General anaesthetic more than just a super sleeping pill

Every day around the world tens of thousands of people needing surgery are given general anaesthetics – yet no one fully understands how they work.

Now the picture has become a little clearer thanks to Australian research published in the journal Cell Reports.

A team of scientists led by University of Queensland researcher Bruno von Swinderen has uncovered a key effect of the propofol – one of the most commonly used anaesthetic drugs – and confirmed that it does far more than simply put patients to sleep.

Von Swinderen’s team found that propofol profoundly disrupted a process known as synaptic release, the mechanism by which neurons communicate with each other.

“We know from previous research that general anaesthetics including propofol act on sleep systems in the brain, much like a sleeping pill,” he says.  

“But our study found that propofol also disrupts presynaptic mechanisms, probably affecting communication between neurons across the entire brain in a systematic way that differs from just being asleep. In this way it is very different than a sleeping pill.”

The disruption arises because the anaesthetic restricts the movement of a protein, known as syntaxin1A, that is essential for the operation of synapses.

The finding, adds von Swinderen, could explain why emerging from general anaesthesia is commonly accompanied by feelings of grogginess and disorientation.

It could also be a clue to why some people are more likely to experience adverse outcomes as a result of going under.

“The discovery has implications for people whose brain connectivity is vulnerable, for example in children whose brains are still developing or for people with Alzheimer’s or Parkinson’s disease,” explains von Swinderen.

“It has never been understood why general anaesthesia is sometimes problematic for the very young and the old. This newly discovered mechanism may be a reason.”