Perinatal morphine exposure induces long-term changes in the intestinal microbiota of male and female rats.

The increased use of opioids by women of reproductive age has resulted in a dramatic rise in the number of infants exposed to opioids in utero. Although perinatal opioid exposure (POE) has been associated with an elevated risk of infection and hospitalization later in life, the mechanisms by which opioids influence immune development and maturation are not fully elucidated. Alterations in the intestinal microbiota composition, which lead to changes in immune training and maturation, could be at play. Chronic opioid use in adults is associated with a proinflammatory and pathogenic microbiota composition; therefore, we hypothesized here that in utero morphine exposure could negatively affect intestinal microbiota composition, leading to alterations in immune system function. We report that a clinically-relevant model of perinatal opioid exposure, in rats, induces profound intestinal microbiota dysbiosis that is maintained into adulthood. Furthermore, microbial maturity was reduced in morphine-exposed offspring. This suggests that the increased risk of infection observed in children exposed to opioids during gestation may be a consequence of microbiota alterations with a downstream impact on immune system development. Further investigation of how perinatal morphine induces dysbiosis will be critical to the development of early life interventions designed to ameliorate the increased risk of infection observed in these children.