General anesthesia may be more complex in its workings than we know now

By Dr. Ananya Mandal, MDJan 10 2018

Associate Professor Bruno van Swinderen from Queensland Brain Institute, University of Queensland with his colleagues have studied the workings of general anesthetics on the brain and found that these agents did more than just put a person to sleep. These findings could pave the way for better and more effective anesthetics they believe. The study was published in the latest issue of the journal Cell Reports.

According to van Swinderen, the team assessed the brain functioning after a person was anesthetized with a common general anesthetic agent called propofol. They looked at the synapses or the tiny connections that exist between the nerve cells or neurons. Small amounts of chemicals are released at these synapses to allow communication between the nerve cells.

Propofol, like most other general anesthetics induces sleep as is known from previous research, he said. New findings show that propofol is also capable of disrupting the workings of the synapses before the joints or connections (presynaptic) and this can affect the communication between the nerves of the whole brain. This disruption and change is different from being merely asleep says Associate Professor van Swinderen.

The team including PhD student Adekunle Bademosi also noted that propofol tends to stop the movement of a key protein (syntaxin1A) that is necessary for the synapses of all neurons. For this study the team looked at the effect of propofol on flies that were anaesthetised at the same concentration as humans. The syntaxin1A protein was found to be decreased in their brains. This means that the communication between the neurons decrease explains Bademosi. Associate Professor van Swinderen added that this could explain the drowsiness that follows an episode of anesthesia after waking up from it. There is also a significant disorientation he said that could be attributed to these molecular findings. He said that there is a sleep component associated with these drugs but there is also a disruption in the synaptic connectivity.

The work was carried out at Professor Frederic Meunier's laboratory at QBI using the super-resolution microscopy available there for checking on the synapses and their workings. Dr Victor Anggono partnered in the study as well.

This new finding could shed light on several degenerative brain diseases such as Alzheimer’s disease or Parkinson’s disease, he said. It could also provide an understanding to the working of these connections and their development in a growing infant and child. In the elderly with degenerative brain diseases and dementia too understanding the effects on the synaptic communications could be helpful in development of treatment strategies. General anesthesia could have a lasting effect on the very young and in the elderly. This has never been fully understood till now, said Associate Professor van Swinderen.

More studies are necessary to understand the lasting effects if any of these agents on the brain especially among children and infants and in the elderly. He said that it has been almost 180 years that general anesthesia is being practiced as we know it now and the workings of these drugs are still unclear.

Reference: http://www.cell.com/cell-reports/fulltext/S2211-1247(17)31878-8