Scientists Change Our Understanding of How Anaesthesia Messes With the Brain (sciencealert.com)

schwit1 shares a report from ScienceAlert: It's crazy to think that we still don't quite understand the mechanism behind one of the most common medical interventions -- general anaesthetic. But researchers in Australia just got a step closer by discovering that one of the most commonly used anesthetic drugs doesn't just put us to sleep; it also disrupts communication between brain cells. The team investigated the drug propofol, a super-popular option for surgeries worldwide. A potent sedative, the drug is thought to put us to sleep through its effect on the GABA neurotransmitter system, the main regulator of our sleep-and-wake cycles in the brain. But anyone who's been "put under" will know that waking up from a general anesthetic feels rather different from your usual morning grogginess. On top of that, some people can experience serious side-effects, so scientists have been trying to figure out what else the drugs might be doing in the brain.

Using live neuron cell samples from rats and fruit flies, the researchers were able to track neurotransmitter activity thanks to a super-resolution microscope, and discovered that propofol messes with a key protein that nerve cells use to communicate with each other. This protein, called syntaxin1A, isn't just found in animal models - people have it, too. And it looks like the anesthetic drug puts the brakes on this protein, making otherwise normal brain cell connections sluggish, at least for a while. The researchers think this disruption could be key to how propofol allows for pain-free surgery to take place - first it knocks us out as a normal sleeping pill would, and then takes things up a notch by disrupting brain connectivity. The research has been published in Cell Reports.

Comments

Propofol is great stuff

[dlleigh]

I had minor surgery a few years ago and they used propofol as part of the anesthesia.

I woke up feeling amazingly refreshed and relaxed. I can kinda see why Michael Jackson was using propofol every night... until it killed him.

Physicians like to too because of its memory blocking effect. There's less chance of malpractice suits if your patient can't remember anything, even from right before and right after the surgery when they aren't actually unconscious.

Re:Propofol is great stuff

[demonlapin]

Propofol also has a very short duration of action. The "fog of general anesthesia" is much more likely to be caused by the benzodiazepine sedatives that most will get prior to actual induction of anesthesia. Those benzos - classically, Valium (diazepam); today, usually Versed (midazolam) - are in the same class as Rohypnol (flunitrazepam, but famous as "roofies"). They're very good for treating acute anxiety, but they're also addictive, and seriously interfere with memory formation.

I'm an anesthesiologist, and unless someone is really climbing the walls with anxiety (not, actually, all that common), I don't give benzos. I give a solid dose of long-acting opioids right up front, and that's it. The only time I've ever had Versed, I got an eight-hour gap in my memory. Don't remember a thing. Rather obvious why it became popular as a "date-rape drug".

We do use propofol for colonoscopies, and it's a great drug for that, but most general anesthetics are conducted with gas anesthetics - they are cheaper and they are very easily monitored (we can easily see how much you're breathing in and out, and thus infer how likely you are to have any awareness). In most cases, propofol is used only to induce anesthesia - to make you unconscious so that you can be intubated. As soon as the breathing tube is in, the gas is turned on, and that's what you're waking up from. The advantage there is that, as with alcohol, people tend to get disinhibited before they lose consciousness. You don't want someone without a secured airway flailing around on the OR table (they might fall off). A slug of propofol takes them from conscious to comatose in a matter of seconds. By the time it wears off, the gas has kicked in.

Are people vegetables?

[sgage]

"This protein, called syntaxin1A, isn't just found in animal models - people have it, too."

You f-ing idiot, people are animals - capiche? Not demigods, not brains in vat (as much as some geeks would love that). Animals. Meat. We are great apes. Like gorillas and chimps and orangs and so forth. That's what makes life interesting ;-)

Re:Are people vegetables?

[JoshuaZ]

They were more careful than you give them credit for here. The quote explicitly says "animal models" so they weren't talking about all animals, just those used as model organisms.

Re:Delicate dosing

[demonlapin]

We generally don't care if you stop breathing - it's sort of our thing to breathe for you. Consciousness requires a great deal more coordination than the simple breathing centers, though. The same reason explains why anesthetics make you lose vision as a sense before you lose hearing - it's a more processing-intensive sense.

As for cardiac rhythms, gas anesthetics are arrhythmogenic, but it's usually not a problem. Spinals - as are given for most cesarean sections - are more likely to produce slow heart rates, as they disable the autonomic nerves as well as the sensory ones. However, we have drugs for that.