General Anesthesia May Work by Reducing Neuron Communication

Although general anesthesia is one of the most commonly performed medical procedures around the world, scientists have remained unsure of how it works. Now, based on the findings of a new study, Australian researchers have a greater understanding of the complex ways in which general anesthetics act on the brain.

Researchers from the University of Queensland (UQ) found that, far more than just inducing sleep, general anesthesia appears to reduce communication between neurons. The discovery may lead to improved drugs for surgery and have implications for people whose brain connectivity is vulnerable, such as young children or those with Alzheimer’s or Parkinson’s disease.

The research was conducted at Professor Frederic Meunier’s laboratory at Queensland Brain Institute (QBI), where super-resolution microscopy techniques allowed the researchers to understand how the anesthetics worked on single cells.

The researchers looked at the effects of propofol — one of the most common general anesthetic drugs used during surgery — on synaptic release. Synaptic release is 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,” said UQ researcher Associate Professor Bruno van Swinderen.

“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.”

Ph.D. student Adekunle Bademosi said the discovery sheds new light on how general anesthesia acts on the brain. “We 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,” he said.

According to van Swinderen, the finding contributes to understanding how general anesthesia works, and could explain why people experience grogginess and disorientation after coming out of surgery.

“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,” said van Swinderen.

“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.”

Van Swinderen says that more research is needed to determine if general anesthetics have any lasting effects in these vulnerable groups of people.

Dr. Victor Anggono, whose laboratory at QBI focuses on synaptic mechanisms, was a partner in the study.

Source: University of Queensland

Posted by Patricia Adams