Anesthesia Only Temporarily Disrupts Brain Cell Connections
In a new study, researchers tested the effects of general anesthesia on the brain health of mice models. Over the past few years, researchers have been concern over the potentially negative effects that general anesthesia has on children's long-term mental health. The study found that anesthesia only temporarily disrupts the connections between brain cells.
"Since these procedures are unavoidable in most cases, it's important to understand the mechanisms associated with the potentially toxic effects of anesthetics on the developing brain, and on the adult brain as well," said co-investigator, Shelley Halpain, a professor of biology at the University of California San Diego and the Sanford Consortium for Regenerative Medicine. "Because the clinical studies haven't been completed, preclinical studies, such as ours, are needed to define the effects of various anesthetics on brain structure and function."
For this study, researchers from the UC San Diego and Weill Cornell Medical College in New York focused on one of the most commonly used general anesthetic, isoflurane, which is a derivative of ether. The team took the neurons from the hippocampus of embryonic rats. They cultured the brain cells for three weeks so that the neurons had time to mature and develop a network of synaptic connections and dendritic spines. The researchers then exposed the cells to isoflurance and examined any structural changes.
"Imaging of human brain synapses at this level of detail is impossible with today's technology and it remains very challenging even in laboratory rodents," Halpain explained reported in the press release. "It was important that we performed our study using rodent neurons in a culture dish, so that we could really drill down into the subcellular and molecular details of how anesthetics work."
The researchers discovered that brief exposure to the anesthetic caused a change in the number and size of the dendritic spines. Within 10 minutes of exposure, there were noticeable decreases in the number of dendritic spines. The size of the spines also changed. Despite these changes, the researchers found that after the isoflurane was washed out of the cultures, the spine loss and shrinkage returned backed to normal.
"Our study was reassuring in the sense that the effects are not irreversible and this fits in with known clinical effects. For the most part, we find that the effects are reversible," senior author, Hugh Hemmings, Jr., chair of anesthesiology at Weill Cornell Medical College, said. "We clearly see an effect-a very marked effect on the dendritic spines-from use of this drug that was reversible, suggesting that it is not a toxic effect, but something more relevant to the pharmacological actions of the drug. Connecting what we found to the cognitive effects of isoflurane will require much more detailed analysis."
The study was published in the journal, PLOS ONE.