An attentive, nurturing mother may be able to help her children better resist the temptations of drug use later in life, according to a study involving the University of Adelaide.
A paper published in the Journal of Neuroscience today by researchers from Duke University in the United States and the University of Adelaide shows for the first time how mothering can strengthen an offspring's immune system in the brain.
Using rats as a model, neuroscientists have demonstrated that if babies are nurtured adequately it increases the production of a molecule in the brain's immune system called Interleukin-10, leaving them less susceptible to drug cravings as an adult.
Dr Mark Hutchinson from the University of Adelaide's School of Medical Sciences and lead researcher Assistant Professor Staci Bilbo from Duke University exposed baby rats to morphine and noted their follow-up cravings for the drug.
"Rat pups who were well nurtured by their mothers showed less cravings for morphine after the initial dose than those rats who were left alone," Dr Hutchinson said.
"Morphine activates the glial cells of the brain to produce inflammatory molecules which signal a reward centre of the brain, contributing to addiction. But IL-10 works against that inflammation and reward. It completely knocks out this drug-seeking behaviour.
"The more IL-10 produced in the brain, the less likely morphine causes an increase in craving or relapse weeks after initially being exposed to the drug," Dr Hutchinson said.
The rats who experienced "high-touch" mothering produced four times as much IL-10 as the control animals.
"It's important to note that the genetic modification created by the mothering didn't change the initial rewarding effect of the morphine. It altered the craving for that reward much later on," said Assistant Professor Bilbo.
This is the first study to show how morphine causes a molecular response specifically in the glial cells of the brain's reward centres, which have only recently been identified as part of drug addiction's circuitry.
"Excitingly, we have also shown that a drug that targets these brain immune cells is also able to protect against drug cravings, providing a new way to treat drug addiction," Dr Hutchinson said.
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