Hundreds of animal species can hibernate. The metabolic rate in their organisms is reduced tenfold. They can not eat and hardly breathe. This condition continues to be one of the biggest scientific mysteries. Solving it could lead to breakthroughs in many areas, from oncology to space flight. Scientists want to make a person hibernate.
“I worked in Sweden for a year and couldn’t get the gophers to fall asleep for a year,” admits Lyudmila Kramarova, senior researcher at the Institute of Theoretical and Experimental Biophysics of the Russian Academy of Sciences (Pushchino).
In the West, the rights of laboratory animals are detailed – the Declaration of Human Rights is resting. But experiments on the study of hibernation cannot be carried out.
– The question is, why should they sleep if it is warm in the gopher house and fed from the belly? Gophers aren’t stupid. Here in our laboratory, they would quickly fall asleep with me!
The kindest Lyudmila Ivanovna sternly taps her finger on the table and talks about the laboratory gopher who lived at her place. “Susya!” she called from the doorway. “Pay-pay!” – responded the gopher, which is generally not tamed. This Susya did not fall asleep even once in three years at home. In winter, when it got noticeably colder in the apartment, he climbed under the radiator and warmed his head. “Why?” asks Lyudmila Ivanovna. Maybe the regulatory center of hibernation is somewhere in the brain? Scientists don’t know yet. The nature of hibernation is one of the major intrigues in modern biology.
Thanks to Microsoft, our language has been enriched with another buzzword – hibernation. This is the name of the mode in which Windows Vista enters the computer in order to minimize power consumption. The machine seems to be turned off, but all the data is saved at the same time: I pressed the button – and everything worked as if nothing had happened. The same thing happens with living organisms. Thousands of different species – from primitive bacteria to advanced lemurs – are able to temporarily “die”, which is scientifically called hibernation, or hypobiosis.
The classic example is gophers. What do you know about gophers? Normal such rodents from the squirrel family. They dig their own minks, eat grass, breed. When winter comes, gophers go underground. This is where, from a scientific point of view, the most interesting thing happens. Gopher hibernation can last up to 8 months. On the surface, frost sometimes reaches -50, the hole freezes down to -5. Then the temperature of the limbs of the animals drops to -2, and the internal organs to -2,9 degrees. By the way, during wintering, the gopher sleeps in a row for only three weeks. Then it comes out of hibernation for a few hours, and then falls asleep again. Without going into biochemical details, let’s say that he wakes up to pee and stretch.
A frozen ground squirrel lives in slow motion: its heart rate drops from 200-300 to 1-4 beats per minute, episodic breathing – 5-10 breaths, and then their complete absence for an hour. The blood supply to the brain is reduced by about 90%. An ordinary person cannot survive anything close to this. He is not even able to become like a bear, whose temperature drops quite a bit during hibernation – from 37 to 34-31 degrees. These three to five degrees would have been enough for us: the body would have fought for the right to maintain the heart rate, breathing rhythm and restore normal body temperature for several more hours, but when the energy resources run out, death is inevitable.
Do you know what a gopher looks like when it sleeps? asks Zarif Amirkhanov, senior researcher at the Institute of Cell Biophysics. “Like potatoes from the cellar. Hard and cold. Only furry.
In the meantime, the gopher looks like a gopher – it cheerfully gnaws seeds. It is not easy to imagine that this cheerful creature could suddenly fall into a stupor for no reason and spend most of the year like this, and then, again, for no reason at all, “fall out” of this stupor.
One of the mysteries of hypobiosis is that the animal is quite capable of regulating its condition on its own. A change in ambient temperature is not at all necessary for this – lemurs from Madagascar fall into hibernation. Once a year, they find a hollow, plug the entrance and go to bed for seven months, lowering their body temperature to +10 degrees. And on the street at the same time all the same +30. Some ground squirrels, for example, Turkestan ones, can also hibernate in the heat. It’s not so much the temperature around, but the metabolism inside: the metabolic rate drops by 60-70%.
“You see, this is a completely different state of the body,” says Zarif. – Body temperature drops not as a cause, but as a consequence. Another regulatory mechanism is activated. The functions of dozens of proteins change, cells stop dividing, in general, the body is completely rebuilt in a few hours. And then in the same few hours it is rebuilt back. No outside influences.
Firewood and stove
The uniqueness of hibernation is that the animal can first cool down and then warm up without outside help. The question is how?
“It’s very simple,” says Lyudmila Kramarova. “Brown adipose tissue, have you heard?
All warm-blooded animals, including humans, have this mysterious brown fat. Moreover, in infants it is much more than in an adult. For a long time, its role in the body was generally incomprehensible. In fact, there is ordinary fat, why also brown?
– So, it turned out that brown fat plays the role of a stove, – explains Lyudmila, – and white fat is just firewood.
Brown fat is able to warm up the body from 0 to 15 degrees. And then other fabrics are included in the work. But just because we’ve found a stove doesn’t mean we’ve figured out how to make it work.
“There must be something that turns on this mechanism,” Zarif says. – The work of the whole organism is changing, which means that there is a certain center that controls and launches all this.
Aristotle bequeathed to study hibernation. It cannot be said that science has been doing just that since 2500 years. Seriously this problem began to be considered only 50 years ago. The main question is: what in the body triggers the hibernation mechanism? If we find it, we will understand how it works, and if we understand how it works, we will learn how to induce hibernation in non-sleepers. Ideally, we are with you. This is the logic of science. However, with hypobiosis, normal logic did not work.
It all started from the end. In 1952, the German researcher Kroll published the results of a sensational experiment. By introducing an extract of the brain of sleeping hamsters, hedgehogs and bats into the body of cats and dogs, he caused a state of hypobiosis in non-sleeping animals. When the problem began to be dealt with more closely, it turned out that the hypobiosis factor is contained not only in the brain, but in general in any organ of a hibernating animal. Rats obediently hibernated if they were injected with blood plasma, stomach extracts, and even just the urine of sleeping ground squirrels. From a glass of gopher urine, monkeys also fell asleep. The effect is consistently reproduced. However, it categorically refuses to be reproduced in all attempts to isolate a particular substance: urine or blood cause hypobiosis, but their components separately do not. Neither ground squirrels, nor lemurs, nor, in general, any of the hibernators in the body was found anything that would distinguish them from all the others.
The search for the hypobiosis factor has been going on for 50 years, but the result is almost zero. Neither the genes responsible for hibernation nor the substances that cause it have been found. It is not clear which organ is responsible for this condition. Various experiments included the adrenal glands, and the pituitary gland, and the hypothalamus, and the thyroid gland in the list of “suspects”, but each time it turned out that they were just participants in the process, but not its initiators.
“It is clear that far from the entire range of substances that are in this dirty fraction is effective,” says Lyudmila Kramarova. — Well, if only because we mostly have them too. Thousands of proteins and peptides responsible for our life with ground squirrels have been studied. But none of them – directly, at least – are connected with hibernation.
It has been precisely established that only the concentration of substances changes in the body of a sleeping gopher, but whether something new is formed there is still unknown. The further scientists advance, the more they are inclined to think that the problem is not the mysterious “sleep factor”.
“Most likely, this is a complex sequence of biochemical events,” says Kramarova. – Perhaps a cocktail is acting, that is, a mixture of a certain number of substances in a certain concentration. Maybe it’s a cascade. That is, the consistent effect of a number of substances. Moreover, most likely, these are long-known proteins that everyone has.
It turns out that hibernation is an equation with all known ones. The simpler it is, the more difficult it is to solve.
With the ability to hibernate, nature made a complete mess. Feeding babies with milk, laying eggs, maintaining a constant body temperature – these qualities are neatly hung on the branches of the evolutionary tree. And hypobiosis can be clearly manifested in one species and at the same time be completely absent in its closest relative. For example, marmots and ground squirrels from the squirrel family sleep in their minks for six months. And the squirrels themselves do not think to fall asleep even in the most severe winter. But some bats (bats), insectivores (hedgehogs), marsupials and primates (lemurs) fall into hibernation. But they are not even second cousins to gophers.
Some birds, reptiles, insects sleep. In general, it is not very clear on what basis nature chose them, and not others, as hibernators. And did she choose? Even those species that are not familiar with hibernation at all, under certain conditions, easily guess what it is. For example, the black-tailed prairie dog (a family of rodents) falls asleep in a laboratory setting if deprived of water and food and placed in a dark, cold room.
It seems that the logic of nature is based precisely on this: if a species needs to survive the season of starvation in order to survive, it has an option with hypobiosis in reserve.
“It seems that we are dealing with an ancient regulatory mechanism, which is inherent in any living creature in general,” Zarif thinks aloud. – And this leads us to a paradoxical thought: it is not strange that gophers sleep. The strange thing is that we ourselves do not hibernate. Perhaps we would be quite capable of hypobiosis if everything in evolution developed in a straight line, that is, according to the principle of adding new qualities while maintaining the old ones.
However, according to scientists, a person in relation to hibernation is not entirely hopeless. Aboriginal Australians, pearl divers, Indian yogis can minimize the physiological functions of the body. Let this skill be achieved by long training, but it is achieved! So far, no scientist has been able to put a person into a full-fledged hibernation. Narcosis, lethargic sleep, coma are states close to hypobiosis, but they have a different basis, and they are perceived as a pathology.
Experiments to introduce a person into hibernation will soon begin Ukrainian doctors. The method they developed is based on two factors: high levels of carbon dioxide in the air and low temperatures. Perhaps these experiments will not allow us to fully understand the nature of hibernation, but at least turn hypobiosis into a full-fledged clinical procedure.
Patient sent to sleep
At the time of hibernation, the gopher is not afraid not only of the cold, but also of the main gopher ailments: ischemia, infections, and oncological diseases. From the plague, a waking animal dies in a day, and if it is infected in a sleepy state, it does not care. There are huge opportunities for physicians. The same anesthesia is not the most pleasant state for the body. Why not replace it with a more natural hibernation?
Imagine the situation: the patient is on the verge of life and death, the clock counts. And often these hours are not enough to perform an operation or find a donor. And in hibernation, almost any disease develops like in slow motion, and we are no longer talking about hours, but about days, or even weeks. If you give free rein to your imagination, you can imagine how hopeless patients are immersed in a state of hypobiosis in the hope that someday the means necessary for their treatment will be found. Firms engaged in cryonics do something similar, only they freeze an already dead person, and it is hardly realistic to restore an organism that has lain for ten years in liquid nitrogen.
The mechanism of hibernation can help to understand a variety of ailments. For example, the Bulgarian scientist Veselin Denkov in his book “On the Edge of Life” suggests paying attention to the biochemistry of a sleeping bear: “If scientists manage to obtain in its pure form a substance (presumably a hormone) that enters the body from the hypothalamus of bears, with the help of which life processes are regulated during hibernation, then they will be able to successfully treat people suffering from kidney disease.
So far, doctors are very wary of the idea of using hibernation. Still, it is dangerous to deal with a phenomenon that is not fully understood.