During a stroke or cardiac arrest, oxygenation is interrupted, which can cause incurable damage to brain tissue. An enzyme could block this process.
- Hypoxia is a drop in the concentration of oxygen in the blood.
- The SQOR enzyme appears to have a protective effect on the brain, enabling it to resist hypoxia.
- Scientists hope to be able to create a treatment, useful for people who have suffered a stroke or cardiac arrest.
Oxygen is vital for our body and brain. When a person suffers a cardiac arrest or a stroke, the oxygenation of his brain is interrupted. This phenomenon, called hypoxia, can be fatal. In NatureCommunications, scientists have found a way to counter it. Initially, this team at Massachusetts General Hospital was working on a technique to generate a temporary state of death. “It is about putting human vital functions on pause, with the possibility of waking them up afterwards“, they explain. This state is comparable to that of hibernating animals. Fumito Ichinose, the director of this study, supposes that artificially reproducing this state could allow patients with incurable diseases “to wait“the arrival of a treatment.
Hypoxia resistant mice
The team relied on previous work carried out in 2005: they had shown that hydrogen sulphide can generate a temporary state of death in mice. However, this gas is also produced by the human brain in the event of hypoxia, when it accumulates in the tissues, this blocks the metabolism of neurons and can kill them. Fumito Ichinose and his team observed the effect of this gas on mice. At first, their body temperature dropped, then they remained still. “But, to our surprise, the mice quickly became tolerant to the effects of inhaling hydrogen sulfide, says the scientist. On the fifth day, they behaved normally and were no longer affected by the hydrogen sulphide.“They were no longer responding to severe hypoxia either.
What protects mice?
According to the researchers, the mice are protected by an enzyme present in their brain, capable of metabolizing hydrogen sulphide. When mice inhale this gas for more days in a row, the level of an enzyme increases, the sulfide: quinone oxidoreductase (SQOR). According to the researchers, this enzyme has a role in resistance to hypoxia. They confirmed this hypothesis by other observations: female mice are more resistant to hypoxia than males, yet they have higher levels of SQOR. “When SQOR levels are artificially lowered in females, they become more vulnerable to hypoxia“, they conclude. Conversely, the scientists artificially increased SQOR levels in the brains of male mice.”They have developed a strong resistance to hypoxiaThis artificial modification of the levels of the enzyme is a complex approach, but a drug, called SS-20, makes it possible to obtain similar effects. The researchers are currently working on an application in humans.We hope that one day we will have drugs that will work like SQOR in the body“, concludes the director of this study.
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