go in and out together, and it is difficult to determine which factor prolongs life. Just like in 2006, scientists through gene editing, reduced the body temperature of mice, found that the lifespan of mice is extended, which can also be explained as: lower body temperature leads to decreased metabolism, and low metabolism prolongs lifespan [2]. For example, under caloric restriction, animals with longer lifespans have lower metabolic rates, but also lower body temperatures [3-4].
Therefore, scientists hope to separate body temperature and metabolism, so that they can break their heads to see who can affect life expectancy more
The researchers designed a special scenario using the thermal neutral zone.
People who wear clothes, the heat neutral zone is 14.8-24.5 ° C, at this time we will feel that the ambient temperature is very comfortable, neither cold to shivering, nor hot to sweat, panting, body temperature and metabolism are very stable [5-6]. Once the ambient temperature is higher than in the heat-neutral zone, our body temperature rises, and then we maintain a stable body temperature by sweating, and the metabolic rate also rises with body temperature.
Small mammals, on the other hand, are able to autonomously lower their body metabolic rate and reduce thermogenesis to avoid hyperthermia [1]. Their body temperature and metabolism change in the opposite direction!
Therefore, the researchers selected laboratory mice with a thermal neutral zone of 26-32 °C and a striped hamster with a thermal neutral zone of 32.5 °C [7-9]. The two small mammals were placed at 32.5 °C, and their body temperature increased, but their metabolic rate changed in the opposite direction, followed by a shortened lifespan.
Note: With the change of temperature, it can be seen that the survival rate of experimental animals at 32.5 °C decreases significantly, and the mortality rate increases significantly
The researchers then tried to fix their metabolic rate and continue to test whether they could reverse the change by lowering their body temperature.
The ambient temperature is still set at 32.5 ° C, and the daily energy consumption measured by the researchers confirms that the experimental animals may still reduce their metabolism autonomously due to the perception that the ambient temperature is higher than the thermal neutral zone, and at the same time, the researchers use small electric fans to force convection on them, increasing the heat loss and reducing their body temperature to room temperature (21 ° C).
The results showed that the mortality rate and average lifespan of the experimental animals at this time were not significantly different from those at room temperature, and the shortening of life expectancy was indeed reversed [1].
Figure Note: At an ambient temperature of 32.5 °C, the daily energy consumption of experimental animals is basically the same regardless of forced convection, which is lower than that of 21 °C
Comparing the two groups of experimental animals under room temperature and high temperature environment + forced convection conditions, it will be found that the decrease in metabolic rate does not significantly prolong life under the same body temperature, while comparing the high temperature environment and high temperature environment + forced convection conditions, it is found that the metabolism is the same, and the life change brought about by body temperature level is very obvious [1].
The researchers concluded that body temperature affects lifespan more than metabolism [1].
Why does hypothermia prolong life?
Since body temperature has a greater impact on lifespan, what mechanism does it use to prolong life? There are already several possible explanations.
First, hypothermia activates DAF-16/FOXO longevity signals. The researchers found that low temperatures activate the IL-1 sensory neurons of Caenorhabditis elegans, which stimulate intestinal receptors through signal transmission and activate the longevity gene FOXO transcription factor DAF-16, thereby prolonging the lifespan of nematodes through the brain-intestine axis (logical relationship: low-temperature sensory neurons intestinal FOXO transcription factor activation) [10]. Since the FOXO signaling pathway is highly similar in all animals, it is not excluded that this life extension pathway is also present in humans.
Figure Note: Low temperature activation of DAF/FOXO signal, Caenorhabditis elegans life extension, high temperature inhibits DAF/FOXO signal, shorten the life of nematodes
Secondly, hypothermia can also activate the adiponectin receptor PAQR-2. Also in nematodes, researchers have found that PAQR-2 signaling, a conglomerate of the adiponector receptor AdipoR2, can detect temperature drops and enhance the biosynthesis of two omega-6 polyunsaturated fatty acids, γ-linolenic acid, and arachidonic acid, thereby initiating autophagy in the epidermis, delaying the decline in collagen content with age, and prolonging lifespan [11].
Note: Low temperature activates PAQR-2 signaling, enhances omega-6 polyunsaturated fatty acid synthesis, initiates autophagy, and prolongs life
It has been found that both rats and human subjects in low-temperature environments have experienced elevated serum adiponectin levels, which can induce autophagy in a variety of tissues, such as the heart, liver, and skeletal muscle (in fact, in mice that have been at 4°C for 1 hour, increased autophagic activity of multiple tissues has been observed) [12-17].
This means that anti-aging pathways such as "low temperature activation of adiponectin-induced autophagy" may also exist in humans.
Interestingly, by the way, adiponectin levels in blood and skeletal muscle also increase during exercise, and perhaps the principle of exercise anti-aging can be explained by adiponectin-induced autophagy [18].
The scientists found that the GH receptor increases or decreases with water temperature in rainbow trout
In addition, the GH/IGF-1 axis is also an explanation. The GH/IGF-1 axis (growth hormone/insulin-like growth factor-1 axis) is an essential pathway during growth and development, and as we age it becomes a pro-aging factor in the body, so inhibiting this pathway later in life can prolong the lifespan of the organism. Scientists have found that fish, as thermothermal animals, have a significant decrease in growth hormone receptors in cold water and increase when the water temperature rises, suggesting that hypothermia has an inhibitory effect on this pathway [19].
Finally, hypothermia may also have some anti-aging effect. When the temperature changes, so does the rate of chemical reactions in the organism [20]. As a result, hypothermia reduces the rate of life activities such as protein production and DNA transcription, and relatively, the frequency of mutation errors in the process is also less, reducing the accumulation of errors and reducing the pressure on the repair system in the body, thereby delaying aging [21].
Note: Metabolic rate hypothesis
So how to lower the body temperature?
Laboratory animals can change body temperature through gene editing, humans can not, here are two ways to safely lower body temperature:
No.1
Calorie restriction:
Calorie restriction can be described as a lark, and it has its way down to metabolism and body temperature. Calorie intake is about 30%-50% less than in healthy, normal individuals, and the body temperature of many mammals decreases. For example, rhesus monkeys whose caloric intake was reduced by 30% had a decrease in core body temperature by about 0.5°C [22].
This is because the energy intake is greatly reduced, and the body has to abandon the car in order to save energy. At the same time, triiodothyronine (a thyroid-released hormone used to regulate body temperature) is also lowered in the blood, causing body temperature to drop [23].
No.2
Athletic Training:
In the 1870s, scientists found that people who had been running for a long time had a lower body temperature than those who did not exercise, and they were more adaptable when the temperature of the external environment changed, so it can be seen that perseverance is likely to be conducive to lowering body temperature and keeping body temperature stable .24]
Finally, this article also reminds us: in the high temperature environment, turn on the air conditioner in time to reduce the ambient temperature, blow the electric fan to increase the heat loss, this is out of the consideration of cherishing life, do not force yourself ~
Time Pie reviews
The researchers took into account changes in the amount of food consumed by laboratory animals, body weight, and pathogen load (temperature accelerates the multiplication of bacteria in animals)[1], but did have some drawbacks:
For example, mice and hamsters may suffer from heat stroke or other diseases in a 32.5 °C environment, and the experiment did not record the cause of death of the subjects, which means that the subjects may not die, and the mechanism by which high body temperature exerts its negative effects is not clear. There are also experiments in which changes in body temperature with the age of experimental animals are not taken into account [1].
The biggest highlight of this experiment is that the researchers skillfully used special situations to change body temperature and metabolism in the opposite direction, and separated the effects of the two on lifespan.
We can expect better research to answer this question.
—— TIMEPIE ——
Here is a time school that only does the most hard-core continuation research, focusing on "longevity technology" science. Day and night to read the literature to write only to bring you the latest, most comprehensive cutting-edge anti-aging information, welcome to leave your views and doubts in the comment area; day more motivation comes from your attention and sharing, anti-aging road with you side by side!