Last updated January 23, 2018 at 1:25 pm
There’s no getting around it – we need anaesthetics to perform surgery. And while they are generally a safe risk in expert hands, we don’t really understand how they work.
The latest research from the Queensland Brain Institute at the University of Queensland sheds new light on how general anaesthetics affect the brain – and it turns out there’s a lot more to it than just putting you to sleep.
“We looked at the effects of propofol – one of the most common general anaesthetic drugs used during surgery – on synaptic release”, said QBI researcher Associate Professor Bruno van Swinderen. “We know from previous research that general anaesthetics including propofol act on sleep systems in the brain, much like a sleeping pill. 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 team used an advanced imaging technique called single-particle tracking photoactivated localisation microscopy, which uses fluorescent dyes to track and image pairs of molecules. They were tracking the movements of a molecule called syntaxin1A by using rat and fly models in the lab.
Lead author and PhD student Adekunle Bademosi said they “found that propofol restricts the movement of a key protein (syntaxin1A) required at the synapses of all neurons. This restriction leads to decreased communication between neurons in the brain.”
So basically, they could tell that a protein the brain needs to make neurons talk to each other gets held back.
While this finding doesn’t tell the whole story, it’s an important piece of information according to Associate Professor van Swinderen.
“We think that widespread disruption to synaptic connectivity – the brain’s communication pathways – is what makes surgery possible, although effective anaesthetics such as propofol do put you to sleep first.”
The authors also suggest that this mechanism contributes to why people are groggy and disorientated after surgery, saying in the study “re-establishing functional connectivity after neurotransmission has returned to normal levels across the brain would likely involve a different process than falling asleep or waking up.”
Not only could this discovery make surgery safer for the general population, but it could have big impacts when it comes to brain health. Associate Professor van Swinderen says “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. “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.”
The authors suggest that future research studies the same mechanism in different anaesthetics.
This research was published in Cell Reports.