Child anaesthetics cause brain damage in rats
Drugs commonly used to anaesthetise children have been shown to cause brain damage and learning problems in infant rats, a new study said today.
The researchers pointed out that anaesthetics are needed for operations and surgery is the only option for some children with life-threatening conditions.
But they said that if surgery really does not have to be performed early in life, it might be wise to postpone it.
For the study, published in the Journal of Neuroscience, researchers gave seven-day-old rats a combination of midazolam, nitrous oxide and isoflurane.
These drugs are commonly used to put children to sleep for operations.
As the rats recovered from the anaesthetic, the research team at the Washington University School of Medicine in St Louis, USA, divided them into three groups.
One group was killed the next day and the rats’ brains examined, the second grew to be a month old and the third reached adulthood.
The rats were given the drugs during a brain growth spurt period called synaptogenesis which lasts for the first few weeks of a rat’s life.
In humans the period extends from the later stages of pregnancy until about the age of three.
During this period, nerve cells in the brain make connections and form networks but if something interferes with that, they are designed to kill themselves.
In the study the researchers found moderately severe cell death had occurred in several regions of every rat brain studied.
When the rats were put in mazes designed to test learning and memory, those that had been anaesthetised performed worse than those that had not been given the drugs.
The team also found the rats appeared to behave normally in most other ways and there were no outward signs of brain damage.
Senior investigator John W Olney, a professor of neuropsychopharmacology, said: "That's important because if similar brain damage had occurred in a human infant it appears there would not be any overt signs that would alert you to it."
A child is born with an excess number of nerve cells and some cell death is normal in the developing brain.
But the study found that in rats, when drugs interfered with the cell while it was trying to make connections, the self destruction rate rose to abnormally high proportions.
Professor Olney said surgery is the only option for some children with life-threatening conditions and it can only be carried out with an anaesthetic.
"But some paediatric surgery is elective,” he said. “In light of these findings I would recommend that if surgery really does not have to be performed early in life, it would be prudent to postpone it."
