UNSW says gut compound reversed some rat harm
A UNSW Sydney study found sodium butyrate reversed some damage linked to prenatal opioid exposure in rats, raising hopes for a future treatment for babies exposed to opioids before birth.
The research, published in Translational Psychiatry on 16 September 2026, examined pups born to pregnant rats given methadone from mid-pregnancy through birth and early nursing.
Those pups showed behavioural and health problems similar to issues associated with babies exposed to opioids in the womb. However, pups treated with sodium butyrate alongside methadone showed marked improvements. In some tests, they performed as well as pups not exposed to methadone.
Associate Professor Kelly Clemens from UNSW Sydney’s School of Psychology said: “For the first time, we’ve shown it may be possible to reverse some of the lasting effects of opioid exposure before birth.”
Gut bacteria and brain development changed
The study is part of a broader project led by Clemens to improve life outcomes for babies born to mothers using opioids.
Clemens said opioids affect multiple internal systems in both a pregnant mother and her baby, including the brain and the gut, where they disrupt the microbiota.
The microbiota is the community of microbes in the gut. It helps produce short-chain fatty acids such as butyrate, which support immune function and brain development.
Researchers divided pregnant rats into groups. About half received methadone from mid-pregnancy through birth and early nursing, and some were also given sodium butyrate, either alone or alongside methadone.
The offspring were monitored from birth through adolescence and adulthood. Researchers found methadone exposure disrupted microbiota and the genetic codes needed to produce butyrate. Sodium butyrate reversed some of those disruptions.
In behavioural testing, methadone-exposed rats showed more signs of fear and stress. They also struggled in tasks measuring working memory, attention and impulse control.
Dr Isobel Williams, who led the experiments during her doctoral research at UNSW, said: “In people using opioids, the balance of gut bacteria is disrupted, and butyrate production drops. We wanted to see if replacing that missing butyrate could make a difference in rats because their biology closely mimics our own.”
The study also found methadone-exposed pups had reduced levels of myelin in brain tissue. Rats treated with sodium butyrate showed large improvements in myelin levels.
According to Clemens, growing evidence suggests opioid exposure in utero can lead to subtle but lasting developmental challenges, including difficulties with attention, anxiety, learning and impulse control.
She cautioned that more research is needed before human trials begin. However, she said the results raise the possibility of one day developing the first treatment to prevent or reverse harm from opioid exposure in children.
