The anesthetic general, a mixture of a hypnotic sedative that makes us sleep, an opioid not feel pain and a muscle relaxant to suppress muscle tone -for adults- painkiller, have a more pervasive effect on the brain that induction of sleep, suggests a new study carried out by scientists from the University of Queensland (Australia), discovery that could lead to better drugs for use in surgery.
The team explains in Cell Reports that their “findings can provide a more complete understanding of general anesthesia.”
Using a technique known as single-molecule imaging microscopy, scientists were able toexplore the effect of propofol, a common general anesthetic, on individual cells. Specifically, they studied the effect of the drug on synaptic release, a mechanism through which nerve cells or neurons communicate with each other.
“We know from previous research that general anesthetics, including propofol, act on sleep systems in the brain, just like a sleeping pill,” says Bruno van Swinderen, work leader.
However, in his experiment they examined the effects of the drug on rats and flies, discovering that propofol could also act in a very different way. The drug “alters presynaptic mechanisms, which probably affects communication between neurons throughout the brain in a systematic way that differs from simply being asleep,” says van Swinderen.
Thus, propofol restricts the mobility of a protein called syntaxin 1A, necessary in neuronal synapses for neurons to communicate with each other.
Most signals are transported by chemical messengers called neurotransmitters. These are released by the presynaptic neuron and received in the postsynaptic cell.
The new finding is significant because, as the authors point out, “each neuron communicates with other neurons through neurotransmission mediated by syntaxin1A”, and the mechanism is the same in all species, from worms to humans.
Implications for people with Alzheimer’s
Although propofol and other general anesthetics numb us, it is their generalized interruption of synaptic connectivity or communication channels throughout the brain that makes surgery possible.
“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 disease or Parkinson’s,” adds van Swinderen.
Logically, more research is needed to determine whether or not general anesthetics produce long-term side effects in these vulnerable groups, and, as van Swinderen explains, “it has never been understood why general anesthesia is sometimes problematic for patients. younger and older, this recently discovered mechanism may be a reason.”