2024-01-14 20:04:09
This has to do with the sex hormone testosterone, according to a new study University of Pennsylvania. The researchers hope that this knowledge will lead to new guidelines for the type and amount of anesthetics.
Gender differences in biology are regularly overlooked in scientific research. These usually disadvantage women, who may have different reactions to medications, diseases or treatments compared to men. This also applies to anesthesia, an artificial state of unconsciousness caused by medication. Women stay awake longer and recover faster after anesthesia than men. They also wake up unintentionally more often.
Researchers from Pennsylvania University therefore decided to investigate where this difference in sensitivity to anesthesia comes from. They examined both mice and humans, using behavioral and neurocognitive tests. It showed that the difference is probably caused by the sex hormone testosterone, which is more common in men than in women.
What is anesthesia?
During anesthesia, or ‘general anesthesia’, a patient is administered substances that numb the body and suppress consciousness. Although the procedure is regularly referred to by both patients and doctors as a form of sleep, it is more akin to a coma, according to previous research. Brain activity decreases sharply under anesthesia. This makes the activity comparable to that of someone whose brain stem no longer functions. “It’s a reversible coma, but it’s a coma nonetheless,” researcher Emery Brown previously told Scientias.nl.
Sticker on the nose
The researchers first decided to measure how quickly someone wakes up from anesthesia. To do this, they stuck a sticker on the snout of mice that the animals could remove with their paws. When they did this, it was the sign that the mice had emerged from anesthesia. The test was slightly different in humans. They heard sound signals while their response was monitored as a test of consciousness and cognition. In addition, their brain activity was monitored using an electroencephalogram (EEG), a device that records electrical signals in the brain. A technique also used in clinical situations is used to determine the depth of anesthesia.
Hypothalamus
To the researchers’ surprise, the EEG showed no differences between men and women, in neither mice nor humans. Therefore, the researchers did a more detailed analysis of the whole brain activity of mice under anesthesia. It showed that male mice had more activity in the hypothalamus, a brain region involved in regulating sleep and wakefulness. Testosterone and estrogen were already known to influence this area, so the study suggests that testosterone plays an important role in stimulating natural sleep. And indeed, mice that had been castrated became less sensitive to anesthesia, while mice that were given testosterone became more sensitive.
Anesthesia of the future
Before the knowledge can be applied, more research is needed to determine how sex hormones influence other aspects of sleep and wakefulness, such as dream time, REM sleep and circadian rhythms. The researchers suspect that their results could have important consequences for the use of anesthesia. Consider other criteria when choosing a suitable anesthetic agent and dosage, dosages and the safety risks of anesthetics.
When you are under anesthesia, you do not completely lose consciousness
That is one of the conclusions that Finnish researchers previously drew based on an extensive study in the journal Anesthesiology. The research strongly suggests that general anesthesia is more similar to sleep than previously thought. In the experiment in which healthy subjects were put under light anesthesia, it turned out that almost all of them had dreamed while under anesthesia. And those dreams sometimes turned out to be mixed with reality. It – together with the other findings – strongly suggests that people are not completely unconscious when they are under anesthesia. “The state of consciousness during anesthesia may be comparable to the situation during natural sleep,” says researcher Antti Revonsuo. “While people sleep they dream and the brain unconsciously observes the events and stimuli in the environment.”
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