Published: Saturday, May 18, 2020
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The Conversation by Adam D Hines
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Globally, over 350 million operations are performed each year. Most of us will need general anesthesia at least once in our lifetime.
Although anesthesia is considered one of the most safe medical practices, it’s still not clear how exactly the drugs act in the brain.
It has been a mystery for over 180 years since the introduction of general anesthesia in medicine.
Journal of Neuroscience published a study that provides new insights into the intricate process. The effects of general anesthetics seem to be limited to specific brain regions that are responsible for alertness and vigilance.
Brain cells in balance
A study on fruit flies revealed a possible way for anesthetics to interact with certain types of neuron (brain cells), which has to do with protein. The brain contains 86 billion neurons, and they are not all the same. It is these differences that make general anesthesia effective.
We’re not in the dark about how anesthetics affect us. A landmark 1994 discovery explains why anesthetics can cause us to lose consciousness so rapidly.
To better understand finer details, it is important to first look at the differences between our brain cells.
There are two major categories of brain neurons.
First, we have “excitatory neurons” that are responsible for our alertness and arousal. Second, we have “inhibitory neurons” – their job is to regulate the excitatory neurons.
In our daily lives, inhibitory and excitatory neurons constantly work together to balance each other.
Inhibitory neurons “silence” excitatory neurons that keep us awake when we fall asleep. This occurs gradually, which may explain why you feel more tired throughout the day.
This is because general anesthetics accelerate this process, by silencing excitatory neuronal activity without the inhibition of inhibitory neurons. Your anesthetist may tell you they will “put you to bed” during the procedure. It’s the same process.
Sleeping Specially
We know that anesthetics make us sleepy, but the question is: “Why do we remain asleep during surgery?” You would be shocked if you fell asleep in bed and someone tried to perform surgery on you.
There is still no consensus on why people remain unconscious after general anesthesia during surgery.
Researchers have offered several possible explanations over the past two decades, but all of them seem to point towards one common cause. When exposed to anesthetics, neurons stop communicating with each other.
Although the concept of “cells communicating with each other” might sound strange, it is a basic one in neuroscience. Our brains would not be able function without this communication. It also allows the brain know what is happening in the rest of the body.
What have we discovered?
According to our new study, general anesthetics seem to block excitatory neuronal communication but not inhibitory neurons. Although this concept is not new, we have found compelling evidence to explain why only excitatory neuronal activity is affected.
Proteins are required for neurons to communicate. These proteins are responsible for getting neurons to release neurotransmitters. These messenger molecules are responsible for sending signals from one neuron into another. Dopamine, serotonin, and adrenaline are all examples of neurotransmitters.
We found that anesthetics affect the ability of these protein to release neurotransmitters but only on excitatory neurons. We used Drosophila fruit flies with super resolution microscopy and Drosophila melanogaster to test this.
Excitatory and inhibitive neurons differ from one another in part because they express different forms of the same proteins. It’s like two identical cars, one with a green sports package and the other just red and standard. Both do the same things, but one is a bit different.
The release of neurotransmitters is a complex procedure that involves many different proteins. General anesthetics will not work if one part of the puzzle doesn’t fit together perfectly.
In order to better understand why anesthetics are only effective in stopping excitatory communication, the next step is to identify which part of the puzzle differs.
Our results suggest that general anesthetics can cause massive global inhibitions in the brain. These drugs are able to put us to bed and keep us there by silencing our excitability on two levels.
This article was republished by The Conversation under the Creative Commons License. The original article can be read.
Source: Medical Xpress