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

Posted by BeauHD on from the behind-the-scenes dept.

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.

20 of 92 comments (clear)

  1. Stitch in time by Camel+Pilot · · Score: 5, Interesting

    I friend of mine just had a colonoscopy and was laying on his side looking at a pattern on the wall just before being given propofol. He woke up looking at the same pattern and the Doc said everything was normal. He accused the Doc of haven't done anything and was conducting some fraud because he hadn't any sense any lapse in time. Propofol is like that.

  2. Propofol is great stuff by dlleigh · · Score: 4, Informative

    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.

    1. Re:Propofol is great stuff by demonlapin · · Score: 5, Informative

      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.

    2. Re:Propofol is great stuff by rfengr · · Score: 2

      Well the strange thing is I had no memory of being wheeled into the OR, until 2 weeks later, then BAM, a sudden flash of full memory. The stuff messes with your memory.

    3. Re:Propofol is great stuff by twdorris · · Score: 3, Interesting

      Posts like this are why I still come to Slashdot. This place is still the best resource I've found where people with such a diverse set of highly skilled talents can all post about experiences and information that they are intimately familiar with in their respective trades and we all learn / grow from that. Thanks!

    4. Re:Propofol is great stuff by gay358 · · Score: 2

      BTW, there is some evidence that propofol reduces sleep debt, unlike normal anesthesia:

      https://www.uchicagomedicine.o...

      "We concluded that the need to sleep was not accumulating inside rats that received propofol and therefore either propofol was preventing their "sleep debt" from building up or propofol was, like sleep, helping rats to discharge it."

      "So we then allowed rats to sleep naturally or gave them a period of sedation with propofol and looked to see how they recover. What we found is that recovery in rats given propofol occurred as quickly as recovery in rats allowed to sleep normally. We concluded that, at least in rats, subjects can discharge their sleep debt under propofol sedation to the same degree as they are able to do it using naturally occurring sleep."

  3. Are people vegetables? by sgage · · Score: 3, Informative

    "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 ;-)

    1. Re:Are people vegetables? by Baron_Yam · · Score: 3, Insightful

      >people are animals - capiche?

      And this is not pedantry at all. For most of human history, we've considered ourselves divinely special and separate from nature, and that attitude causes all sorts of problems.

      WE ARE JUST ANIMALS. Animals with the most intelligent brains on the planet, but animals nonetheless.

      I'm pretty sure most medical researchers understand that and simply use the term as a convenience, but they really ought not to.

    2. Re:Are people vegetables? by JoshuaZ · · Score: 3, Informative

      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.

  4. Re:feel everything but forget afterwards by Camel+Pilot · · Score: 3, Insightful

    If this were true there would be unmistakable markers of experiencing pain... such as elevated heart rate, blood pressure, pupil reflexes, etc.

  5. Re:feel everything but forget afterwards by edjs · · Score: 2

    A small minority remember everything and kept trying to "wake up" and "scream for them to stop".

    You may be thinking of cases where people are paralyzed but still conscious - for surgery you may be given separate drugs render you unconscious and immobilize you, and if they get the mix wrong you get the above nightmare.

  6. Re:But don't dare suggest ... by DontBeAMoran · · Score: 2, Funny

    Doctor: Now, just count backwards from 100... that's it... 99... 98... 97...
    Nerd: Wow, that's too fucking long, doc. Let's try it my way: for (ctr=100; ctr>0; ctr--) echo ctr; [falls unconscious]

    --
    #DeleteFacebook
  7. Re:But don't dare suggest ... by Waffle+Iron · · Score: 3, Insightful

    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 don't dare suggest that there is anything we don't understand about climate science. In that case, the science is fully settled and there is no sense questioning our understanding.

    Since we don't fully understand how they work, the only rational course of action is to deny that anesthetics exist.

  8. Re:feel everything but forget afterwards by demonlapin · · Score: 2

    It does happen, but it's exceedingly rare. Paralytics don't block autonomic responses - people who are in pain will still exhibit increased heart rate and blood pressure.

  9. Re:feel everything but forget afterwards by Beeftopia · · Score: 2

    They give anaesthesia to paraplegics even though they can't feel anything below the severed nerve location. That's because paraplegics will go into shock from the pain, even though they can't actually feel the pain. Like if a paraplegic gets a broken leg. So the pain is an actual phenomenon that anaesthesia somehow blocks.
     

  10. Re:But don't dare suggest ... by Waffle+Iron · · Score: 4, Insightful

    I am just curious about how much human activity really has to do with climate change..

    No, you're not.

  11. Re:Delicate dosing by demonlapin · · Score: 5, Informative

    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.

  12. Cool language by peppepz · · Score: 3

    Can we do without super childish language at least here on Slashdot? Super pretty please.

  13. Oh what you don't know... by eWarz · · Score: 4, Interesting

    I almost died in April 2017 of septic shock. During that time, medical staff assumed I was unconscious and unable to recollect a single thing. I had 4 surgeries and I was on a ventilator for many days and I was on enough drugs to kill an elephant. I remembered everything. Including some VERY personal conversations from certain staff members. It was all so vivid. I can't discuss most of it thanks to an ongoing malpractice suit against the hospital that caused the issue to begin with...however. Never assume your loved one doesn't hear you. They do. They hear you. They also hear the medical staff talking about their so called 'day' as they turn you, change various 'things', etc.'

  14. Re:Milk of Amnesia by SuiteSisterMary · · Score: 2

    I always try to remember, when coming out of anesthetic, to say something like 'what year is it? WHAT YEAR?!'

    Every time I mention that, I'm reminded about how lucky we are to live in a day and age when we can treat invasive surgery so casually, and when it's perfectly possible for somebody to have gone through five or six of these things for relatively minor ailments.

    Also, even more lucky, that I live in a country where I don't go bankrupt just for want to, say, not suffer from painful gall stones for the rest of my life.

    --
    Vintage computer games and RPG books available. Email me if you're interested.